M3: Ecosan Systems and Technology Components

M3: Ecosan Systems and Technology Components
DEMO-VERSION: LINKS TO EXTERNAL DOCUMENTS DO NOT WORK! M3: Ecosan Systems and Technology Components M 3-2: Ecosan Technologies to Close the Water Loop Source: P. Jenssen Prof. Dr. Petter Jenssen, Department of Mathematical Sciences and Technology, Norwegian University of Life Sciences Dr. Johannes Heeb, International Ecological Engineering Society & seecon international Dr. Ken Gnanakan, ACTS Bangalore, India Katharina Conradin, seecon gmbh © 2006 seecon International gmbh ACTS Agriculture -Crafts - Trades - Studies

Credits K. Conradin Materials included in this CD-ROM comprise materials from various organisations. The materials complied on this CD are freely available at the internet, following the open-source concept for capacity building and non-profit use, provided proper acknowledgement of the source is made. The publication of these materials on this CD-ROM does not alter any existing copyrights. Material published on this CD for the first time follows the same open-source concept for capacity building and non-profit use, with all rights remaining with the original authors / producing organisations. Therefore the user should please always give credit in citations to the original author, source and copyright holder. We thank all individuals and institutions that have provided information for this CD, especially the German Agency for Technical Cooperation GTZ, Ecosanres, Ecosan Norway, the International Water and Sanitation Centre IRC, the Stockholm Environment Institute SEI, the World Health Organisation WHO, the Hesperian Foundation, the Swedish International Development Cooperation Agency SIDA, the Department of Water and Sanitation in Developing Countries SANDEC of the Swiss Federal Institute of Aquatic Science and Technology, Sanitation by Communities SANIMAS, the Stockholm International Water Institute SIWI, the Water Supply & Sanitation Collaborative Council WSSCC, the World Water Assessment Programme of the UNESCO, the Tear Fund, Wateraid, and all others that have contributed in some way to this curriculum. We apologize in advance if references are missing or incorrect, and welcome feedback if errors are detected. We encourage all feedback on the composition and content of this curriculum. Please direct it either to or seecon K. Conradin

Credits ecosan Curriculum - Credits
K. Conradin ecosan Curriculum - Credits Concept and ecosan expertise: Johannes Heeb, Petter D. Jenssen, Ken Gnanakan Compiling of Information: Katharina Conradin Layout: Katharina Conradin Photo Credits: Mostly Johannes Heeb & Katharina Conradin, otherwise as per credit. Text Credits: As per source indication. Financial support: Swiss Development Cooperation (SDC) How to obtain the curriculum material Free download of PDF tutorials: Order full curriculum CD: € 50 (€ 10 Developing Countries) Release: 1.0, March 2006, 1000 copies Feedback: Feedback regarding improvements, errors, experience of use etc. is welcome. Please notify the above -addresses. Sources Copyright: Copyright of the individual sources lies with the authors or producing organizations. Copying is allowed as long as references are properly acknowledged. seecon

Contents Introduction
P. Jenssen Introduction Source Separated Wastewater Collection/Treatment Systems Greywater Volumes Characteristics Source Control Greywater Treatment Options Pretreatment Drip Irrigation Soil Infiltration Mound Systems Sand Filters Constructed Wetland Ponds Biofilters

Contents Greywater Treatment Options (cont.) Biofilters
P. Jenssen Greywater Treatment Options (cont.) Biofilters Conventional biological Treatment Chemical Treatment Membrane Filtration Reuse Complete System for one household Rainwater Harvesting Conclusion

Introduction This module will explain how the water loop can be closed. As in the module before, source separation is a prerequisite. Greywater makes up for the largest volume of the generated “wastewater”, but contains the lowest share of nutrients and pathogens. Energy Water (drinking water) Nutrient Filtration (membrane, sand) Fertilizer (N, P, K) Grey-water Black-water Ground-water recharge This module will explain how the water loop can be closed. As in the module before, source separation is a prerequisite. Greywater makes up for the largest volume of the generated “wastewater”, but contains the lowest share of nutrients and pathogens. Soil amend-ment Organic waste Biologi-cal Treat-ment Recrea-tional water Aerobic treat-ment (composting) Anaerobic treat-ment (biogas) Watering garden

Source Separated Wastewater Collection/Treatment Systems
P. Jenssen As has been shown in the previous module, Ecosan technologies are based on source separating techniques. While the last module has dealt with the collection and treatment/hygienization of black and yellowwater, this module will focus on greywater. Greywater, as the term is used here, includes water from sinks, showers, washing machines, dishwashers, but excludes all water polluted with human excreta (toilets, urinals). Greywater is only slightly polluted wastewaters from dishwashing, showers, laundry machines, water from sinks etc. Greywater makes up for the largest share of wastewater. Yellow water is either urine diluted with flushwater or pure urine. Urine contains most of the nutrients we excrete again, but only has a very low, if at all, pathogen count. However, we also excrete micro-pollutants or endocrine substances through urine. Brownwater refers to faeces mixed with (flushing) water, but no urine. Most of the pathogens and a high proportion but rather little of the nutrients are contained here. Blackwater is urine and faeces mixed with or without domestic wastewater from showers, washing machines, sinks etc.

Greywater Volumes Greywater amounts per person can vary greatly.
Here: range from l/person/day Norway USA Ecovillage Kaja (Norway) Blackwater 40 57 7 Greywater 120 133 81 112 Total 160 180 117 Source: Jenssen (8) Source: (8) The amount of greywater produced in a household can vary greatly. While the water consumption in poor areas is about litres per person per day, a person in a richer area may generate several hundreds of litres a day (3). The table shows that the per capita greywater production varies from 81 to 133 liters. The lowest greywater production displayed is from a Norwegian ecovillage project and shows what is possible to achieve if the people are focused on water conservation. Vinnerås (2) reports that in a Swedish Ecohousing development the greywater production is only 66 liter per person and day. At the student dormitories (Kaja) at the University in Ås, Norway, the greywater production is higher despite water saving showerheads. Without water saving showerheads the greywater production was 156 liters per student per day. This shows that the showers account for a major part of the greywater production in the student dormitories. In Norway young people (15 – 25 years) generally take more frequent and longer showers than the rest of the population and thus it can be expected that the average greywater production for the population as a whole is lower than at Kaja. In the proposed new Swedish guidelines a greywater production of 100 liters/person and day is suggested (2).

Greywater Characteristics
Source: Vinnerås (2) NUTRIENT CONTENTS OF GREYWATER In a recycling system based on source separation of wastewater fractions, water saving or dry toilets are used, hence, the greywater volume constitutes >90% of the total wastewater flow. The toilet waste contains the majority of the nutrients and only 10% of the nitrogen, 26% of the phosphorus and 21% of the potassium is found in the greywater (2). In Norway where phosphate free detergents are used the phosphorus content in greywater is less than 20%. Nutrient removal then becomes a minor issue. Greywater volumes can constitutes >90% Limited amount of nutrients in greywater, depending on use. Phosphate content: depending on whether detergents contain phosphate or not Source: (9)

K. Conradin NUTRIENTS IN GREYWATER normally low levels of nutrients high concentrations of phosphorous possible (washing and dish-washing detergents) P-free detergents available detergents containing phosphorous banned in some countries for water protection SUSPENDED SOLIDS AND BIODEGRADABLE ORGANIC COMPOUNDS Composition of greywater varies greatly  reflects lifestyle of residents Greywater often contains high concentrations of easily degradable organic material (fat, oil and other organic substances from cooking, Separate collection of cooking oil for conversion to biodiesel Cooking oil can be added directly to anaerobic digesters  biogas. NUTRIENTS IN GREYWATER Greywater normally contains low levels of nutrients compared with normal wastewater containing toilet waste. Levels of nitrogen and other plant nutrients are always low, but in some greywater high concentrations of phosphorous can be found. This phosphorous originates from washing and dish-washing detergents. Washing and dish-washing detergents without phosphorous are available on the market. If people use only P-free detergents, the phosphorus concentration of the greywater become very low and often below 1mg/l without treatment. Some progressive countries (e.g. Norway) and some cities in East Asia have banned detergents containing phosphorous for water protection. SUSPENDED SOLIDS AND BIODEGRADABLE ORGANIC COMPOUNDS The composition of greywater varies greatly and reflects the lifestyle of the residents and the choice of household chemicals for washing-up, laundry etc. Characteristic of greywater is that it often contains high concentrations of easily degradable organic material, i.e. fat, oil and other organic substances from cooking, residues from soap and tensides from detergents. In countries where there is extensive use of cooking oil this must be accounted for when designing the greywater treatment system. Separate collection of cooking oil for conversion to biodiesel (30) is one interesting alternative. Used cooking oil can also added directly to anaerobic digesters for conversion to biogas. Greywater Treatment in Luebeck, Germany

PATHOGENS Generally low proportion of pathogens Faecal contamination: showering, washing of clothes and diapers Indicator bacteria such as faecal coliforms may multiply in the septic tank  overestimation of risk possible Source: Ridderstople (3) The proportion of pathogens in greywater is generally low. Pathogens are primarily added to wastewater with the faeces. Faecal contamination of the greywater may occur from showering, washing of clothes and diapers. Indicator bacteria as faecal coliforms can multiply in the septic tank of greywater treatment systems and may, thus, overestimate the faecal contamination (21). The risk of infection is a function of the faecal contamination of the water (4) and the treatment required to achieve acceptable risk is dependent on the final use or disposal of the greywater (34). Viruses may pose a higher risk than bacteria in greywater (21). Since normal faecal load in mixed wastewater from households is about 150 grams per person per day, treated greywater which does not contain faeces, poses only a fraction of the risk of normal wastewater. A well-functioning wastewater treatment plant including mechanical, chemical and biological steps can be expected to remove more than 90–99,9% of incoming pathogens. Treated greywater can, thus, be expected to have a better hygiene quality than any kind of mixed wastewater Mixed wastewater, untreated Mixed wastewater, treated in advanced WWTP Greywater, untreated Greywater, treated in vertical soil filter bed Levels of potential pathogens in different waters. Levels of pathogens in the untreated waters are based on measured faecal load to greywater in Vibyåsen, Sweden, compared to the faecal contamination in normal mixed wastewater.

K. Conradin METALS AND OTHER TOXIC POLLUTANTS content of metals and organic pollutants in greywater is generally low  increase by addition of hazardous substances Levels of metals: approximately same as in mixed wastewater from a household, Origin: water itself, corrosion of the pipe system and from dust, cutlery, dyes and shampoos etc. Organic Pollutants: Most organic pollutants in the wastewater are found in the greywater fraction: similar level as mixed wastewater Origin: household chemicals, shampoos, perfumes, preservatives, dyes and cleaners Content of metals and organic pollutants in greywater is heavily affected by human behaviour! METALS AND OTHER TOXIC POLLUTANTS The content of metals and organic pollutants in greywater is generally low, but can increase due to addition of environmentally hazardous substances. The levels of metals in greywater are for most substances approximately the same as in a mixed wastewater from a household, whereas for zinc and mercury the levels are lower (6). Metals in greywater originate from the water itself, from corrosion of the pipe system and from dust, cutlery, dyes and shampoos etc. used in the household. Most organic pollutants in the wastewater are found in the greywater fraction, hence the levels are in the same concentration range as in a mixed household wastewater. Organic pollutants are present in many of our ordinary household chemicals, e.g. shampoos, perfumes, preservatives, dyes and cleaners (7). They can also be found in furnishing fabrics, glue, detergents and floor coatings. The content of metals and organic pollutants in greywater is heavily affected by human behaviour. By using environmentally-friendly household chemicals, and not pouring hazardous substances such as paint, solvents etc. into the washbasin, the levels of metals and organic pollutants in greywater can be kept low. Source: (3)

Greywater: Source Control
Managing greywater: attention to the composition of soaps, cleansers and other household chemicals. Main criteria for sizing of greywater system: Hydraulic load load of easily degradable organic matters and BOD Reducing these parameters gives more cost efficient and volume- and area-saving solutions. Source control includes: water-saving equipment (taps, showerheads) BOD load: controlled use ofdetergents, shampoos, soaps, controlled disposal of grease / oil. Removing of all larger particles: Use filtes and screens Any strategy for managing greywater will be made easier by water conservation measures as well as attention to the composition of soaps, cleansers and other household chemicals. […] Hydraulic load and the load of easily degradable organic matters and BOD (biochemical oxygen demand), are the main criteria used for sizing a greywater system. Technical components such as septic tanks, sand filters, soil infiltration systems or other treatment applications are mainly sized based on hydraulic load and BOD. Reducing these parameters at the point of origin gives more cost efficient and volume- and area-saving solutions. Source control measures, as mentioned below, reduces maintenance cost and improves purification. Source control includes: The use of water-saving equipment (taps, showerheads) BOD load: No overdosing of detergents, controlled use of shampoos and soaps etc., controlled disposal of grease and oil used in food preparation. Removing of all larger particles, fibres and grease to prevent clogging of the pipe system (screens & filters). Installation of special grease traps in restaurants may be necessary. High levels of organic matter, phosphorus, toxic organic substances and heavy metals originate largely from detergents and household chemicals. Information regarding household chemicals is necessary, as well as an adaptation of users (i.e. use of phosphate-free detergents). Drawing: Per Hardestam, Karlstad Reklam AB (Source: 3) Source: (3) Biochemical oxygen demand (BOD) is a measure of how much dissolved oxygen is being consumed as microbes break down organic matter. A high demand, therefore, can indicate that levels of dissolved oxygen are falling, with potentially dangerous implications for the river’s biodiversity. High biochemical oxygen demand can be caused by: high levels of organic pollution, caused usually by poorly treated wastewater high nitrate levels, which trigger high plant growth Both result in higher amounts of organic matter in the river. When this matter decays, the microbiological activity uses up the oxygen. Biochemical oxygen demand is therefore one of the main parameters used in the Urban Wastewater Treatment Directive for controlling discharges. Unsurprisingly, large rivers – where wastewater plants are more likely to be located – register higher levels of oxygen demand than smaller rivers. Improvements in wastewater management causes biochemical oxygen demand to fall in all sizes of rivers (10).

Greywater Treatment Options
Here: Focus on natural systems: soil infiltration, constructed wetlands, ponds: small energy cost no chemicals require larger areas than the conventional systems Source: (9) P. Jenssen K. Conradin Natural systems as soil infiltration, constructed wetlands and ponds have small energy cost and do not use chemicals. These systems can be integrated as part of a treatment park or natural environment. When recycling of nutrients is not the main issue, as it is with treatment of greywater, natural systems are intuitively sustainable. However, most natural systems require larger areas than the conventional/more technical systems. In an urban setting area may be a limiting factor. Below some aspects of various treatment systems for greywater are briefly discussed. The natural systems are given most attention. The cost and sustainability aspects of the different systems are not considered because good data for making such comparisons regarding greywater treatment are lacking. Activated Sludge Treatment Constructed Wetlands

P. Jenssen

lower hygienic risk a environmental problem than mixed wastewater large amounts of easily degradable organic matter Anaerobic conditions  smell  primary target: remove organic compounds secondary treatment target reduce levels of pathogens reduce levels of organic pollutants and heavy metals.  important if used for irrigation Greywater compared with mixed wastewater poses a much lower hygienic risk and a environmental problem. Greywater contains relatively large amounts of easily degradable organic matter. If anaerobic conditions occur, greywater can be a strong source of smell. A primary target is therefore to remove the organic compounds (measured as BOD) that are responsible for odour nuisance. A secondary treatment target, may be to reduce the levels of pathogens and other micro- organisms in the water. This is especially important when people may be directly exposed to the greywater. A further ambition for treatment and post-treatment (secondary treatment, see below) can be to reduce levels of organic pollutants and heavy metals. This can be important when greywater is used for groundwater recharge and for irrigation.

Pretreatment P. Jenssen

Pretreatment  to avoid clogging of the subsequent treatment system
solid-liquid separation by gravity, flotation, screens septic tanks (most common), settling tanks, ponds, filter systems such as filter bags. Small systems: direct use of greywater possible (e.g. mulch bed) Pretreatment is needed in order to avoid clogging of the subsequent treatment system. The pre-treatment consists of a solid-liquid separation that reduce the amounts of particles and fat in the effluent by gravity, flotation, screens, or filters. Technologies for solid-liquid separation include septic tanks, settling tanks and ponds and filter systems such as filter bags. The most common pre-treatment unit for greywater as well as for treatment of combined wastewater (greywater and excreta) onsite is a septic tank (see below) For small systems, as a single dwelling, alternatives to the septic tank can be used. Filterbags from natural or synthetic material can produce the same effluent quality as a septic tank (27). The bags can be removed by the homeowner and there is no need for vacuum trucks. However, proper caution needs to be taken in order to avoid pathogen risk when removing the bags. The natural fiber bags can be composted together with their content. It is also a possibility to dry the bags with their content and reuse the bag if synthetic fabrics are used. Practical experience has shown that home made screens or filters constructed of fine gravel straw or branches may be appropriate prior to soil infiltration in small scale domestic systems in warm climate. In small systems direct use of greywater is also possible i. e. to a mulch bed where water is used for growing plants or trees. There is no scientific evidence giving specific design criteria for simple filter systems or mulch beds. There are many different designs of septic tanks. Newer septic tanks often come with an effluent filter. The filter can reduce BOD and suspended solids significantly. Source: Adapted from (29)

Drip irrigation P. Jenssen Note: While primary treatment mainly reduces solids and parts of the organic compounds (BOD) in the wastewater, secondary treatment is necessary to further decrease the BOD as well as to remove pollutants and pathogens from the remaining liquid.

Drip Irrigation long, flexible tubing with engineered openings or emitters. to drip at slow rate into the surrounding soil vegetation can also adsorb the nutrients Vegetation helps to clean greywater efficient use of water. Emitter or dripper Wetted root zone Source: FAO Source: Adapted from (29) Drip Irrigation is a method of dispersal and disposal which uses long, flexible tubing with engineered openings or emitters. The systems require vegetative cover. These emitters allow the pumped wastewater to drip at slow rate into the surrounding soil. By releasing the effluent slowly into soil, the vegetation can also adsorb the nutrients and help to treat the wastewater/greywater. If the vegetation does not absorb all the water percolation down to the groundwater may occur. In order to avoid clogging of the emitters, a filtration unit after the septic tank is recommended. Drip irrigation can be a great aid to the efficient use of water. A well designed drip irrigation system will lose practically no water to runoff, deep percolation or evaporation. Irrigation can be precisely managed to meet individual crop demands; thus higher crop yields can possibly be reached. Advanced drip irrigation systems with pressurized distribution of the liquid are available. Such systems are capital intensive and are suited for watering the green areas of hotels golf courses etc, but can also be used by professional growers if the proper hygiene considerations are taken. Drip irrigation systems should be installed according to the manufacturers specifications.

Soil Infiltration P. Jenssen

Soil Infiltration After leaving the septic tank/pre-treatment unit the effluent is distributed to the soil through open ponds or shallow trenches or infiltration basin. Efficient way of treatment P. Jenssen Soil infiltration is a simple and suitable method for greywater treatment. Comprehensive experience exists regarding soil infiltration of combined wastewater and in the U.S., soil infiltration is the primary system for onsite and decentralized wastewater treatment. Soil infiltration systems have the potential to achieve high treatment efficiencies over a long service life at low cost, and be protective of public health and environmental quality (11,12). After leaving the septic tank/pre-treatment unit the effluent is distributed to the soil through open ponds or shallow trenches or infiltration basin. Infiltration in open basins/ponds (above) and in buried shallow trenches (below) the percolation down to the groundwater and subsequent flow towards a stream is indicated.

Soil Infiltration P. Jenssen water percolates down through an unsaturated zone to the groundwater (saturated zone). Most of the treatment: unsaturated zone Size according to local soil conditions! Careful design necessary: systems may endanger groundwater quality. Suitable sites: deep, well-drained, well-developed, medium-textured soils Impermeable soils, shallow rock, shallow water tables, or very permeable soils such as coarse sand or gravely soils are considered unsuitable sites  special design necessary The water percolates down through an unsaturated zone to the groundwater (saturated zone). Most of the treatment occurs in the unsaturated zone where water flows in the smaller pores and air is present in the larger. It is important to size and load the system according the local soil conditions to keep the flow unsaturated because this provides optimum conditions for filtering and sorption of pathogens and other pollutants. Unsaturated flow also assures aerobic conditions that generally promote more rapid die-off of pathogens than anaerobic conditions. When using soil infiltration systems particular care has to be taken because the groundwater is receiving the treated effluent and there are sites where infiltration systems may endanger groundwater quality. Suitable sites for infiltration have deep, well-drained, well-developed, medium-textured soils (such as medium to fine sand and silty sands and sandy loam). After one meter of vertical percolation during unsaturated conditions more than 3 logs of bacteria removal can be expected in a well functioning system (12). Virus and bacteria removal, as well as phosphorus sorption is enhanced by soils rich in iron and aluminum oxides (brown and red color soils). Impermeable soils, shallow rock, shallow water tables, or very permeable soils such as coarse sand or gravely soils are considered unsuitable sites, but may be suitable if special system design is used. For permeable soils a layer of sand cm in the bottom of the infiltration trench may be sufficient to allow infiltration in such soils. Elevated systems (mounds) can also be designed to overcome limitation in the local soil conditions (USEPA 2001). Trench for Soil Infiltration Source: Adapted from (29)

Mound Systems P. Jenssen

Mound Systems Similar to soil infiltration
P. Jenssen Sand Distribution Layer Water level monitoring pipes Mound System under construction P. Jenssen Similar to soil infiltration technique when existing soil is unsuitable for greywater disposal layer of soil on top of which the sand mound is built, is still biologically and chemically active  helps in treatment Mound systems work similarly to soil infiltration. An elevated absorption field is used for the infiltration of greywater. For irrigation, a layer of sand fill and top soil is placed over existing soil. This technique is usually done when existing soil is unsuitable for greywater disposal or where the hydraulic conductivity is low. Pipes are usually placed near the root zone to provide irrigation. The layer of soil on top of which the sand mound is built, is still biologically and chemically active, and thus helps to treat the applied greywater. The sand provides a surface for bacteria to grow on and treat greywater, as well as being a physical filter for solids. The sand is not saturated with water, so that aerobic treatment can take place (adapted from: 13). The size of the infiltration surface is to be determined based on classification of the sand, and the geometry of the sand layer is determined by the hydraulic properties of the underlying soil (28).

Sand Filters P. Jenssen

Sand Filters Water level monitoring pipes Distribution Layer Sand Geotextile/insulation Bottom drainage P. Jenssen well known method for wastewater and greywater purification planted sandfilter: often termed vertical flow wetlands, Vertical water flow Plants: help to avoid clogging, otherwise not much difference between planted and unplanted systems. The sand filter is a well known method for wastewater and greywater purification and has been in use for more than 100 years (14). Over the last two decades planted sand filters have become more common. The planted sandfilter is often termed vertical flow wetlands, since wetland plants are grown in the sandfilter. The water flow is vertical and unsaturated and the treatment processes equal to the unsaturated zone in a soil infiltration system. The plants may have a positive effect on breaking up the biological clogging layer on the filter surface, but apart form that there is not much difference in the system performance between planted and unplanted systems. The purification performance is as for soil infiltration systems dependent on the hydraulic loading and the sand texture and surface chemistry of the sand grains. Typical loading of sand filters are in the range of 2 – 10 cm/d. Finer and medium sands should not be loaded at higher rates than 5 cm/d. In fine and medium sands more than 3 log reduction of indicator bacteria can be expected. The BOD removal is typically > 80% and the effluent usually has suspended solids (SS) < 5mg/l (12). Bacteria, virus and phosphorus removal is enhanced when using sand rich in iron oxides. In order to improve aeration and to avoid short-circuiting through the backfill around the sandfilter it is recommended to construct the filter with sloping sand walls on the sides of the gravel or distribution layer.

Constructed Wetland P. Jenssen P. Jenssen

Constructed Wetland Constructed wetlands: Artificial shallow ponds vegetated with macrophytes Often: subsurface flow constructed wetlands Porous media: sand, gravel, light weight aggregate, crushed brick etc. Fine grained soils: not suited (low hydraulic conductivity) K. Conradin Artificial shallow ponds vegetated with macrophytes are normally termed constructed wetlands. If the pond is filled with a porous media it is termed a subsurface flow constructed wetland; here subsurface flow constructed wetlands are described. The porous media can be sand, gravel, light weight aggregate, crushed brick or other media suited to support the macrophytes and at the same time have a sufficient hydraulic conductivity to transport water horizontally through the root zone. Fine grained soils as silt or clays are not suited in subsurface flow constructed wetlands due to low hydraulic conductivity (capacity to transport water) and consequently a high risk for surfacing of flow and short-circuiting of the system resulting in poor treatment performance (9). Subsurface Flow Constructed Wetland for greywater treatment. Ecological Settlement, Luebeck Flintenbreite, Germany

Constructed Wetland  Geometry: based on hydraulic calculations
Cold climate: pre-treatment is recommended deeper systems Warmer climate: 0.4 – 0.6 m deep systems common The geometry of subsurface flow constructed wetlands is based on hydraulic calculations (32). Media with a high hydraulic conductivity normally yield systems where the width is shorter than the length in the flow direction. If the conductivity is low the width may exceed the length of the system. In cold climate where the plants are dormant aerobic pre-treatment is recommended (16) to achieve high removal of BOD and nitrogen in the cold season. In cold climate deeper systems are used because this allows for the upper part to freeze while the water still can flow lower down. In cold temperate climate 1 m deep systems are recommended. In warmer climate 0.4 – 0.6 m deep systems are the most common (9). P. Jenssen P. Jenssen Constructed Wetland in Ås, Norway, in the summer and in the winter, an area of 2 m2 per Student is needed (Total 48 Students)

Constructed Wetland Constructed wetlands:
generally good reduction of BOD and total nitrogen Phosphorus removal: dependent on the phosphorus sorption capacity of the porous media good pathogen removal In warm climates: possible without pretreatment biofilter. Constructed wetlands generally perform well with respect to reduction of BOD and total nitrogen. Phosphorus removal is dependent on the phosphorus sorption capacity of the porous media (17, 31). Constructed wetlands have a large potential for pathogen reduction and in Norway systems for receiving greywater and combined wastewater generally produce an effluent with < 1000 thermotolerant coliforms/100ml (16,18). Normally the pathogen reduction of constructed wetlands depends on the size of the porous media and the retention time. A specially developed lightweight aggregate for use in constructed wetlands that has very high phosphorus sorption capacity as well as ability to remove of indicator bacteria and somatic coliphages (33). There are also indications that the macrophytes may enhance bacteria removal (19). In warm climates and if the area is not restricted a greywater treatment wetland can be constructed without a pretreatment biofilter. Without the biofilter the dosing system (pump/siphon) can also be omitted. However, with a biofilter more compact systems can be made (18). This is needed in urban applications.  Refer to the Tutorial Module for the latest version of this slide P. Jenssen A subsurface flow wetland with and without integrated biofilter (14)

Ponds P. Jenssen P. Jenssen

Ponds Ponds: developed for combined wastewater
also well suited for greywater treatment shallow man-made basins  wastewater flows  retention time of several days effluent is discharged low in BOD Nitrogen reduction; 70-90% Phosphorus removal 30-45% Very robust design Limiting factors: size P. Jenssen Ponds, or wastewater stabilization ponds (WSP) are developed for combined wastewater, but are also well suited for greywater treatment (Ottoson 2003). Wastewater stabilization ponds are shallow man-made basins into which wastewater flows and from which, after a retention time of several days, rather than hours in conventional treatment processes, the effluent is discharged low in BOD and also with a substantial bacteria reduction (20). WSP systems may consist of a series of ponds – anaerobic, facultative and several maturation ponds, whereas for greywater treatment, an anaerobic stage usually is not required. Modern WSP design procedures are able to achieve BOD removals of >90%. Total nitrogen removal is 70-90%, and total phosphorus removal 30-45%. WSPs are particularly efficient in removing excreted pathogens. A properly designed series of WSP can easily reduce faecal coliform numbers from 108 per 100 ml to <103 per 100 ml. WSP are also extremely robust: due to their long hydraulic retention time, they are more resilient to both organic and hydraulic shock loads than other wastewater treatment processes (20). Ottosen (21) refers to an investigation by Gunther (2000) where a pond system in Sweden with a retention time of one year reduced E.coli and somatic coliphages by 1.2 and 3 logs respectively. However, the size required by 1 year retention time as well as potential direct contact with contaminated water will limit the use of ponds as the main treatment component for greywater systems in urban areas. As a polishing step of effluent from biofilters, sandfilters or constructed wetlands ponds may have a function in an urban environment both as a purification step and a landscape element (9).  Refer to the Tutorial Module for the latest version of this slide Source: Adapted from (29)

Biofilters P. Jenssen P. Jenssen

2m Biofilters 0,6m Biofilter:
covered by a compartment which facilitates spraying of the greywater (septic tank effluent) over the biofilter surface. standard depth of 60 cm grain size within the range 2 – 10 mm Filling material: light weight aggregate, gravel etc. biofilm develops: reduction of BOD and pathogens. Clogging: has not been observed uniform distribution of the liquid is important Biofilters consist of a biofilm support media onto which the wastewater is is charged. The biofilm support media may consist of different materials natural and man made. Examples are gravel, crushed rock, crushed, brick, lightweight aggregates of clay or plastic or different kind of plastic mesh material. Natural material as crushed coconut shell has also been suggested. The key is to have a rigid material that can support biofilm growth and that has a high surface area per unit volume of media. The biofilm is a thin slime layer that quickly establishes on the available surface area of the support medium upon exposure to wastewater. The biofilm efficiently degrades organic matter (BOD) and also help to reduce microorganisms in the wastewater. The picture shows a biofilter for cold climate developed in Norway (16, 18) . The biofilter is covered by a compartment (e.g. a hemispherical dome) which facilitates spraying of the STE (Septic Tank Effluent) over the biofilter surface. The biofilter has a standard depth of 60 cm and a grain size within the range 2 – 10 mm is recommended. In Norway light weight aggregate (LWA) in the range 2 – 4 mm is the most common filter media, but gravel or other type media in the above size range may be used. Using such biofilters for treating greywater, more than 70% BOD reduction and 2-5 log reduction of indicator bacteria has been obtained at a loading rate for greywater up to 115 cm/d. Suspended Solids are reduced by 60-80%. Assuming a greywater production of 100 litres/person/day a biofilter of 1 m2 surface area can treat greywater from about 10 persons; thus, very compact biofilters can be made (9). 2m 0,6m LWA Diameter 2,5 mm Surface area > 5000m2/m3 Jets

Biofilters Pretreatment biofilter Pump/siphon Septic tank
A biofilter alone may be sufficient for treatment of greywater. In Norway several small compact greywater biofilters are commercially available for use in cottages or single dwellings. In order to further improve the quality of the effluent, the biofilter can be followed by a subsequent sandfilter (see above) or a constructed wetland (see above). This is needed if the receiving water body is sensitive (9).  Refer to the Tutorial Module for the latest version of this slide Level control & sampling port Horizontal subsurface flow wetland filter

Conventional Biological Treatment
P. Jenssen

(enhanced) active sludge treatment fixed film systems: trickling filters or rotating biological contactors Advantage: compact setting (i.e. in densely populated urban settings) Efficient reduction of organic matter Bacteria and virus requirement: succeeded other methods such as sand filter, subsurface flow constructed wetland Chemical treatment also possible Active Sludge Treatment aeration concrete: greywater mixed with recycled sludge containing active aerobic bacteria Sludge decanting in attached tank --> returned to the aeration tank. Pretreatment necessary Assumption: low treatment efficiency due to low nutrient content, but probably good for heavily loaded greywater Conventional biological treatment, means active sludge or enhanced active sludge systems and fixed film systems as trickling filters or rotating biological contactors (RBC). A RBC especially designed for greywater treatment was available in Germany (23). The advantage of these systems is that they are compact (i.e. in densely populated urban settings) and that they efficiently reduce organic matter. In order to meet the bacteria and virus requirements suggested by Ottoson (21) these biological methods must be succeeded by other methods as a sand filter, subsurface flow constructed wetland with a fine grained substrate or disinfection. Combination with chemical treatment will also be possible. Activeted Sludge Treatment An activated sludge treatment unit usually consists of an aeration tank, in which the wastewater is mixed with recycled sludge containing active aerobic bacteria. The mixed liquid is aerated and the organic pollutants are degraded (partly oxidized and partly integrated into new biomass). In an attached tank, sludge is decanted and returned to the aeration tank. A pretreatment (mainly in the case of heavily loaded wastewater) and a complex process chain for sludge treatment is necessary (24). Activated sludge systems have not been extensively investigated for greywater treatment. Gunther (2000) assumed that the treatment efficiency for greywater will be low due to the low content of nutrients and readily biodegradable matter. P. Jenssen

RBC – Rotating Biological Contactors Series of closely spaced circular discs high surface area for the growth of micro-organisms discs submerged about 50% and rotate slowly aerobic biological film alternatively exposed to air or wastewater Dead biofilm drops  sludge. Source: Adapted from (29) sludge outlet submerging biomass outlet rotating disc inlet post treatment Source: (24) RBC – Rotating Biological Contactors Rotating contactors are constructed from a series of closely spaced circular discs which provide a high surface area for the growth of micro-organisms. The discs are submerged about 50% and rotate slowly in a tank which contains the greywater to be treated. The discs are covered with an aerobic biofilm which is alternatively exposed to air, taking up oxygen, and submerged to the wastewater, taking up nutrients. Dead bio-film is dropped off automatically from the discs into the wastewater stream. The common disc diameter is between 0,6and 3 m (24). In Germany a successful system using rotating biological contactors have been developed. The system is compact and can be located for instance in the basement of an apartment building. In order to achieve reduction of fecal indicators of more than 3 logs the system is equipped with UV-disinfection.  Refer to the Tutorial Module for the latest version of this slide Source:

Trickling Filter concrete column filled with a coarse carrier material (crushed rock, slag, gravel or plastic modules) conventionally 1 to 3 m deep. Even distribution of wastewater  bio-film develops micro-organisms of the bio-film degrade wastewater pollutants Aeration from the bottom inlet Trickling filter Pre-treatment outlet Trickling Filter A trickling filter is made of a concrete column filled with a coarse carrier material of crushed rock, slag, gravel or plastic modules. Conventionally, the bed is 1 to 3 m deep. Wastewater is distributed evenly on the filter surface and percolates downwards into the filter bed. On the highly permeable bed a bio-film develops. The micro-organisms of the bio-film degrade wastewater pollutants. Aeration of the filter media takes place from the bottom through a spontaneous air flow due to temperature difference. Therefore, sub-soil construction is not common. Usually, the organic and the hydraulic load to the filters should guarantee a balance between the growth of the bio-film and the amount of rinsed-out dead bio-film. Constant hydraulic loading can be maintained through suction level controlled pumps or dosing siphons (24).  Refer to the Tutorial Module for the latest version of this slide Source: (24)

Chemical Treatment P. Jenssen P. Jenssen

Chemical Treatment Chemical treatment
primarily used to reduce phosphorus, but also organic matter chemical precipitation also reduces virus and bacteria. Compact systems (suitable for urban areas) post treatment in a sandfilter or wetland

Membrane Filtration P. Jenssen P. Jenssen

Membrane Filtration semi-permeable membrane + osmotic or lower pressure dissolved solids or other constituents captured as the retenate semi-permeable membrane + osmotic or lower pressure dissolved solids or other constituents captured as the retenate Retaining of different particle sizes: Microfiltration Ultrafiltration nanofiltration reverse osmosis Use in greywater treatment: tertiary removal of dissolved salts, organic compounds, phosphorus, colloidal and suspended solids, and human pathogens, including bacteria, protozoan cysts, and viruses Source: (26) Membrane processes use a semi-permeable membrane and osmotic or lower pressure differential to force water through the membrane as permeate, with dissolved solids or other constituents captured as retained. Membranes are often made of organic polymers, but new types of inorganic polymers as well as ceramic and metallic membranes are under development. The basic membrane systems include microfiltration, ultrafiltration, nanofiltration and reverse osmosis (RO), each of which retains a different range of particle sizes (29). For wastewater or greywater treatment applications, membranes are currently being used for the tertiary removal of dissolved salts, organic compounds, phosphorus, colloidal and suspended solids, and human pathogens, including bacteria, protozoan cysts, and viruses (26). The biggest single technical challenge with the use of membranes for wastewater treatment is the fouling that occurs. Membrane fouling appears to be mainly due to colloids, soluble organic compounds, and bacteria that are present in secondary effluent and are typically not well removed with conventional pretreatment methods. Membrane fouling results in an increase in feed pressure and requires frequent cleaning of membranes. This leads to a reduction in overall facility efficiency and a shorter membrane life (26). Treating greywater with membranes is a viable (but costly) option when considering urban reuse, agricultural reuse, industrial reuse, groundwater recharge, salinity barriers, and augmentation of potable water supplies, or to meet very low effluent water quality limits for nutrients. Membrane filtration offers excellent removal of microorganisms and organic matter and is therefore particularly interesting for upgrading of treated greywater to meet requirements for in-house use (9).  Refer to the Tutorial Module for the latest version of this slide

Membrane Filtration P. Jenssen P. Jenssen

Reuse Reuse of all greywater makes water savings exceeing 90% possible when a water efficient toilet is used (1). P. Jenssen Local discharge into water bodies: where sufficient water is available If high quality effluent is reached Use in Irrigation: closes the water cycle Local in garden or big scale P. Jenssen Reuse of treated greywater is highly advisable. Depending on the quality of the effluent, and depending on general water availability and use, different options are possible. Reuse of all greywater makes water savings exceeding 90 percent possible when a water efficient toilet is used (1). A brief overview of some of the various options is given here. Note that specific guidelines are not presented here. For this, readers are referred to the WHO Guidelines on the Reuse of Greywater and excreta, which will be published in the beginning of 2006 ( Local discharge into water bodies: This option is often chosen in countries where sufficient water is available, and if small volumes are treated. As most options presented here reach a very high quality of the effluent concerning BOD and nutrient content, as well as Suspended Solids and pathogens, it is a valid option where water is present in abundance (i.e. sufficient rainfall etc.) Use in Irrigation: The reuse of treated greywater in irrigation is very sensible, as it closes the water cycle. Moreover, less water has to be taken from rivers and other aquatic ecosystems, thus leaving them intact. Note that if treated greywater is used for the irrigation of food crops, a high effluent quality concerning pathogens has to be guaranteed. Irrigation can either take place locally, i.e. in private gardens, or, as shown, on a large scale for agricultural irrigation.  Refer to the Tutorial Module for the latest version of this slide

Reuse Inhouse Use: Inhouse uses:
especially where no drinking water quality is required, (toilet flushing, clothes washing, or showering) Reduces consumption of drinking water Drinking water quality possible with reversed osmosis P. Jenssen (c) Siegrist et al (11) Groundwater Recharge Where groundwater table has been lowered Inhouse Use: Treated greywater can be used for inhouse uses as well, especially where no drinking water quality is required, e.g. for toilet flushing, clothes washing, or showering. Thus the consumption of treated freshwater with drinking water quality can be reduced, thereby also lowering treatment and energy costs for drinking water. To upgrade to drinking water quality or for washing, micro filtration, reverse osmosis or carbon filtration may be needed as a single step or in combination along with ultraviolet light or similar disinfection process. Groundwater Recharge Especially in areas where the main freshwater source is groundwater, or where the groundwater table has been lowered, it makes sense to use treated greywater to recharge the groundwater. However, this can also be done without the above mentioned reasons, if water supply is abundant. Care has to be taken that the effluent quality is high, so that no pollution of the groundwater takes place.  Refer to the Tutorial Module for the latest version of this slide

Complete System for One Household
Biofilter Blackwater holding tank Pump chamber Septic tank Using a blackwater holding tank (for urine and faeces), a septic tank and a biofilter, wastewater of a single household can be adequately dealt with without an extensive sewer system. This is particularly interesting for remote areas with scattered buildings, where a sewer system would be extremely expensive. Blackwater can be pumped out of the holding tanks by vacuum truck and brought to a treatment plant (i.e. biogas plant, liquid composting etc.)  Refer to the Tutorial Module for the latest version of this slide

Conclusion Pilot project Hui Sing Garden Greywater treatment (Malaysia) 1st chamber of oil and grease trap Pump sump Final discharge P. Jenssen Three water samples from the Hui Sing Garden Greywater Treatment, working with a constructed wetland. The picture visualises the treatment efficiency.

END OF MODULE M3-2 seecon ACTS
Source: P. Jenssen END OF MODULE M3-2 Prof. Dr. Petter Jenssen, Department of Mathematical Sciences and Technology, Norwegian University of Life Sciences Dr. Johannes Heeb, International Ecological Engineering Society & seecon international Dr. Ken Gnanakan, ACTS Bangalore, India Katharina Conradin, seecon gmbh © 2006 Click here to go to the further information part BACK TO THE MAIN MENU seecon International gmbh ACTS Agriculture -Crafts - Trades - Studies

++ References Alsén, K.W. & Jenssen, P. D. (2005): Ecological Sanitation – for mankind and nature. Norwegian University of Life Sciences, As, Norway Vinnerås, B. (2002): Possibilities for sustainable nutrient recycling by faecal separation combined with urine diversion. Agraria Doctoral thesis. Swedish University of Agricultural Sciences, Uppsala. - In: Jenssen, P.D., Greatorex, J.M, & Warner, W. S. (2004): Sustainable Wastewater Management in Urban Areas. = Kapitel 4. Kurs WH33, Konzeption Dezentralisierter Abwasserreinigung und Stoffstrommanagement. Universität Hannover. Ridderstolpe, P. (2004): Introduction to Greywater Management. Ecosanres Publication Series, Report Ecosanres, SEI. Stenström, Th.-A. (1996): Sjukdomsframkallande mikroorganismer i avloppssystem. NV, Socialstyrelsen och Smittskyddsinstitutet, Rapport 4683 In: Ridderstolpe, P. (2004): Introduction to Greywater Management. Ecosanres Publication Series, Report Ecosanres, SEI. SWEP (1982) Specifika föroreningar vid kommunal avloppsrening, Sedisk EPA, PM1964. (In Swedish) - In: Ridderstolpe, P. (2004): Introduction to Greywater Management. Ecosanres Publication Series, Report Ecosanres, SEI. Vinnerås, B. (2001): Faecal separation and urine diversion for nutrient management of household biodegradable waste and waste water. SLU. Report 244. In: Ridderstolpe, P. (2004): Introduction to Greywater Management. Ecosanres Publication Series, Report Ecosanres, SEI. Eriksson, Helena (2002): Potential and problems related to reuse of water in households, Env.&Resources DTU, Techn. Univ. of Denmark, Ph.D Thesis. In: Ridderstolpe, P. (2004): Introduction to Greywater Management. Ecosanres Publication Series, Report Ecosanres, SEI. Jenssen, P.D. (2001): ”Design and performance of ecological sanitation systems in Norway”, Paper at The First International Conference on Ecological Sanitation, Nanning, China. In: Jenssen, P.D., Greatorex, J.M, & Warner, W. S. (2004): Sustainable Wastewater Management in Urban Areas. = Kapitel 4. Kurs WH33, Konzeption Dezentralisierter Abwasserreinigung und Stoffstrommanagement. Universität Hannover. Jenssen, P.D., Greatorex, J.M, & Warner, W. S. (2004): Sustainable Wastewater Management in Urban Areas. = Kapitel 4. Kurs WH33, Konzeption Dezentralisierter Abwasserreinigung und Stoffstrommanagement. Universität Hannover. European Environment Agency EPA (2005): Indicator: Biochemical oxygen demand in rivers. Available at: (Accessed ) Siegrist, R.L., E.J. Tyler and P.D. Jenssen (2000): Design and performance of onsite wastewater soil absorption systems. Report presented at National Research Needs Conference Risk-Based Decision Making for Onsite Wastewater Treatment, St. Louis, Missouri,19-20 May USEPA. – In: (29) WHO (2006). Jenssen, P.D. and R.L. Siegrist (1990): Technology assessment of wastewater treatment by soil infiltration systems. Wat. Sci. Tech., 22 (3/4) pp In: Jenssen, P.D., Greatorex, J.M, & Warner, W. S. (2004): Sustainable Wastewater Management in Urban Areas. = Kapitel 4. Kurs WH33, Konzeption Dezentralisierter Abwasserreinigung und Stoffstrommanagement. Universität Hannover.

++ References Engelbert, E. & Regan, W.R. (no year): A Lexicon for Alternate On-Site Wastewater Treatment Systems. College of Agricultural Sciences, U.S. Department of Agriculture, and Pennsylvania Counties. Available at: Accessed Crites, R., and G. Tchobanoglous (1998): Small and decentralized wastewater management systems. McGraw-Hill. Jenssen P.D. and A. Heistad (2000): Naturbaserte avløpsløsninger. Student text. Department of Mathematical Sciences and Technology, Norwegian University of Life Sciences, Aas Norway (in Norwegian). – In: (29) WHO (2006). Jenssen P.D., T. Mæhlum, T. Krogstad and Lasse Vråle (2005): Treatment Performance of Multistage Constructed Wetlands for Wastewater Treatment in Cold Climate. Accepted in the Journal of Environmental Science and Health. Vol 40 (6-7) – In: (29) WHO (2006). Zhu, T. (1998). Phosphorus and nitrogen removal in light-weight aggregate (LWA) constructed wetlands and intermittent filter systems. PhD Theses 1997:16, The Agricultural University of Norway. – In: (29) WHO (2006). Jenssen, P. D. and L. Vråle (2004): Greywater treatment in combined biofilter/constructed wetlands in cold climate In: C. Werner et al. (eds.). Ecosan – closing the loop. Proc. 2nd int. symp. ecological sanitation, Lübeck Apr , GTZ, Germany, pp: – In: (29) WHO (2006). Reed, S.C. (1993) Subsurface flow constructed wetlands – a technology assessment. USEPA report 832-R – In: (29) WHO (2006). Mara, DD (1998): Design Manual for Waste Stabilisation Ponds in Mediterranean Countries, Lagoon Technology International Ltd., England. – In: (29) WHO (2006). Ottoson, J. and T. A. Stenström (2002): Faecal contamination of greywater and associated microbial risks. Water Research, 37, In: Jenssen, P.D., Greatorex, J.M, & Warner, W. S. (2004): Sustainable Wastewater Management in Urban Areas. = Kapitel 4. Kurs WH33, Konzeption Dezentralisierter Abwasserreinigung und Stoffstrommanagement. Universität Hannover. Heistad, A., P.D. Jenssen and A.S. Frydenlund (2001): A new combined distribution and pretreatment unit for wastewater soil infiltration systems. In K. Mancl (ed.) Onsite wastewater treatment. Proc. Ninth Int. Conf. On Individual and Small Community Sewage Systems, ASAE. Nolde, E Greywater reuse in households – experience form Germany. Environmental Research Forum Vols. 5-6: Transtec Publ., Switzerland. In: Jenssen, P.D., Greatorex, J.M, & Warner, W. S. (2004): Sustainable Wastewater Management in Urban Areas. = Kapitel 4. Kurs WH33, Konzeption Dezentralisierter Abwasserreinigung und Stoffstrommanagement. Universität Hannover. SANIMAS (2005): Informed Choice Catalogue. PP-Presentation. BORDA, AUSAID.

++ References Noah, M Onsite Treatment Options: Matching the system to the site. Small Flows Quarterly, 2(1), Winter. In: Engelbert, E. & Regan, W.R. (no year): A Lexicon for Alternate On-Site Wastewater Treatment Systems. College of Agricultural Sciences, U.S. Department of Agriculture, and Pennsylvania Counties. Available at: Accessed Reardon, R.D.: Clearing the Water about Wastewater Treatment with Membranes. CDM Viewpoint Archive. Available at: (Accessed ) Westlie, L. (1997): Treatment of greywater from households and cottages in compact filters. (Rensing av gråvann i kompakte filtre for boliger og hytter). Report from the NAT-program, no. 140/97. Norwegian Centre for Soil and Environmental Research, Aas Norway (In Norwegian). – In: (29) WHO (2006). Jenssen, P. D. (2003): Improving water and sanitation by decentralized groundwater supply and infiltration. PP-Presentation. Department of Mathematical Sciences and Technology, Norwegian University of Life Sciences. WHO (2006). Guidelines for the safe use of wastewater, excreta and greywater. Volume 4: Excreta and greywater use in agriculture. Draft version. Zhang Y, Dube MA, McLean DD, Kates M., (2003): ”Biodiesel production from waste cooking oil: 1. Process design and technological assessment”. Bioresour Technol Aug; 89 (1): 1-16. Jenssen P. D. and Krogstad T. (2002) Design of constructed wetlands using phosphorus sorbing lightweight aggregate (LWA). In: Constructed wetlands for wastewater treatment in cold climates. Ü. Mander and P. D. Jenssen (eds.) Advances in Ecological Sciences, 11, pp: 259 – 271, WIT Press. Jenssen P. D., Mæhlum T. and Krogstad T. (1993). Potential use of constructed wetlands for wastewater treatment in northern environments. Wat. Sci.Tech., 28 (10), Heistad A., Vråle L., Paruch A. M., Adam K., Jenssen P. D. (2005). A high performance compact wastewater treatment system using lightweight aggregate In: Nutrient Management in Wastewater Treatment Processes and Recycle Streams, Proceedings of IWA Specialized International Conference, Krakow * Poland, pp Ottoson J. (2003). Hygiene aspects of greywater reuse. Licenciate Thesis. Royal Swedish Institute of Technology, Swedish Institute for Infectious Disease Control. TRITA-LWC LIC 2011. Browne W. and P.D. Jenssen (2005) Exceeding tertiary standards with a pond/reed bed system in Norway. Water Science & Technology Vol 51 No 9 pp Ødegaard, H: Fjerning av næringsstoffer ved Rensing av Avløpsvann. Tapir Forlag, 80p.

++ Abbreviations BOD Biochemical Oxygen Demand
RBC Rotating Biological Contactors SS Suspended Solids STE Septic Tank Effluent WSP Wastewater Stabilization Ponds

++ Glossary: Greywater
Greywater is only slightly polluted wastewaters from dishwashing, showers, laundry machines, water from sinks etc. Greywater makes up for the largest share of wastewater. Yellow water is either urine diluted with flushwater or pure urine. Urine contains most of the nutrients we excrete again, but only has a very low, if at all, pathogen count. However, we also excrete micro-pollutants or endocrine substances through urine. Brownwater refers to faeces mixed with (flushing) water, but no urine. Most of the pathogens and a high proportion but rather little of the nutrients are contained here. Blackwater is urine and faeces mixed with or without domestic wastewater from showers, washing machines, sinks etc. GREYWATER

++ Glossary: Biochemical Oxygen Demand (BOD)
Biochemical oxygen demand (BOD) is a measure of how much dissolved oxygen is being consumed as microbes break down organic matter. A high demand, therefore, can indicate that levels of dissolved oxygen are falling, with potentially dangerous implications for the river’s biodiversity. High biochemical oxygen demand can be caused by: high levels of organic pollution, caused usually by poorly treated wastewater high nitrate levels, which trigger high plant growth Both result in higher amounts of organic matter in the river. When this matter decays, the microbiological activity uses up the oxygen. Biochemical oxygen demand is therefore one of the main parameters used in the Urban Wastewater Treatment Directive for controlling discharges. Unsurprisingly, large rivers – where wastewater plants are more likely to be located – register higher levels of oxygen demand than smaller rivers. Improvements in wastewater management causes biochemical oxygen demand to fall in all sizes of rivers (10). BIOCHEMICAL OXYGEN DEMAND

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