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September 25, 2013 1  Historical sewage treatment ◦ Washed away and diluted by rain and surface water ◦ Early human habitations were often built near.

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Presentation on theme: "September 25, 2013 1  Historical sewage treatment ◦ Washed away and diluted by rain and surface water ◦ Early human habitations were often built near."— Presentation transcript:


2 September 25, 2013 1

3  Historical sewage treatment ◦ Washed away and diluted by rain and surface water ◦ Early human habitations were often built near rivers or oceans for conveyance and sewage disposal  As population densities increased sewer collection and conveyance systems were developed. ◦ First sanitation system was found southeast of Iran, used in palaces in Crete, Greece (3,000 years old & still works) ◦ As populations rose, systems became more complex  Rome had complex sewer networks between 46BC-400AD 2

4  Most cities in early times had no sewers and relied on nearby rivers or occasional rain to wash away sewage. In some cities, waste water simply ran down the streets.  The growth of cities quickly caused polluted streets and became a constant source of disease. Even as recently as the late 1800’s street sewerage systems and individual cesspits were common.  Rain often caused the cesspits to overflow leaving the pavements awash with foul sewage and caused water-borne diseases such as cholera and typhoid. 3

5  Vinaigrette ◦ Containing aromatic herbs (sage, cinnamon, lavender, mint and rosemary) and mixed with alcohol and acetic acid to create a pleasant perfume ◦ Protection from foul odors ◦ It was believed at the time that they could protect one from cholera ◦ Used by both men and women, suspended from chatelaines, placed in pockets, hung from long chains, bracelets or finger rings. ◦ Often designed in the shape of a rectangular box, and often made from multicolored gold or silver 4

6  Because of the Industrial Revolution, populations in European and North American cities grew rapidly  Often led to crowding and increasing concerns about public health  Many cities developed municipal sanitation programs and constructed extensive sewer systems to help control outbreaks of disease in the late 19th and early 20th centuries 5

7  Initially these systems discharged sewage directly to surface water, without treatment  Water pollution became a concern so cities added sewage treatment  Rural American families and many in towns and small cities: ◦ Outhouses were common until about 50 years ago ◦ Then, septic systems became common and added:  Convenience  Public health  Environmental protection 6 Ag Research facility Niger, August, 2007

8  About a third of all Indiana homes use septic systems  Septic systems remove pathogens from wastewater ◦ Shigella ◦ Giardia ◦ Escherichia coli (E. coli)  Most (~ 85%) of these systems are conventional septic-absorption fields 7

9  Typical Systems ◦ Wastewater is drained in a septic tank ◦ Grease and oils rise to the top ◦ Solids settle to the bottom where they decompose  The clarified effluent is channeled to an absorption field. 8

10 9 Sewage from Home Vent Sludge Layer Liquid Layer Scum Layer Tank care: septic tanks should be pumped every 3-5 years

11 10 Conventional Onsite Dispersal System Soil Absorption Field Septic Tank Distribution box

12  Soils effectively treat effluent through the following processes ◦ Chemical ◦ Physical ◦ Biological  The best soil for an absorption field is a deep, well-drained soil  Oxygenated soil is necessary for waste degradation 11

13  Soil texture and structure affects the speed that water moves through soil  Problems for absorption fields: ◦ High water tables ◦ Dense or impermeable subsoil (transmit water too slow) ◦ Sandy soils (transmit water too fast)  Prime Ag land (land that is good for crop production) usually does not make a good septic absorption field.  58% of Indiana is considered prime Ag land, second only to Illinois at 59%. (IA=52%, OH & KS=45%) 12

14  Soil A is well drained (oxygen rich) and suitable for a conventional trench septic system.  Soil C is poorly drained (oxygen deprived) and saturated with water most of the time.  Soil B is saturated briefly during the year.  Soils B and C are unsuitable for conventional trench septic systems. 13

15 14 This map shows the percent of land that is estimated as unsuitable for conventional onsite (septic) systems, unless the site or the system is modified.

16  Prior to 1977 ◦ No septic system regulations in Indiana (construction or placement) ◦ Construction practices varied widely  Current Standards ◦ Wastewater must not:  Contaminate groundwater  Contaminate surface water  Interfere with household plumbing 15

17 Conserve water to avoid overloading your septic system Toilets ◦ 1992 US Energy Policy and Conservation Act requires 1.6 gallon/flush “ultra low-flow toilets” ◦ 2007: US government is now promoting 1.3 gal/flush toilets Do not use caustic drain openers for a clogged drain (use boiling water or a drain snake to open clogs) More to follow… 16

18 Cleaners Use commercial bathroom cleaners and laundry detergents in moderation. Use a mild detergent or baking soda when possible. Do not flush anything other than human wastes and septic safe toilet paper (no diapers, medications, etc…. Your septic system is not a trash can) Do not use a garbage disposal (compost instead) More to follow… 17

19 Avoid dumping grease or fats down your kitchen drain Keep latex paint, varnishes, thinners, waste oil, photographic solutions, pesticides, or other hazardous chemicals out of your septic system  Do not use septic tank additives, commercial septic tank cleanser, yeast, sugar, etc. ◦ These products are not necessary and some may be harmful to your septic system 18

20  Water from roof drains, basement drainage sump pumps, hot tubs, and swimming pools should not enter the septic system  According to Indiana state regulations: ◦ Water softener backwash must be treated as sewage ◦ Water wasted from reverse osmosis water treatment must also be treated as sewage. 19

21 Treatment and percolation of wastewater depends on presence of 24” of undisturbed, uncompacted, unsaturated soil below the trench Never allow anything heavier than a riding lawnmower on soil absorption area. Heavy vehicles on the drain field before, during, or after construction and when the soil is saturated can damage soil’s ability to absorb wastewater Compaction drives frost deep into the soil and prevents effective treatment in winter 20

22  Water conservation  Effluent filters  Lower high water tables with perimeter drains  Use elevated systems (e.g., sand mounds)  Shallow trenches  Use shallow drip irrigation (requires pre-treat)  Connect to existing central sewer system  Alternative sewer and cluster systems 21

23  Mound system  Effluent filters  Constructed subsurface wetlands  Recirculation media filters  Aeration treatment units  Drip irrigation  Cluster systems 22

24 BenefitsCosts  Allows use of septic systems in areas with poor soils, shallow bedrock, or high water tables  Operates in all climates More space needed Limited use on slopes Requires pump maintenance Higher installation cost than conventional absorption fields (~ $10,000) 23

25 24 In Flow Septic Tank Out Flow Sludge Riser Effluent Filter

26 25  Protects disposal field from solids overflow  Requires routine maintenance  Additional cost for installation

27 26

28  Question: Why is routine maintenance especially important to people with an effluent filter? 27

29 28 Septic Tank Soil Absorption Field Pump Chamber Constructed Wetland

30 29 Home Septic Tank Cleanouts Constructed Wetland Level Adjust Sump Disposal Field

31 BenefitsCosts Works for both large, continuous flows and for individual residences  Relatively large land area required, 150 sq ft/bedroom  Requires regular maintenance and monitoring  Affected, but only slightly, by seasons 30

32 31 Septic Tank Soil Absorption Field Recirculation Tank (recirculating)

33 32 2” sand around 1/2” plywood box 2 feet sand From tank 1” of 1/4” gravel 3/4”-1”gravel (5” deep, mound over pipe) 4” PVC pipe underdrain 3/8” pea gravel (3” deep) Drain pipe to recirculation tank or absorption field 1” dia. pressurized pipe 2’ apart with 1/8” holes 2’ o.c. orifice shield Manifold 2” of 3/4-1” gravel

34 33 Sand, Gravel, Peat

35 34

36 BenefitsCosts  Limited area needed for the absorption field (about 30 ft 2 per bedroom)  Can replace a failed conventional absorption field when there is not enough room for a new one  Can be used with high groundwater, shallow bedrock, poor soils, or other site restrictions  Will keep N out of groundwater  These systems are more expensive, so they are generally used only when necessary and centralized treatment unavailable or too expensive 35

37 36

38 BenefitsCosts  Often used to renovate failing systems in other states  Effective when ATU is placed before a septic tank or an effluent filter is used after ATU to keep solids out of absorption field in case of malfunction (overflow must go to the soil absorption area)  Relatively inexpensive to install  Electricity and alarm required (relatively costly to power aerator)  Professional maintenance required every 3-6 months  Widely fluctuating flows can cause problems. 37

39 38  Frequent application of small quantities of wastewater just below soil surface with applicators along distribution line (less than 1 gal/hr per ft of pipe)  Drip systems have been used in agriculture for 30 years

40 39

41 Benefits  Easy to design and install  Wastewater is slowly and uniformly distributed over the entire absorption area  More water moves laterally through capillary action, reducing deep percolation so the wastewater is placed in biologically active soil  Only 12” deep so helps overcome limitations of seasonal high water tables & slow permeability  Water and nutrients can be reused by vegetation  Reduces nitrogen percolation to groundwater  Can be used on very steep slopes (with pressure compensators) 40 98% of soil biological activity is in top 16” of soil.

42 Costs  More expensive (pipe with drip emitter is 50-60 cents/ft)  Potential plugging problems.  Higher operational cost  Maintenance needed 3-4 times/year  Septic tank effluent must be treated and filtered before drip disposal 41

43 42  Cluster System ◦ Collective household sewage treatment and disposal ◦ Collaboration between multiple neighboring homes ◦ Requires a large soil absorption area for treatment  Typically used in areas with poor soil conditions or where home lots are too small for replacement systems.  The central disposal site must be carefully selected to handle the large flow

44 BenefitsCosts Cheaper than large diameter sewers, central treatment and discharge systems  More costly than individual septic systems to install (but cost/family generally much less)  No Indiana cost-share  A mechanism must be set up to manage and collect costs (installation and continuing maintenance)  Rural families and regulators are not familiar with it 43

45  Primary treatment ◦ Separates large solids from the waste stream, using metal grates and a grit tank ◦ The waste stream goes to the primary sedimentation tank where about half the suspended, organic solids settle out  Secondary treatment ◦ A trickling filter bed, aeration tank, or sewage lagoon ◦ Biologically degrades dissolved organic compounds 44

46  Tertiary treatment ◦ Removes plant nutrients (especially nitrates and phosphates) 45 Primary treatment Secondary treatment Tertiary treatment Primary sedimentation tank sand gravel Organic solids trickling filter bed, aeration tank, or sewage lagoon biological degradation of the dissolved organic compounds removes plant nutrients, especially nitrates and phosphates

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