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Waste Management Michael Broaders Disposal Of Dairy Sludge Joan GrayLorraine MitchellEdel Pierce.

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Presentation on theme: "Waste Management Michael Broaders Disposal Of Dairy Sludge Joan GrayLorraine MitchellEdel Pierce."— Presentation transcript:

1 Waste Management Michael Broaders Disposal Of Dairy Sludge Joan GrayLorraine MitchellEdel Pierce

2 How Dairy Sludge Arises Wastewater sludge is generated at milk processing facilities after milk is processed into butter, cheese and other products. Wastewater sludge is generated at milk processing facilities after milk is processed into butter, cheese and other products. The washings created from cleaning processes (pipes, tanks etc) sent to WWTP and the main by-product from this treatment process is sludge. The washings created from cleaning processes (pipes, tanks etc) sent to WWTP and the main by-product from this treatment process is sludge. The dairy industry consumes 2 to 6 m 3 of water per tonne of milk entering the plant. The dairy industry consumes 2 to 6 m 3 of water per tonne of milk entering the plant. Over 75,000 tonnes of sludge is generated in Ireland from the treatment of wastewater from milk processing plants. Over 75,000 tonnes of sludge is generated in Ireland from the treatment of wastewater from milk processing plants. This sludge generated is predominantly land spread This sludge generated is predominantly land spread

3 Composition of dairy sludge Dairy sludge contain valuable nitrogen and phosphate although the nutrient content of potassium is low compared with conventional mineral fertilizers. Dairy sludge contain valuable nitrogen and phosphate although the nutrient content of potassium is low compared with conventional mineral fertilizers. Dairy sludge contains high levels of N, P,K and organic matter. Dairy sludge contains high levels of N, P,K and organic matter. Dairy sludge has considerably higher fertilizer value than municipal sludge. Dairy sludge has considerably higher fertilizer value than municipal sludge. Differences in the fertilizer value of sludge from different kinds of dairy plants e.g. cheese factories have 50% more phosphorus than fresh milk dairies. Differences in the fertilizer value of sludge from different kinds of dairy plants e.g. cheese factories have 50% more phosphorus than fresh milk dairies. Dairy sludge has lower levels of heavy metals or other harmful components than sewage sludge. Dairy sludge has lower levels of heavy metals or other harmful components than sewage sludge.

4 The Various Treatments of Dairy Sludge Anaerobic Digestion Anaerobic Digestion Composting (vermicomposting) Composting (vermicomposting) Land Spreading Land Spreading Sea Disposal Sea Disposal Land Filling Land Filling Incineration Incineration Constructed Wetlands Constructed Wetlands Lime Stabilization Lime Stabilization

5 Anaerobic Digestion Anaerobic digestion is the breakdown of organic material by a microbial population that lives in an oxygen free environment. Anaerobic digestion is the breakdown of organic material by a microbial population that lives in an oxygen free environment. AD treats waste by converting putrid organic materials to carbon dioxide and methane gas (biogas can be used to produce electrical power and heat). AD treats waste by converting putrid organic materials to carbon dioxide and methane gas (biogas can be used to produce electrical power and heat). The conversion of solids to biogas leads to much smaller quantities of solids that must be disposed. The conversion of solids to biogas leads to much smaller quantities of solids that must be disposed.

6 Anaerobic Digestion cont Anaerobic digestion is carried out by a group of bacteria which work together to convert organic matter to gas and inorganic constituents. Anaerobic digestion is carried out by a group of bacteria which work together to convert organic matter to gas and inorganic constituents. The soluble organic materials that are produced through hydrolysis consists of sugars, fatty acids and amino acids are converted to carbon dioxide. The soluble organic materials that are produced through hydrolysis consists of sugars, fatty acids and amino acids are converted to carbon dioxide. Other groups of bacteria reduce hydrogen to produce ammonia, hydrogen sulphide and methane. Other groups of bacteria reduce hydrogen to produce ammonia, hydrogen sulphide and methane. A group of methanogens converts acetic acid to methane gas. A group of methanogens converts acetic acid to methane gas.

7 Advantages and Disadvantages of Anaerobic Digestion Advantages Advantages Recovery of biogas Recovery of biogas Reduction in the mass and volume of sludge Reduction in the mass and volume of sludge Reduced emissions of greenhouse gases Reduced emissions of greenhouse gases Disadvantages Disadvantages Relatively high capital costs Relatively high capital costs Long retention times Long retention times High polluted supernatant High polluted supernatant

8 Differences Between Composting and Vermicomosting Composting is an accelerated biooxidation of organic matter passing through a thermophilic stage (45 to 65°C) where microorganisms liberate heat, carbon dioxide and water Composting is an accelerated biooxidation of organic matter passing through a thermophilic stage (45 to 65°C) where microorganisms liberate heat, carbon dioxide and water Vermicomposting is also a biooxidation and stabilisation process of organic matter that, in contrast to composting, involves the joint action of earthworms and micororganisms and does not involve a thermophilic stage Vermicomposting is also a biooxidation and stabilisation process of organic matter that, in contrast to composting, involves the joint action of earthworms and micororganisms and does not involve a thermophilic stage

9 Composting Systems of Composting: Systems of Composting: -Windrow -Windrow -In-vessel -In-vessel -Continuous vertical reactors -Continuous vertical reactors -Horizontal reactors -Horizontal reactors

10 Vermicomposting Open systems based on beds or windrows on the ground containing materials up to 18 inches deep Open systems based on beds or windrows on the ground containing materials up to 18 inches deep -this is labour intensive, process organic wastes slowly -this is labour intensive, process organic wastes slowly Batch reactors are containers raised on legs above the ground Batch reactors are containers raised on legs above the ground -these can use manual loading and collection or completely automated and hydraulically driven continuous flow reactors -these can use manual loading and collection or completely automated and hydraulically driven continuous flow reactors

11 Advantages of Vermicomposting Organic wastes can be broken down and fragmented rapidly by earthworms, resulting in a stable non-toxic material with good structure which has potentially high economic value as a soil conditioner for plant growth Organic wastes can be broken down and fragmented rapidly by earthworms, resulting in a stable non-toxic material with good structure which has potentially high economic value as a soil conditioner for plant growth Vermicompost is a finely divided peat like materials with excellent structure, porosity, aeration, drainage and moisture-holding capacity Vermicompost is a finely divided peat like materials with excellent structure, porosity, aeration, drainage and moisture-holding capacity Vermicompost supplies a suitable mineral balance & improves nutrient availability Vermicompost supplies a suitable mineral balance & improves nutrient availability It provides a great reduction in waste bulk density It provides a great reduction in waste bulk density

12 Principles of Vemicomposting Certain species of earthworms can consume organic residuals very rapidly and fragment them into much finer particles by passing them through their gizzard Certain species of earthworms can consume organic residuals very rapidly and fragment them into much finer particles by passing them through their gizzard Earthworms derive their nourishment from the micororganisms that grow upon the organic materials Earthworms derive their nourishment from the micororganisms that grow upon the organic materials They have both roles of turning and maintaining the organics in an aerobic condition They have both roles of turning and maintaining the organics in an aerobic condition

13 Vermicomposting systems must be maintained at temperatures below 35ºC. Exposure to to temperatures above this, even for short periods, will kill them. Vermicomposting systems must be maintained at temperatures below 35ºC. Exposure to to temperatures above this, even for short periods, will kill them. Key to successful vermicomposting lies in adding materials to the surface of piles or beds in thin, sucessive layers so that heating does not become excessive Key to successful vermicomposting lies in adding materials to the surface of piles or beds in thin, sucessive layers so that heating does not become excessive The processing of organic materials occurs most rapidly at temperatures between 15-25ºC & moisture contents of 70-90% The processing of organic materials occurs most rapidly at temperatures between 15-25ºC & moisture contents of 70-90% Species of earthworm used: Eisenia fetida, Lumbricus rubellus, Eudrilus eugeniae, Perionyx excavatus Species of earthworm used: Eisenia fetida, Lumbricus rubellus, Eudrilus eugeniae, Perionyx excavatus

14 Landspreading The dairy industry consumes 2 to 6m 3 of water per tonne of milk entering the plant The dairy industry consumes 2 to 6m 3 of water per tonne of milk entering the plant The effluent produced is either spread directly on agricultural land or treated in an on-site or local mixed wastewater treatment plant The effluent produced is either spread directly on agricultural land or treated in an on-site or local mixed wastewater treatment plant Dairy sludge contains high levels of nitrogen, phosphorus, potassium and organic matter Dairy sludge contains high levels of nitrogen, phosphorus, potassium and organic matter

15 In the context of landspreading, the key elements of groundwater protection are In the context of landspreading, the key elements of groundwater protection are -groundwater vulnerability -groundwater vulnerability -groundwater resource underlying the proposed spreadlands -groundwater resource underlying the proposed spreadlands -response to the perceived risk -response to the perceived risk Groundwater is most at risk where the subsoils are absent or thin and in areas of karstic limestone Groundwater is most at risk where the subsoils are absent or thin and in areas of karstic limestone

16 Regionally Important Aquifers-must have a consistent minimum of 2m of soil/subsoil before landspreading takes place Regionally Important Aquifers-must have a consistent minimum of 2m of soil/subsoil before landspreading takes place Locally Important Aquifers & Poor Aquifers- must have a consistent minimum of 1m of soil/subsoil before landspreading takes place Locally Important Aquifers & Poor Aquifers- must have a consistent minimum of 1m of soil/subsoil before landspreading takes place No landspreading if vulnerability of groundwater source is classified as Extreme or High within Inner Protection Area No landspreading if vulnerability of groundwater source is classified as Extreme or High within Inner Protection Area

17 Buffer Zones for Landspreading of Organic Waste Sensitive buildings-200m Sensitive buildings-200m Dwelling houses-100m Dwelling houses-100m Karst features-30m Karst features-30m Lakes and main river channels-20m Lakes and main river channels-20m Small watercourses-10m Small watercourses-10m Domestic wells-50m Domestic wells-50m Public water supplies-300m Public water supplies-300m

18 Nutrient Management Plans The objective of NMP’s is to protect the quality of water resources by avoiding pollution from agriculture. The preparation of a NMP for a REPS scheme involves the following: The objective of NMP’s is to protect the quality of water resources by avoiding pollution from agriculture. The preparation of a NMP for a REPS scheme involves the following: - the planner shall identify current land use & areas of farm which nutrient application should be restricted - the planner shall identify current land use & areas of farm which nutrient application should be restricted -baseline soil fertility survey of the farm -baseline soil fertility survey of the farm -sampling areas shall be selected on the basis of such characteristics as soil type, previous cropping and fertilising history -sampling areas shall be selected on the basis of such characteristics as soil type, previous cropping and fertilising history

19 Other Methods of Disposal The following are not used in Ireland The following are not used in Ireland -Sea disposal-not legal since introduction of EU Urban Wastewater Directive in Sea disposal-not legal since introduction of EU Urban Wastewater Directive in Incineration -Incineration -Landfill -Landfill

20 Constructed Wetlands

21 Man-made purpose built wetland Man-made purpose built wetland Specially designed to treat wastewater by using various type of ecosystems and substrate to create the right biological environment. Specially designed to treat wastewater by using various type of ecosystems and substrate to create the right biological environment. Built to treat various types of wastewater such as Built to treat various types of wastewater such as Farm run-off, Industrial and Domestic wastes. Farm run-off, Industrial and Domestic wastes.

22 How Constructed Wetland work Sedimentation: plant stems reduces the flow of the water allow sediments in wastewater to be deposited in the marsh. Sedimentation: plant stems reduces the flow of the water allow sediments in wastewater to be deposited in the marsh. Bacterial Action: the leaves draw oxygen through the roots. Oxygen is released which allows micro-organisms to thrive in the roots zone of the marsh. All micro- organisms feed off the wastewater which plays a major role in the water cleaning process. Bacterial Action: the leaves draw oxygen through the roots. Oxygen is released which allows micro-organisms to thrive in the roots zone of the marsh. All micro- organisms feed off the wastewater which plays a major role in the water cleaning process.

23 Filtration: soil, roots zone, plant litter help to filter the pollutants. Filtration: soil, roots zone, plant litter help to filter the pollutants. Absorption: Attractive forces between particles in wastewater draws them together and settles to base of wetland. Absorption: Attractive forces between particles in wastewater draws them together and settles to base of wetland. Precipcation: of heavy metals to soil and plant material. Precipcation: of heavy metals to soil and plant material. Decompostion:Organic pollutants in the wastewater are oxidised and reduced in the treatment process. Decompostion:Organic pollutants in the wastewater are oxidised and reduced in the treatment process.

24 Advantages & Disadvantages Advantages Low energy cost. Low energy cost. Provides growth for plant life. Provides growth for plant life. High level of treatment is achieved. High level of treatment is achieved.Disadvantages Large area of land is required Large area of land is required No design and operating criteria in place. No design and operating criteria in place.

25 Examples of it use the Dairy Industry Ireland Cheese Industry Kilmeaden Co Waterford. Cheese Industry Kilmeaden Co Waterford. In 2000 Developed a wetland system to treat dairy wastes produced In 2000 Developed a wetland system to treat dairy wastes produced The objective of the plan was to create ecological affect and to reduce various organic pollutants. The objective of the plan was to create ecological affect and to reduce various organic pollutants. Monitoring of the system was done over a 3 year period. Monitoring of the system was done over a 3 year period. B.O.D,Nitrates,PO 4,Ammonia,pH,C.O.D,Conductivity. B.O.D,Nitrates,PO 4,Ammonia,pH,C.O.D,Conductivity.

26 Example of Constructed Wetland

27 Yearly % Reduction in B.O.D Lagoon Lagoon Lagoon

28 Yearly % Reduction in C.O.D Lagoon Lagoon Lagoon

29 Other Example of Constructed Wetlands in Ireland Tara Mines Tara Mines objective was to treat water containing sulphate and metals. Reduce sulphate content by 69%,64% lead & 98% Zinc. objective was to treat water containing sulphate and metals. Reduce sulphate content by 69%,64% lead & 98% Zinc.

30 Lime stabislation Addition of lime to sludge material, creates a high pH as a result. Addition of lime to sludge material, creates a high pH as a result. Stabilisation occurs as a result of the reaction between the lime & water. Stabilisation occurs as a result of the reaction between the lime & water. Produces a exothermic heat pasteurises the sludge. Produces a exothermic heat pasteurises the sludge.

31 Legislation in regard to Disposal of Dairy Wastes Waste Management Act 1996 Waste Management Act 1996 Nitrate Directive. Nitrate Directive. Urban Wastewater Directive. Urban Wastewater Directive. Sludge use in agriculture Sludge use in agriculture Water Framework Directive. Water Framework Directive.


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