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关键词：垃圾渗滤液 UASB+CASS组合工艺 氨氮吹脱 混凝沉淀 污泥浓缩
The design of a landfill leachate treatment process
General description of design: The task of the design is to complete the design of a landfill leachate treatment process and draw the diagram of process flow, the diagram of layout and so on. The requirements of the design are: a landfill waste disposal size is about 1200t / d. According to the local climate and topography, the size of its sewage treatment is 300m3 / d and the effluent quality is: CODcr: 6000mg / L,BOD5: 2500mg / L, NH3-N: 320 mg / L. Treated water quality requirements are: CODcr ≤ 100mg / L , BOD5: 30mg / L, NH3-N ≤ 25 mg / L, SS ≤ 30mg / L.
The standards of the design are: “design text book”, "engineering data”, “Landfill pollution control standard” (GB16889-2008), “Sewage Treatment Plant Process Design Manual”,“Drainage Manual”.
The principles of the design:
(1) Adopting advanced, rational, mature and reliable processing technology and equipment, to the maximum extent possible to play the investment efficiency, stable and efficient water treatment facilities and structures, as much as possible to reduce the project cost for the wastewater quality characteristics;
(2) The design of process and equipment selection in the production process with greater flexibility and room for adjustment to adapt to changes in water quality and quantity, to ensure the stability of water quality and can discharge standards;
(3) Handling facilities and equipment applicable, consider the operation automation, reduce labor intensity, and ease of operation and maintenance;
(4) Building structures is reasonably arranged, smooth, and reduce noise, eliminate odors, and improve the surrounding environment;
(5) Strictly enforce the relevant provisions of the State Environmental Protection, in accordance with the prescribed emission standards, so that treated wastewater to the water quality objectives and better than the emission standards.
Landfill leachate is a toxic effluent of a decomposing landfill that is produced when rainwater percolates through the landfill leaching out contaminants and pollutants. High concentrations of leachate organic content, high ammonia content, and, depending on the landfill of time, the content of each component in the leachate have a greater change, and by the climate, the seasons.Landfill leachate can be regarded as a high strength wastewater with acute and chronic toxicity. Its composition will vary from site-to-site, depending on many factors including; the nature of the waste in the landfill, the filling method, the level of compaction, the engineering design of the landfill, the rainfall of the region, and the stage of decomposition of the waste . Untreated leachate can percolate through the soil, mix with surface or permeate through the ground water and can contribute to the pollution of soil, surface and ground water.
To do the requirements of the standards general need different types process combination method to deal with the landfill leachate. Different types of combination method is usually use biological method or worked as a preprocessing , then use chemical method as a post-processing.
The pretreatment general package to expand the solid-liquid separation, flotation, air stripping, adsorption, precipitation, coagulation, etc.. The solid-liquid separation can effectively remove suspended solids by air stripping for ammonia removal efficiency higher.
The first set grille design is to remove coarse suspended solids, and in regulating the pool alkali stripping, removal of most of the ammonia and some organic. The main role of the secondary biological treatment is to removal the colloidal and dissolved organic pollutants in sewage effluent organic content of the emissions requirements. The biochemical treatment includes activated sludge and bio film. In this design, we use UASB + CASS process, This kind of design can be effectively removed the organic matter in leachate, suspended solids and ammonia nitrogen. The depth of processing primary role is to further remove impurities in conventional secondary treatment can not completely remove the sewage, sewage recycling and reuse. Advanced treatment includes membrane separation, coagulation, ion exchange and activated carbon adsorption. Coagulation and sedimentation,Disinfection process design is to remove refractory organics, handle better and improve water quality.