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Living microorganisms consume organic material in wastes, and use its energy to sustain normal activities, to grow, and to reproduce. A biological process, either natural or artificial, involves biochemical reactions, nutrient balance, microbial population balance, and waste disposal. This chapter introduces biological concepts for environmental control processes. The specific topics covered include:...
Various land application technologies as means for waste treatment and disposal are introduced. This chapter discusses the engineering topics of: surface spreading, overland flow, infiltration, percolation, slow rate irrigation, crop irrigation, vegetative cover, soil adsorption, soil ion exchange, mineralization, bacteriological activity, waste treatment, water removal, nitrogen removal, phosphorus...
There are two major components of a subsurface wastewater treatment system: (a) a pretreatment tank for gravity separation and accumulation of the settleable solids from the wastewater, and (b) subsurface distribution and final treatment of the supernatant liquid from this pretreatment tank. This chapter covers the topics of subsurface waste treatment theory, anaerobic septic tank, aerobic tank, subsurface...
Submerged aeration is created by the action of submerged aerators (air diffuser, static mixer, sparge turbine, jet aerator, etc.), which introduce compressed air or oxygen at or near the bottom of an aeration basin. Oxygen transfer and liquid mixing are achieved as air/oxygen bubbles rise to the water surface. This chapter discusses the topics of aeration performance, oxygenation, deoxygenation, oxygen...
urface aeration involves the use of special floating aerators or spray aerators for removing taste/odor-causing substances, carbon dioxide, hydrogen sulfide, methane, volatile organic compounds, etc. from water, and for oxidizing iron and manganese in drinking water. The topics covered in this chapter are: gas solubility, diffusion, equilibrium, mixing, gas transfer, reaeration, instream aeration,...
Activated sludge consists of suspended biological flocs that are matrices of microorganisms, nonliving organic matter and inorganic materials. The activated sludge or biological flocs mix with the waste stream, oxidize the organic substances in the wastewater in the presence of oxygen for bio-oxidation and nitrification reactions, or in the absence of oxygen for denitrification reaction. This chapter...
The use of pure oxygen for activated sludge treatment has become competitive with the use of air owing to the development of efficient oxygen dissolution systems. The pure oxygen system may be used for aeration in activated sludge systems that operate in either the plug flow or complete mix hydraulic regimes. It is readily adaptable to new or existing complete mix systems and can be used to upgrade...
One of the simplest forms of biological treatment processes is the stabilization pond or stabilization lagoon. It is also the most common industrial wastewater treatment facility. This versatile installation serves many basic purposes, including: (a) storage or impoundment of wastewater; (b) settling and removal of suspended solids; (c) storage or impoundment of settled solids; (d) equalization; (e)...
Trickling filter consists of a fixed biological bed of rock media or plastic media on which wastewater is applied for aerobic biological treatment. Biological slimes form on the media which assimilate and oxidize substances in the wastewater. This chapter introduces the historical development, recent advances, principles, applicability, microbiology, ecology, models, types, design criteria, and case...
Rotating biological contactor (RBC) is an attached-growth biological process, which consists of a series of rotating plastic media all coated with a layer of biofilm. The biofilm or slime on the media aerobically react with substances in a waste stream for bio-oxidation and nitrification, or anaerobically react with the substances for denitri-fication. This chapter discusses the theory, performance,...
A sequencing batch reactor (SBR) can be either a biological SBR (BIO-SBR) or a physicochemical SBR (PC-SBR). BIO-SBR includes traditional sedimentation biological SBR, innovative flotation biological SBR (BIO-DAF-SBR), innovative membrane biological SBR (MBR-SBR), aerobic digestion SBR (AD-SBR), etc. All PC-SBR are innovative processes including at least sedimentation PC-SBR (PC-SED-SBR), flotation...
An oxidation ditch is a modified activated sludge biological treatment process that uses long solids retention times (SRTs) to remove biodegradable organics. The typical oxidation ditch is equipped with aeration rotors or brushes that provide aeration and circulation. The wastewater moves through the ditch at 1 to 2ft/s. The ditch may be designed for continuous or intermittent operation. Because of...
If the wastewater to be treated contains various forms of nitrogen, three biological treatment steps are required for nitrogen removal: (a) in a bio-oxidation step, organic nitrogen is anerobically broken down to ammonia nitrogen; (b) in a subsequent nitrification step, ammonia nitrogen in the wastewater is aerobically converted to nitrate nitrogen; and (c) in a final denitrification step, nitrate...
Anaerobic digestion results in the biological breakdown of the sludge into methane, carbon dioxide, unusable immediate organics and a small amount of cellular protoplasm, under anaerobic conditions, mainly for sludge stabilization and volume reduction. This chapter introduces anaerobic digestion theory, biochemistry, microbiology, organic loading, temperature control, digester design, gas collection,...
Aerobic digestion is the biochemical oxidative stabilization of wastewater sludge in open or closed tanks that are separate from the liquid process system. This method of digestion is capable of handling waste activated, trickling filter, or primary sludges as well as mixtures of the same. Aerobic digestion is based upon endogenous respiration, where in the absence of suitable substrate food, microorganisms...
Composting is one of several methods for treating biosolids to create a marketable end product that is easy to handle, store, and use. The end product is usually a Class A, humuslike material without detectable levels of pathogens that can be applied as a soil conditioner and fertilizer to gardens, food and feed crops, and rangelands. This compost provides large quantities of organic matter and nutrients...
Vermistabilization, also known as vermicomposting, is a biodegradation process for stabilization of biosolids and organic solid wastes using earthworms. The worms maintain aerobic conditions in the organic substances and accelerate and enhance the biological decomposition of the organic substances. This chapter introduces and reviews the vermistabilization process. The technology development, technical...
Most of volatile organic compounds (VOC) and odor-causing organic substances in air streams are biodegradable, thus can be effectively removed by a gas-phase biological filter or a biological scrubber. The topics covered in this chapter include: odor classification, odor emission regulations, odor control technologies, biofilters, biological scrubbers, process control, monitoring, and biofiltration...
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