《环境工程概论》课程教学资源（PPT课件讲稿）（英语版）Chapter 8 Attached Growth Biological Treatment Processes

8 Attached Growth Biological Treatment Processes 8-1 Background Nonsubmerged attached growth processes A trickling filter is a nonsubmerged fixed-film biological reactor using rock or plastic packing over which wastewater is distributed continously

8 Attached Growth Biological Treatment Processes 8-1 Background Nonsubmerged Attached Growth Processes A trickling filter is a nonsubmerged fixed-film biological reactor using rock or plastic packing over which wastewater is distributed continously

The limitations of the trickling filter included a relatively high incidence of clogging, the long rest period required headloss, and the relatively low loading that could be used

The limitations of the trickling filter included a relatively high incidence of clogging, the long rest period required, headloss, and the relatively low loading that could be used

In the 1950s, plastic packing began to replace rock, which allowed the use of higher loading rates and taller filters(also known as biotowers)with less land area improved process efficiency, and reduced clogging In the 1960s, practical designs were developed for rotating biological contactors (RBCS), where the packing is rotated in the wastewater treatment tank Both trickling filters and rBCs have been used as aerobic attached growth processes for BOd removal only, combined BOD removal and nitrification

In the 1950s, plastic packing began to replace rock,which allowed the use of higher loading rates and taller filters (also known as biotowers) with less land area, improved process efficiency, and reduced clogging. In the 1960s, practical designs were developed for rotating biological contactors (RBCs), where the packing is rotated in the wastewater treatment tank. Both trickling filters and RBCs have been used as aerobic attached growth processes for BOD removal only, combined BOD removal and nitrification

In comparison to the activated-sludge process, disadvantages encountered for trickling filters are a poorer effluent quality in terms of BOD and TSS concentrations, greater sensitivity to lower temperatures, odor production, and uncontrolled solids sloughing events Trickling filters and rBCs have also been used in combined processes with activated sludge to utilize the benefits of both processes, in terms of energy savings and effluent quality

In comparison to the activated-sludge process, disadvantages encountered for trickling filters are a poorer effluent quality in terms of BOD and TSS concentrations, greater sensitivity to lower temperatures, odor production, and uncontrolled solids sloughing events. Trickling filters and RBCs have also been used in combined processes with activated sludge to utilize the benefits of both processes, in terms of energy savings and effluent quality

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8-2 Trickling Filters The depth of the rock packing ranges from 0.9 to 2.5 m and averages 1.8 m. Rock filter beds are usually circular, and the liquid wastewater is distributed over the top of the bed by a rotary distributor

8-2 Trickling Filters The depth of the rock packing ranges from 0.9 to 2.5 m and averages 1.8 m. Rock filter beds are usually circular, and the liquid wastewater is distributed over the top of the bed by a rotary distributor

Trickling filters that use plastic packing have been built in round, square, and other shapes with depths varying from 4 to 12 m In addition to the packing, other components of the trickling filter include a wastewater dosing or application system,an underdrain. and a structure to contain the packing. The underdrain system is important both for collecting the trickling filter effluent liquid and as a porous structure through which air can circulate

Trickling filters that use plastic packing have been built in round, square, and other shapes with depths varying from 4 to 12 m. In addition to the packing, other components of the trickling filter include a wastewater dosing or application system, an underdrain, and a structure to contain the packing. The underdrain system is important both for collecting the trickling filter effluent liquid and as a porous structure through which air can circulate

In practice, a portion of the liquid collected in the underdrain system or the settled effluent is recycled to the trickling filter feed flow, usually to dilute the strength of the incoming wastewater and to maintain enough wetting to keep the biological slime layer moist

In practice, a portion of the liquid collected in the underdrain system or the settled effluent is recycled to the trickling filter feed flow, usually to dilute the strength of the incoming wastewater and to maintain enough wetting to keep the biological slime layer moist

Distributor arms extend across the trickling filter inner diameter and have variable openings to provide a uniform application rate per unit area. The distributor arms are rotated by the force of the water exiting through their opening or by the use of electric drives In some cases, especially for square or rectangular filters, fixed flat-spray nozzles have been used

Distributor arms extend across the trickling filter inner diameter and have variable openings to provide a uniform application rate per unit area. The distributor arms are rotated by the force of the water exiting through their opening or by the use of electric drives. In some cases, especially for square or rectangular filters, fixed flat-spray nozzles have been used

Primary clarification is necessary before rock trickling filters In some installations a wire-mesh screen is placed over the top of plastic packing to collect debris that can be vacuumed off periodically. The biological community in the filter includes aerobic and facultative bacteria fungi, algae, and protozoans. Higher animals. such as worms. insect larvae. and snails are also present

Primary clarification is necessary before rock trickling filters. In some installations, a wire-mesh screen is placed over the top of plastic packing to collect debris that can be vacuumed off periodically. The biological community in the filter includes aerobic and facultative bacteria, fungi, algae, and protozoans. Higher animals, such as worms, insect larvae, and snails, are also present