Search results
Results from the WOW.Com Content Network
Activated sludge tank at Beckton sewage treatment plant, UK.The white bubbles are due to the diffused air aeration system. The activated sludge process is a type of biological wastewater treatment process for treating sewage or industrial wastewaters using aeration and a biological floc composed of bacteria and protozoa.
Mesophilic anaerobic digestion (MAD) is also a common method for treating sludge produced at sewage treatment plants. The sludge is fed into large tanks and held for a minimum of 12 days to allow the digestion process to perform the four stages necessary to digest the sludge. These are hydrolysis, acidogenesis, acetogenesis, and methanogenesis.
Extended aeration agitates all incoming waste in the sludge from a single clarifier. The combined sludge starts with a higher concentration of inert solids than typical secondary sludge and the longer mixing time required for digestion of primary solids in addition to dissolved organics produces aged sludge requiring greater mixing energy input per unit of waste oxidized.
The quantity or “age” of sludge within the tank is closely monitored, as this can have a marked effect on the treatment process. The sludge is allowed to settle until clear water is on the top 20 to 30 percent of the tank contents. The decanting stage most commonly involves the slow lowering of a scoop or “trough” into the basin.
Most commonly, the fresh sludge is continuously extracted from the bottom of a hopper-shaped tank by mechanical scrapers and passed to separate sludge-digestion tanks. In some treatment plants an Imhoff tank is used: sludge settles through a slot into the lower story or digestion chamber, where it is decomposed by anaerobic bacteria, resulting ...
Activated sludge tank at Beckton sewage treatment plant, UK. The white bubbles are due to the diffused air aeration system. The activated sludge process is a type of biological wastewater treatment process for treating sewage or industrial wastewaters using aeration and a biological floc composed of bacteria and protozoa.
In facultative ponds, sludge removal may be necessary only in intervals around 15 to 25 years. In maturation ponds, sludge accumulation is very low. [6] Sludge removal, also called desludging, may be done in two basic ways: (i) interrupting the operation of the pond for desludging or (ii) keeping the pond in operation while desludging. [6]
Agricultural wastewater treatment is a farm management agenda for controlling pollution from confined animal operations and from surface runoff that may be contaminated by chemicals in fertilizer, pesticides, animal slurry, crop residues or irrigation water. Agricultural wastewater treatment is required for continuous confined animal operations ...