Traditional Activated Sludge Process Research Articles

The pilot study for oil refinery wastewater treatment using a gas–liquid–solid three-phase flow airlift loop bioreactor

Aerobic bio-treatment of the refinery wastewater was carried out in a 170 m 3 pilot-scale gas–liquid–solid three-phase flow airlift loop bioreactor (ALR) with a low ratio of height to diameter ( s), in which biological membrane replaced the activated sludge. The influences of pH value, air flow rate (AFR) and hydraulic residence time (HRT) on COD and ammonia nitrogen (NH 4–N) reductions were investigated and discussed. The optimum operation condition was obtained as pH value 7.0–8.0, AFR 3.2 m 3 air (m 3 liquid h) −1 and HRT 6.5 h. Under the optimum operation condition, the effluent COD and NH 4–N were lower than 100 and 15 mg L −1, respectively for more than 40 days, which have achieved the national primary discharge standard of PR China (GB 8978-1996). Furthermore, this pilot-scale airlift loop bioreactor generated only one-third of the sludge waste compared to the traditional activated sludge process.

A pilot study for oil refinery wastewater treatment using a fixed-film bioreactor

Biological treatment of industrial oil refinery wastewater is a well-established method for remediation of these wastes. We have designed a new bioreactor system to increase the efficiency of biological treatment systems by (1) allowing greater organic loads, (2) minimizing production of sludge waste by-products, and (3) increasing process stability and resistance to shock loading. A fixed-film bioreactor system was constructed with a highly porous polyurethane foam to incubate microorganisms at concentrations up to 8000 mg/l. The support frame of the bioreactor system was built from cylindrical plastic pall rings to form a packed bed of ‘mixed-media’. The frame support provides a high surface area-to-volume ratio (210 ft 2/ft 3), and reduces potential problems of plugging and channeling, distribution of air and water, and mass-transfer limitations. Performance data for fixed-film bioreactors with 8-h hydraulic retention time (HRT) demonstrated chemical oxygen demand (COD) removal rates of 85–90%, and near 100% degradation of phenol from industrial oil refinery wastewater. Furthermore, the pilot bioreactor only generated one-third of the sludge waste compared to the traditional activated sludge process.

Design and operation of a wastewater treatment plant treating low concentration of municipal wastewater

The Zhen'an Wastewater Treatment Plant in Foshan City, Guangdong Province, China is a newly built large municipal wastewater treatment plant in south China, situated in the southeast of the famous ancient Foshan City, has a treatment capacity of 100,000 m3/d, serves an area of 32 km2 and 220,000 P. E., occupies 7 ha area with a total investment of 220 million RMB (about 26.5 million U.S dollar), which was put into operation in December 1995. As it is difficult to design and operate the wastewater treatment plant because of the low organic concentration of its influent, the simplified A/O activated sludge process without primary treatment for simultaneous removal of phosphorus and ammonia nitrogen was employed to design the plant, by which, the wastewater is treated very well, with higher effluent quality than the traditional activated sludge process, while the capital and O/M costs are lower than the latter.

Design and operation of a wastewater treatment plant treating low concentration of municipal wastewater

The Zhen’an Wastewater Treatment Plant in Foshan City, Guangdong Province, China is a newly built large municipal wastewater treatment plant in south China, situated in the southeast of the famous ancient Foshan City, has a treatment capacity of 100,000 m3/d, serves an area of 32 km2 and 220,000 P. E., occupies 7 ha area with a total investment of 220 million RMB (about 26.5 million U.S dollars), which was put into operation in December 1995.As it is difficult to design and operate the wastewater treatment plant because of the low organic concentration of its influent, the simplified A/O activated sludge process without primary treatment for simultaneous removal of phosphorus and ammonia nitrogen was employed to design the plant, by which, the wastewater is treated very well, with higher effluent quality than the traditional activated sludge process, while the capital and O/M costs are lower than the latter.

A Study of Fibre Media Submerged Biological Aerated Filter-Activated Sludge Process (FM-AS) for Sewage Treatment

The FM-AS process is a two-stage aerobic process consisting of a submerged biological aerated filter packed with fibre media as the first stage and activated sludge as the second stage. A separation unit working on the principle of dissolved-air flotation is needed between the two stages to remove the solids and thereby maintain a suitable sludge age for nitrification in the second stage. The FM-AS process produces effluents with good qualities. The highest removal efficiencies, obtained with a hydraulic retention time of 4.6 hrs. and an operating temperature of 16°C, for BOD5. NH3-N and SS were 95%, 95% and 90% respectively. The economic evaluation suggests that the FM-AS process can be more cost effective than the traditional activated sludge process, particularly when used for upgrading.