M. A. I. Juel; S. A. Syed; T. K. Dey
Abstract
Activated sludge process is feasible and extensively method used for biological treatment of sewage and industrial wastewaters. The system is usually designed based on the simplified hydraulic related parameters. But design of biological treatment system based on hydraulic considerations is not reasonable ...
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Activated sludge process is feasible and extensively method used for biological treatment of sewage and industrial wastewaters. The system is usually designed based on the simplified hydraulic related parameters. But design of biological treatment system based on hydraulic considerations is not reasonable to ensure efficient treatment due to the extensive variation in the composition of wastewater and also for complex nature of biochemical reactions occurring in the treatment processes. Hence kinetic approach can be an option for appropriate design of biological treatment systems rather than hydraulic parameters considerations. The present study is aimed to develop kinetic coefficients for the treatment of chrome-tannery wastewater using activated sludge process. A laboratory-scale treatment unit subsuming an aeration tank and a clarifier were used for this system. The treatment unit was operated continuously for 80 days by varying the hydraulic retention time from 3 to 12 days. BOD for both influent and effluent as well as mixed liquor volatile suspended solid (MLVSS) of aeration tank were determined at different retention time to yield data for kinetic coefficients. The substrate utilization rate coefficient (k) was 0.624 day−1 while the half velocity constant (KS) was 38.42 mg/L, yield coefficient (Y) was found to be 0.674 mgMLVSS/mgBOD and the endogenous decay coefficient (Kd) was found as 0.068 day-1. These coefficients can be utilized for the rational design of activated sludge system for the treatment of chrome tannery wastewater.
A. Ebrahimi; G. D. Najafpour
Abstract
Microorganisms play an important role in biological treatment processes. Biodegradable organic matter in wastewater would be removed completely by proper microbial consortia. The mixed culture is either generally present in the wastewater, or is introduced to the target wastewater by mixing it with domestic ...
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Microorganisms play an important role in biological treatment processes. Biodegradable organic matter in wastewater would be removed completely by proper microbial consortia. The mixed culture is either generally present in the wastewater, or is introduced to the target wastewater by mixing it with domestic wastewater or sewage sludge. However, pure cultures bioprocess may be used in certain cases for the removal of specific contaminants. In favorable environmental condition, microorganisms are capable of presenting high efficiency in destruction of pollutants. If environmental conditions such as nutrition, pH, temperature, dissolved oxygen, hydraulic and sludge retention time are suitable and consistent with the nature of process, microorganisms grow and remove organic pollutants through biochemical activities. The aim of this article was to investigate the performance and mechanism of various systems of suspended and attached growth; while the detail of process in different fabricated systems was evaluated. The advantages and disadvantages of NRBC, UASFF, UAPB and normal activated sludge process were discussed. Growth kinetics and COD removal of effluents were also investigated. The result indicated the combination of fluidized and fixed film has created active biogranules which were quite faster and more efficient in treatment of industrial wastewater.
