Commonly used aerobic biological treatment methods include activated sludge process, deep well aeration process, adsorption biodegradation process (AB process), contact oxidation process, sequencing batch reactor (SBR) process, and circulating activated sludge process (CASS process).
(1) Biological Contact Oxidation Process: This technology combines the advantages of activated sludge and biofilm processes, featuring high volumetric loading, low sludge production, strong shock resistance, stable process operation, and convenient management. Many projects use a two-stage process to acclimate dominant microbial species at different stages, fully utilize the synergistic effect between different microbial populations, and improve biochemical efficiency and shock resistance. In engineering projects, anaerobic digestion and acidification are often used as pretreatment steps, and contact oxidation is used to treat pharmaceutical wastewater.
(2) Deep Well Aeration Process: Deep well aeration is a high-speed activated sludge system. This method has advantages such as high oxygen utilization rate, small footprint, good treatment effect, low investment, low operating cost, no sludge bulking, and low sludge production. In addition, it has good heat preservation effect and is not affected by climate conditions, which can ensure the treatment effect of wastewater in northern regions during winter. After the high-concentration organic wastewater is treated by deep aeration tank, the COD removal rate reaches 93.5%, which shows that its treatment efficiency is very high and it is extremely beneficial to the next step of treatment, playing a decisive role in the effluent compliance of the process treatment.
(3) SBR method The SBR method has the advantages of strong resistance to shock load, high sludge activity, simple structure, no need for recirculation, flexible operation, small footprint, low investment, stable operation, high matrix removal rate, and good ammonia and phosphorus removal effect. It is suitable for treating wastewater with large fluctuations in water volume and quality. The experiment of treating pharmaceutical wastewater by SBR process shows that: the aeration time has a great influence on the treatment effect of the process; setting an anoxic section, especially the alternating design of anoxic and aerobic, can significantly improve the treatment effect; the SBR enhanced treatment process with PAC added to the reaction tank can significantly improve the removal effect of the system. In recent years, this technology has become increasingly sophisticated and is widely used in pharmaceutical wastewater treatment. The hydrolysis-acidification-SBR method is used to treat biopharmaceutical wastewater, achieving effluent quality that meets the GB8978-1996 standard.
(4) AB Method The AB method is an ultra-high load activated sludge process. The AB process generally achieves higher removal rates of BOD5, COD, SS, phosphorus, and ammonia than conventional activated sludge processes. Its outstanding advantages include high A-stage load, strong resistance to shock loads, and a significant buffering effect on pH and toxic substances, making it particularly suitable for treating wastewater with high concentrations and significant variations in water quality. The hydrolysis-acidification-AB biological process for treating antibiotic wastewater has a short process flow, is energy-efficient, and has lower treatment costs than the chemical flocculation-biological treatment method for the same type of wastewater.
