Anaerobic-aerobic treatment of high-strength and recalcitrant textile dyeing effluents.

Eco-friendly treatment of complex textile and dyeing wastewaters poses a pressing environmental concern. An approach adopting different treatment paths and integrated anaerobic-aerobic processes for high-strength and recalcitrant textile dyeing wastewater was examined. The study demonstrated that over 97% of suspended solids (SS) and more than 70% of chemical oxygen demand (COD) were removed by polyaluminum chloride pre-coagulation of suede fabric dyeing stream. Up to 58% of COD and 83% of SS were removed through hydrolysis pretreatment of other low-strength streams. Notable COD removal of up to 99% from a feed of 20,862 mg COD/L was achieved by integrated anaerobic-aerobic treatment of high strength stream. Besides achieving high COD removal of 97%, the anaerobic granular sludge process demonstrated multi-faceted attributes, including high feed loading, smaller footprint, little sludge production, and good stability. The integrated anaerobic-aerobic treatment offers a robust and viable option for highly contaminated and recalcitrant textile dyeing wastewater.

Anaerobic-anoxic-oxic biological treatment of high-strength, highly recalcitrant polyphenylene sulfide wastewater.

This paper outlines an integrated anaerobic-anoxic-oxic (A2O) treatment scheme for high-strength, highly recalcitrant wastewater from the production of polyphenylene sulfide (PPS) resins and their composite chemicals. An integrated anaerobic granular sludge blanket (GSB) and anoxic-oxic (AO) reactor indicated that the A2O removed chemical oxygen demand (COD) of up to 7,043 mg/L with no adverse impact from high total dissolved solids (25,000 mg/L) on the GSB COD removal and effluent suspended solids. At a Total Kjeldahl Nitrogen (TKN) nitrification load of 0.11 g TKN/L.d and 400 mg NH3/L, almost 99 % of the NH3 was degraded with effluent NH3 < 5 mg/L, meeting the limit of 35 mg/L. High S2- levels of up to 1470 mg/L can be transformed through aerobic microbial degradation to meet a limit of 1.0 mg/L. With proper microbial acclimation and process designs, the integrated A2O scheme offers a resilient and robust treatment for high-strength recalcitrant PPS wastewater.

Laboratory trial and full-scale implementation of integrated anaerobic-aerobic treatment for high strength acrylic acid wastewater.

Sustainable treatment of highly polluting industrial wastewaters poses a challenge to many municipalities. This study presented treatment of a high strength inhibitory acrylic acid wastewater by integrated anaerobic-aerobic processes. A novel scheme integrating anaerobic granular sludge blanket (GSB) reactor, aerobic carrier biofilm (CBR) reactor and activated sludge reactor (ASR) was tested. The laboratory trial showed that the GSB was able to degrade exceptionally high chemical oxygen demand (COD up to 32,420 mg/L) acrylic acid wastewater laden with 5% waste oil. Operated under a high volumetric loading (VLR) rate of 21.6 g/L·d, the integrated GSB-CBR-ASB achieved 99% of COD removal, of which 90% were removed by the anaerobic process and 9% by the aerobic processes. Full-scale implementation indicated comparable performance with overall removal up to 99%, thus meeting the discharge limits of 500 mg COD/L of public sewer. The integrated scheme was effective in which the anaerobic GSB functioning as a prime degrader that degraded most of the pollutants, while the aerobic CBR-ASB serving as a polisher that removed the remaining COD. With adequate microbial acclimation and granulation, the novel integrated scheme offers a resilient and robust treatment system for high strength inhibitory acrylic acid wastewater.

Startup and performance of full-scale anaerobic granular sludge blanket reactor treating high strength inhibitory acrylic acid wastewater.

High strength inhibitory wastewaters from chemical industries are commonly treated by energy-intensive physicochemical methods. The present work examines the startup and performance of a full-scale anaerobic granular sludge blanket (GSB) plant for treatment of an inhibitory acrylic acid wastewater. From a performance test on chemical oxygen demand (COD) loading up to 9800 mg/L and 3074 kg/d, the GSB plant removed 95% of COD. Coupled with a two-stage aerobic effluent polishing unit, the integrated anaerobic-aerobic plant achieved a remarkable total COD removal of 98-99% at full design load. Final effluent ranging from 173 to 278 mg COD/L conformed to the public sewer limits of 500 mg/L. Acclimated microbes and granulation resulted in efficient degradation of the inhibitory wastewater. Adequate reactor and process designs are crucial for granulation and robust treatment. The anaerobic and aerobic processes complement each other as anaerobic prime degrader and aerobic polisher in the integrated processes.