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.

Anaerobic granulation: A review of granulation hypotheses, bioreactor designs and emerging green applications.

Successful installations and operation of many granulation-base treatment plants all over the world in the recent years are reported. A better knowledge towards reactor operation and system performance has led to a growing interest in the technology. While the technology is well accepted and abundant research work has been carried out, insight unfolding the granulation fundamentals and its engineering applications remains unclear. This paper presents a review of some major hypotheses describing the evolvement of anaerobic granules. A number of physico-chemical hypotheses based on thermodynamics and structural hypotheses incorporating microbial considerations for anaerobic granulation have been developed. Features of anaerobic granulation and bioreactor designs are also reviewed. Advances in granulation research with respect to hydrogen production, degradation of recalcitrant or toxic compounds and emissions mitigation are delineated. Prospects and challenges of anaerobic granulation in wastewater treatment are also outlined.