O/H/H/O Process for Total Nitrogen Removal: An Upgrade of the A/A/O Process for Coking Wastewater Treatment

Abstract

For industrial wastewater with high chemical oxygen demand (COD) and nitrogen, traditional wastewater treatment processes fail to achieve stable removal of typical pollutants under the conditions of variable raw water quality and low energy consumption. In this study, a novel pre-and post-physicochemical synergistic oxic−hydrolytic and denitrification−hydrolytic and denitrification−oxic (P2PC-O/H/H/O) process with in situ sludge separation in respective bioreactors was developed, in which signature pollutants and TN were completely removed through an optimized allocation of energy and carbon source. The 180-day full-scale operation showed that optimal removal of COD and TN (with removal rates of 97.5 and 94.5%, respectively) can be obtained at influent loading rates of 1.5−1.7 kg COD (m 3 days) −1 and 0.11−0.13 kg TN (m 3 days) −1 . In this process, O1 reactor ensured organic matter removal and pre-nitrification. Double H (H1 and H2) reactors allowed deep removal of TN through combined and coupled denitrification pathways. O2 reactor consolidated the overall treatment performance through decarbonization and nitrification. By P2PC, the refractory and easily biodegradable total organic carbon (TOC) was separated, achieving a qualitative and fractional utilization of electron donors. Analysis of the microbial community in the whole process indicated that Nitrosomonas (0.7−2.4%) and Nitrospira (0.3−1.7%) played a major role in nitrification. Ottowia (15.4−19.6%) and Limnobacter (1.8−7.4%) dominated in eliminating organic matter. The P2PC-O/H/H/O process with a four-sludge regime enabled a spatial allocation of functional microorganisms. The operation cost of the full-scale process was approximately 1.335 USD m −3 . In short, this P2PC-O/H/H/O process, with high efficiency and stability in signature pollutant removal, will be a promising wastewater treatment technology to revolutionize the existing anaerobic− anoxic−oxic (A/A/O) process, adding a new dimension to industrial wastewater management.

Function and Direction of Cyanide in Coking Wastewater: From Water Treatment to Environmental Migration

“…This is because Fe 2+ /Fe 3+ ions can reduce the biological toxicity of cyanide (the LD 50 of [Fe­(CN)] 6 4– and Prussian blue are 6.4 and 8.0 g/kg, respectively, which are significantly higher than that of CN – ), even if its chemical properties are more stable . The metabolic pathway was determined by the distribution of microbial function in different unit reactors . In the OHHO system, the metabolic pathways of cyanide in the H1 unit were cyanate metabolism and formamide metabolism.…”

“…In general, wastewater treatment processes include anaerobic–oxic (AO), anaerobic–anoxic–oxic (AAO), and anoxic–oxic–oxic (AOO). However, our previous research studies ,, have proved that the above processes could not well resist the toxicity of coking wastewater, leading to very low removal rates of organic matter in the unit A (anaerobic). In addition, the traditional reflux denitrification method can bring about disorders of the biological system and thus limits the complete removal of total nitrogen .…”

“…However, our previous research studies ,, have proved that the above processes could not well resist the toxicity of coking wastewater, leading to very low removal rates of organic matter in the unit A (anaerobic). In addition, the traditional reflux denitrification method can bring about disorders of the biological system and thus limits the complete removal of total nitrogen . In this case, our research group developed a multifunctional microbial fluidized bed wastewater treatment reactor system with coupled mixing-reaction-separation (named: all-purpose microbial and pneumohydraulic in situ coupling water treatment system, AMPhIX) as the basic structure.…”

“…In this case, our research group developed a multifunctional microbial fluidized bed wastewater treatment reactor system with coupled mixing-reaction-separation (named: all-purpose microbial and pneumohydraulic in situ coupling water treatment system, AMPhIX) as the basic structure. Configured with changes in characteristic parameters, controls of the dissolved oxygen, and regulations of microbial functions, it is called the OHO or OHHO process equipped with double aerobic units combined with hydrolysis and denitrification. ,− Among these, O1 is a high-load aerobic reactor for high-efficiency COD removal and ammonia oxidation; H1 is a hydrolytic denitrifying reactor equipped with biological stuffing; H2 is a hydrolytic and advanced denitrifying reactor; and O2 is a complete nitrification/mineralization reactor. Numerous studies and practices ,,, have demonstrated that the OHHO system can effectively avoid toxicity inhibition, achieve near-zero discharge of total nitrogen with low energy and carbon source consumptions, coupling mainstream anaerobic ammonia oxidation and multiple denitrification modes with four independent sludge systems, and no reflux operation.…”

“…Configured with changes in characteristic parameters, controls of the dissolved oxygen, and regulations of microbial functions, it is called the OHO or OHHO process equipped with double aerobic units combined with hydrolysis and denitrification. ,− Among these, O1 is a high-load aerobic reactor for high-efficiency COD removal and ammonia oxidation; H1 is a hydrolytic denitrifying reactor equipped with biological stuffing; H2 is a hydrolytic and advanced denitrifying reactor; and O2 is a complete nitrification/mineralization reactor. Numerous studies and practices ,,, have demonstrated that the OHHO system can effectively avoid toxicity inhibition, achieve near-zero discharge of total nitrogen with low energy and carbon source consumptions, coupling mainstream anaerobic ammonia oxidation and multiple denitrification modes with four independent sludge systems, and no reflux operation. Besides, this system is particularly effective for the treatment of complex nitrogen-containing compounds (CN – /SCN – /ETDA/pyridine/quinoline/organic nitriles/aniline). , However, as of now, no detailed research has been reported on the distribution of cyanide in this process except for its resistance against a high cyanide concentration.…”