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The aim of this study is to find out a sustainable and cost‐effective solution to manage hazardous shock loads from metal finishing and electro‐coating industry. Results indicated that the main sources of hazardous wastewater are coming from batch chemical cleaning of degreasing basin (CCDB) (pH 13) and contains very hazardous chemicals, batch chemical cleaning of phosphating basin (CCPB) (pH 1.03) and contains high concentrations of iron (2300 mg/L) and zinc (2400 mg/L) and degreasing basin contents (DBC). Different treatment approaches were investigated. Results indicated that mixing CCDB with CCPB at their actual discharge allowed to form a self‐coagulant of metal hydroxide which was utilized to treat the (DBC) followed by sedimentation. Removal efficiency of COD (87%), TSS (94%), and oil and grease (92%) were achieved. To compare the efficiency of this treatment approach, conventional chemical coagulation of DBC was carried out using FeCl3 but the amount was very high. In conclusion, results proved the advantage of using self‐coagulation to treat DBC since it eliminates the use of external chemicals and provides an integrated solution for the three main sources of hazardous pollutants. Practitioner points: The manuscript provide an innovative and sustainable solution to the shock loads of hazardous wastewater generated from metal finishing and E‐coating industry by utilizing iron‐rich wastewater from chemical cleaning of phosphating basin and alkaline wastewater from chemical cleaning of degreasing basin to produce metal hydroxide.The metal hydroxide was cost‐effective and technically effectively than external coagulant in treating highly polluted degreasing basin content at due discharge time.Iron‐rich wastewater could be used to produce self‐coagulant of iron hydroxide.Mixing iron rich wastewater and alkaline wastewater produce iron hydroxide.Iron hydroxide is cost‐effective in treating hazardous wastewater of degreasing basin. [ABSTRACT FROM AUTHOR]

Since anaerobic wastewater treatment is a nonlinear and complex biochemical process, reasonable monitoring and control are needed to keep it operating stably and efficiently. In this paper, a least-square support-vector machine (LS-SVM) was employed to construct models for the prediction of effluent chemical oxygen demand (COD) in an anaerobic wastewater treatment system. The result revealed that the performance of the steady-state model based on LS-SVM for predicting effluent COD was acceptable, with the maximum relative error (RE) of 11.45%, the mean average percentage error (MAPE) of 0.79% and the root mean square error (RMSE) of 3.08 when training, and the performance fell slightly when testing. Even though, the correlation coefficient value (R) between the predicted value and the actual value of 0.9752 could be achieved, which means this model can predict the variation of effluent COD in general. The dynamic-state models under three kinds of shock loads, which were concentration, hydraulic, and bicarbonate buffer absent, showed good forecasting performance, the correlation coefficient values (R) all excelled 0.99. Among these three shocks, the dynamic LS-SVM model under bicarbonate buffer absent shock achieved the optimal performance and followed by the dynamic-state model under hydraulic shock. This paper provides a meaningful reference to improve the monitoring level of the anaerobic wastewater treatment process. [ABSTRACT FROM AUTHOR]

Autotrophic nitrogen removal from ammonium-rich wastewaters by partial nitrification–anaerobic ammonia oxidation (PN–ANAMMOX) offers advantages such as energy and resources saving compared with conventional treatment. In view of substrate fluctuations in real applications, performance stability of PN–ANAMMOX was investigated in a new lab-scale internal-loop airlift bio-particle (ILAB) reactor. The response of steady-state reactor to substrate concentration shocks was evaluated at 439.49 mg N/L (shock A) and 489.49 mg N/L (shock B) for 0.5 hydraulic retention time (HRT) and 1.0 HRT respectively. Higher substrate concentrations such as 613.09 mg N/L (shock C) and 629.00 mg N/L (shock D) were also tested for 0.5 HRT and 1.0 HRT respectively. The intensity and duration of shocks (A–D) proportionately affected the disturbance, inertial and recovery phase of the reactor. However, the reactor showed resilience to substrate concentration shocks by tolerating higher pH and maintaining its primary functions in shocks. The inhibition of bio-reaction triggered by substrate concentration shocks was totally reversible and performance indicators returned to steady-state level soon after the end of shocks. The reactor demonstrated full recovery from all shocks with respective recovery time of 13 h, 18 h, 19 h and 23 h and it was capable of recovering 100% even from most disturbing shock D (629.00 mg N/L; 1.0 HRT). The effluent ammonium was sensitive parameter which shot up to 20.5 times the steady-state value and it could be used to monitor the reactor performance. The study results revealed that PN–ANAMMOX was robust and it was not prone to temporary adverse effects of substrate concentration shocks. [ABSTRACT FROM AUTHOR]

This study evaluated the influence of clinoptilolite on the performance of activated sludge system shocked by high concentration of ammonium. The ammonium and chemical oxygen demand (COD) removal from the experimental reactor containing clinoptilolite and from the clinoptilolite-free control reactor was determined. The ammonium and COD removal was approximately 8 and 20% higher in the experimental reactor than in the control reactor, respectively. The removal increased with an increase in clinoptilolite concentration over the tested range up to 50 mg L-1. The presence of clinoptilolite resulted in the sludge flocs being more compacted with smoother surfaces and edges. Molecular biological analysis revealed that clinoptilolite increased the DNA diversity, richness, and evenness of sludge microbes. The enhanced-performance activated sludge previously treated with clinoptilolite was less influenced by the shock of ammonium than non-treated sludge in terms of the ammonium and COD removal. These results suggest that clinoptilolite enhanced the performance of activated sludge system in the removal of ammonium and COD. Amendment of activated sludge with natural zeolites may thus improve the efficiency of wastewater treatment. [ABSTRACT FROM AUTHOR]