Simultaneous control of algal micropollutants based on ball-milled powdered activated carbon in combination with permanganate oxidation and coagulation.

This study reports application of KMnO4 pre-oxidation and engineered powdered activated carbon (PAC) adsorption to simultaneously control geosmin, 2-methylisoborneol (2-MIB), and microcystin-LR (MC-LR) in conventional drinking water treatment plants (DWTPs). Pulverization of commercial wood-based PAC (1 mm ZrO2 ball, 12 h) reduced the median size to ~6 µm and resulted in overall enhanced kinetics for adsorption of the algal micropollutants. A series of parametric experiments were performed to estimate minimal contact for KMnO4 (1 mg L-1, 10 minutes) and PAC (20 mg L-1, 40 minutes) prior to coagulation, with the aim to meet guidelines (0.02, 0.02, and 1 µg L-1 for geosmin, 2-MIB, and MC-LR, respectively) at specific influent concentrations (0.1, 0.1, and 100 µg L-1) in surface water matrix. Ball-milling of parent PAC with a low oxygen content (~2.5 w/w%) could avoid interferences from/to the KMnO4 pre-oxidation and subsequent coagulation. Pilot-scale experiments confirmed the compatibility of the combined KMnO4 and PAC at existing DWTPs.

Electricity production and phosphorous recovery as struvite from synthetic wastewater using magnesium-air fuel cell electrocoagulation.

This research was based on the investigation of a major principle, regarding the effects of NaCl and KH2PO4 concentrations on struvite recovery, with electricity production using magnesium-air fuel cell electrocoagulation, in accordance with the concentration of phosphorous and chloride. The weight ratio of N:P in the synthetic wastewater was in the range of 1.2-21. The concentration of NH4Cl was fixed at 0.277 M (approximately 3888 ppm as NH3-N and 5000 ppm as NH4), while PO4-P was in the range of 0.006-0.1 M. In addition, the concentrations of NaCl as electrolyte were 0, 0.01, and 0.1 M. Phosphate removal increased linearly with the Mg:P ratio, up to approximately 1.1 mol mol-1, irrespective of the initial concentrations of phosphate and NaCl. The one-to-one reaction as mole ratio between phosphate and the dissolved Mg ions resulted in phosphate removal, with the production of a one-to-one magnesium/phosphate mineral, such as struvite. The average removal rate of phosphorous in experiments without a dose of NaCl was 4.19 mg P cm-2 h-1, which was lower than the relative values of 5.35 and 4.77 mg P cm-2 h-1, in experiments with 0.01 and 0.1 M NaCl. The dissolution rate of Mg with electro-oxidation determined the rate of phosphorous removal with struvite recovery. The average removal rates of phosphorous with dose concentrations of 0.006, 0.01 and 0.02 M KH2PO4 were 4.02, 5.54, 6.9 mg P cm-2 h-1, respectively, which increased with the increase in KH2PO4 dose. However, in experiments with a dose of 0.05 and 0.1 M KH2PO4, the average removal rates of phosphorous decreased to 4.84 and 2.51, respectively. The maximum power densities in the electrolyte mixture of 0.05 M KH2PO4/0.277 M NH4Cl, 0.01 M NaCl/0.05 M KH2PO4/0.277 M NH4Cl, and 0.1 NaCl/0.05 KH2PO4/0.277 M NH4Cl were 25.1, 26.4, and 33.2 W/m2, respectively. The increase in the NaCl dose concentration resulted in an increase in the maximum power density and current density. A dose above 0.05 M KH2PO4 resulted in the decrease of the maximum power densities. However, when the dose was below 0.05 M KH2PO4, the maximum power density increased with the increase in KH2PO4 dose.

Scaled-up dual anode/cathode microbial fuel cell stack for actual ethanolamine wastewater treatment.

The aim of this work was to develop the scale-up microbial fuel cell technology for actual ethanolamine wastewater treatment, dual anode/cathode MFC stacks connected in series to achieve any desired current, treatment capacity, and volume capacity. However, after feeding actual wastewater into the MFC, maximum power density decreased while the corresponding internal resistance increased. With continuous electricity production, a stack of eight MFCs in series achieved 96.05% of COD removal and 97.30% of ammonia removal at a flow rate of 15.98L/d (HRT 12h). The scaled-up dual anode/cathode MFC stack system in this research was demonstrated to treat actual ETA wastewater with the added benefit of harvesting electricity energy.