A new adsorbent modified from orange peel (OP) was successfully synthesized by ethylenediamine crosslinking method to remove Cr(VI) from wastewater. The modified orange peel powder (MOPP) was investigated in a batch adsorption system, including both equilibrium adsorption isotherms and kinetics. Effects of several factors, including adsorbent dose, initial pH and Cr(VI) concentration were studied. The data indicated that the pH was not an essential factor that affected the adsorption process, it has a wide pH range from 4 to 10, and high adsorbent dose and lower Cr(VI) concentration could increase the Cr(VI) removal efficiency. Equilibrium data were analysed using the Langmuir, Freundlich and Temkin isotherm models and found to be well represented by the Langmuir isotherm model. The maximum capacity (qmax) obtained from Langmuir model was 52.08 mg/g at pH 6.0. The kinetics of adsorption followed the pseudo-second-order kinetic equation. The results suggest that MOPP is an inexpensive and efficient adsorbent for removing Cr(VI) from aqueous solution.

In this study, the applicability of electrocoagulation using iron electrodes in real dyeing wastewater treatment was assessed based on pollutants removal efficiency, sludge generation, energy consumption and operation cost in practice. The effects of current density, pH, conductivity, and reaction time on treatment performance were evaluated. The operation cost of electrocoagulation was calculated including the energy cost, the iron plate cost, generated sludge treatment cost, and added substances cost. The results indicated that the colour, CODcr and TSS removal efficiencies were high and quite stable with short reaction time (reached 92.07 ± 1.21%, 65.7 ± 1.47%, and 89.8 ± 1.2%, respectively, with only 15 min). Average sludge generation, specific energy consumption, and operation cost were determined respectively as 0.645±0.0543 kg/m3, 1.182 kWh/m3 and 0.517 USD/m3. Coagulation-flocculation using FeSO4 was performed as a control experiment as well. Compared to coagulation-flocculation, electrocoagulation has the same removal efficiency but has less generated sludge (only 50%) and little to no added chemicals. Therefore, the operating cost was quite less than the others, with only 0.517 USD/m3 instead of 1.99 USD/m3 (equal to 1/3.5).

Microbial fuel cells (MFC) have gained focus due to their diversity in operating conditions & substrates for the generation of sustainable green energy. In the present study, novel MFC has been fabricated using the recyclable aluminum can as air-cathode and graphite rod as anode for the treatment of domestic wastewater and simultaneous power generation. Three different substrate (COD) concentrations, high (>800 mg.L-1), medium (250 mg.L-1 - 800 mg.L-1) and low (<250 mg.L-1) were used. The maximum COD removal efficiencies, voltage generation, power densities were found to be 80%, 0.71 V, and 304.46 mW.m-2 respectively in high strength wastewater setup. In both medium and low strength wastewater setups, after 288 hours, the COD was reduced below 50 mg.L-1 thus limiting the electricity generation substantially. Setup with low-strength wastewater produced a maximum CE (%) of 13.80. Overall results showed that although high-strength wastewater produced better and maximum power densities, medium and low-strength wastewater setups were more consistent in energy generation throughout the experiment.

Dairy industry contributes to the pollution of the environment, both in quality and quantity. It generates about 0.2 to 10 L of effluent per liter of milk processed. Up-flow anaerobic sludge blanket is most suitable for biodegradable wastes, hence the present study evaluated the performance of UASBR through a laboratory model (25 liters of volume) for treating the dairy effluent with maintained psychrophilic temperature (15-20ºC) at phase I and mesophilic temperature (30-40ºC) at phase II. This model was studied for its treatment efficiency in terms of COD reduction. In the phase I, the average varying influent COD applied over the model are 1684, 2693, 3160, 3637, and 4059 mg/L with flow rates for each average influent COD as 4.80, 9.60, 14.40, 19.20 and 24.00 L/d. It was found that, successful COD removal of 91.42% was for the operating conditions of OLR at 0.039 kg COD/kg VSS day, VLR at 0.70 kg COD/m3 day and HRT at 5.21 days. In the phase II the average varying influent COD of 2316, 2827, 3329, 3908 and 4522 mg/L were applied with same flow rates. The experimental work on UASBR model was found successful with 94.70% COD removal under the operating conditions of OLR at 0.037 kg COD/kg VSS day, VLR at 0.630 kg COD/m3day and HRT at 5.21 days. The reactor achieved BOD, TSS, TDS, N and P removal efficiency, observed in phase I and II, as 91%, 82%, 89%, 42% and 46% and 96.4%, 86%, 91%, 41% and 50% respectively.

Unavoidably, the expansion of industry causes the release of numerous heavy metals, radionuclides, and organic pollutants into the environment. Due to these pollutants, the extremely toxic, highly carcinogenic chemicals provide a serious risk to people and aquatic life. Wastewater pollutants must be removed to safeguard the ecology. A huge specific surface area, multiple binding sites, a plethora of functional groups, variable pore size, and simplicity of surface modification are just a few advantages of porous materials. They are considered viable candidate materials for the efficient and selective removal of contaminants from aqueous solutions in a range of difficult circumstances due to their benefits. This work reviews the characteristics, methods of functionalization, and ways of modification of many novel porous materials in recent years. The use of these porous materials in the treatment of wastewater was examined. The development potential of porous materials is finally summed up.

This study was conducted to assess the optimization of the coagulation-flocculation process and to investigate the interactive effects of experimental factors in automotive wastewater treatment. Based on the coagulation-flocculation process, an automotive wastewater was treated using polyaluminium chloride as the coagulant and anionic polyacrylamide as the flocculant. Response surface methodology was applied to optimize the operating variables: coagulant dosage, flocculant dosage and pH. We found that the optimum conditions for chemical oxygen demand removal (73.7%) were, a coagulant dosage of 73.3 mg/L, a flocculant dosage of 3.46 mg/L and pH 7.45. The optimum conditions for the removal of heavy metals (Fe, Cr, Cu) were, a coagulant dosage range of 65.26-170.9 mg/L, a flocculant dosage of 5.36 mg/L, and pH 6.13 (with 78.7-99.7% of heavy metals removal). The experimental data and predicted model proved that RSM is a suitable approach for optimizing the coagulation-flocculation process in automotive wastewater treatment.

Microbial fuel cell is regarded as a new wastewater treatment technology, which has the advantages of high-efficiency, low energy consumption, clean and environmental protection. As a complex biological electrochemical reaction system, many factors will have significant impacts on its performance. Solving the bottleneck problem of microbial fuel cell, operation is the key precondition to promote its practical application. This paper studies the effect of electrolyte and electrode area on the microbial fuel cell for wastewater treatment through experiments, so as to provide the basis for applying microbial fuel cells into an actual wastewater treatment system. The experimental results show that using microbial fuel cells for restaurant wastewater treatment, we can achieve water purification effect in certain, and electrolyte and electrode area are important factors affecting the wastewater treatment performance. By choosing a suitable cathode electrolyte, the sewage treatment performance of the microbial fuel cell can be improved effectively.

In the present article, a perspective method of biological sorption process of wastewater treatment in the chemical industry is reviewed. This article focuses on the carbonate sludge produced by heat power stations that is used as a sorption material, and adsorption properties of carbonate sludge and its influence on activated sludge are considered. Sludge is a micro and mesoporous sorbent, which is confirmed by the sorption curves for formaldehyde and ammonia nitrogen. Removal of ammonia nitrogen and reduction of COD and BOD5 in aqueous solutions by means of carbonate sludge was investigated. It was observed that the maximum removal of COD, BOD5 and ammonium nitrogen was achieved at 600 mg/L dosage adsorbent carbonate sludge. This dose helped to reduce COD in water by 91% on the average, BOD5 by 98% and ammonium nitrogen by 94%. It was found that the biological sorption process is more effective than biological wastewater treatment. A modified biological wastewater treatment line was submitted to the Kazan Synthetic Rubber Plant (Russia).