Photoelectrocatalytic treatment of municipal wastewater with emerging concern pollutants using modified multi-layer catalytic anode.

Municipal wastewater contains emergent chemical and biological pollutants that are resistant to conventional wastewater treatments. Therefore, the focus of the current study was to address the challenge of removing emergent chemical and biological pollutants present in municipal wastewater. To achieve this, a photo electro-catalytic (PEC) treatment approach was employed, focusing on the removal of both micro and biological pollutants that are of emergent concern, as well as the reduction of Chemical Oxidation Demand (COD) and Total Organic Carbon (TOC). The treatment involved the use of a modified multi-layer catalytic anode photo-electroactive anode as an effective anode for PEC treatment of municipal wastewater. In the continuous mode of operation, %COD removal was optimized for the treatment of municipal wastewater under Ultra-Violet C (UVc), 280 nm, and Visible (Vis) radiation, 400 nm. Therefore, a comparative study was performed to investigate the effect of Vis radiation on %COD removal, micropollutants removal, and disinfection of municipal wastewater. Micropollutants present in municipal wastewater were effectively oxidized/degraded with the highest reduction rate between 100% and 80% under the influence of UVc and Vis radiation respectively by the PEC treatment process. Disinfection of various microorganisms present in the wastewater with the effect of UVc and Vis assisted PEC treatment was also monitored. Overall, 75-80% of the disinfection of municipal wastewater was contributed by the modified multi-layer catalytic anode. The UVc in the PEC system, contributes approximately 20-25% to the overall disinfection of municipal wastewater.

Modified bio-electrocoagulation system to treat the municipal wastewater for irrigation purposes.

A modified biological-integrated electrocoagulation method was explored to treat municipal wastewater (MWW) for irrigation purposes. To use treated wastewater for irrigation purposes a wide range of contaminants removal was focused on in this study (turbidity, hardness, conductivity, TDS, TSS, chloride, Ammonia nitrogen, BOD, COD, and total coliform). Raw municipal wastewater (RMWW) was treated in a modified Bio-Electrocoagulation (BEC) cell. The cell was operated in a continuous flow mode and consisted of an electrocoagulation stage using aluminum (Al) electrodes followed by a bioremediation stage using a fixed bio-filter (BF), the design of the cell was further modified by the addition of a sand filter (SF). The effect of several parameters such as applied voltage (22, 26, and 30 V), inlet flow rate (1, 3, and 5 Lh-1), and initial pH (pH 3, 5, 7, 7.4, and 9) was investigated to determine the optimum operating conditions for selected responses. The most effective operating conditions for the BEC were investigated for the different irrigation water quality (WQ) indicators. It was observed that pH 7.4 and 26 V provide maximum removal efficiency of contaminants at the flow rate of 1 Lh-1. A fixed film BF plays a positive role to improve the degradation of contaminants after the EC unit up to 4% of NH3-N, 9.3% of BOD, and 7.8% of COD. In addition, using the SF improved the turbidity removal to 42.6%. The WQ specifications of the treated MWW using the BEC cell were compared with the standard specifications for restricted and unrestricted agricultural irrigation water. The overall operating cost of MWW treatment for irrigation purposes by using a modified bio-integrated electrocoagulation method was 0.76 $m-3.

Water footprint: applying the water footprint assessment method to Australian agriculture.

BACKGROUND: Water footprint assessment is essential for the evaluation of water scarcity that considers both direct and indirect water consumption along the supply chain. This paper presents the estimation of water footprint for locally grown fruits and vegetables in Australia. Water footprint was calculated based on the framework developed in the Water Footprint Assessment Manual for the crops which are the most practicable to grow in Australia. Nine different crops (apples, grapes, tomatoes, oranges, peaches/nectarines, cherries, potatoes, carrots/turnips and almonds) in the agricultural industry were selected and identified as the most water-consumptive crop and least water-consumptive crop. For each type of crop, the three main water footprint components (blue, green, and grey water) were calculated. RESULTS: It was found that almond had the highest water footprint (6671.96 m3  ton-1 ) and tomato had the lowest water footprint (212.24 m3  ton-1 ) in Australia. From the global comparison, it is revealed that total water footprint for Australian crops is much higher than the corresponding international average values, except for tomatoes, potatoes and almonds. Also, almonds had the highest water footprint among the nine crops investigated. CONCLUSION: The study provides an insight into future sustainable cropping patterns in Australia, which suggest that tomatoes, carrots/turnips, potatoes and apples should continue to be grown in Australia, whereas stone fruit (e.g., almonds) should no longer be grown because of its high water footprint. © 2020 Society of Chemical Industry.