The TiO₂/Bi₂WO₆ composite was successfully synthesized by a simple one-step synthesis. Various analytical techniques such as scanning electron microscopy (SEM), Fourier-transform infrared (FTIR) spectroscopy, X-ray powder diffraction (XRD), diffuse reflectance spectroscopy (DRS), UV-vis spectroscopy (UV-vis) were used to determine the characteristics of the synthesized composites. The photocatalytic activity of the synthesized composite was evaluated in the degradation of the Norfloxacin (NOR) antibiotic. Under the optimal conditions, the removal rate of NOR antibiotic with the TiO₂/Bi₂WO₆ composite was more significant than that obtained with single materials. The outstanding photocatalytic activity was ascribed to the synergistic effect between TiO₂ and Bi₂WO₆, which decreased the recombination of e⁻/h⁺ pairs and enhanced the visible light absorption capacity. The investigations on radical scavengers revealed that ^•O₂⁻ and ^•OH species were primarily responsible for removing the NOR antibiotic. The potential photocatalytic mechanism was also proposed.

Aerobic granular sludge (AGS) application for wastewater treatment has been proven to have high sludge-water separation efficiency, great treatment capacity, and strong tolerance to toxic and harmful substances. Nevertheless, the AGS storage and recovery issue has only been studied in a few research. This paper studied the optimized condition for reactivation of the AGS after 3 years storage in distilled water at 4°C. The initial results revealed that under the synthetic wastewater conditions of 450 ± 0.5 mg COD/L, 65 ± 0.2 mg NH₄⁺-N/L, 15 ± 0.1 mg PO₄^3–-P/L, and the DO concentration was controlled at 20% of the saturation oxygen, it took about 30 days to gain the same volume of AGS as before storage, but not the granular size. The aeration time was susceptible to the growth of bacterial aggregates. The optimum aeration time of 172 minutes was chosen to achieve up to 11.58 g/L MLSS and 46.73 mL/g SVI30. With that reactivated AGS, substantially high organic and nutrient removal efficiencies were obtained with 97.8%, 100%, and 86.7% for COD, NH₄⁺-N, and PO₄^3--P, respectively. The future study will apply real domestic wastewater with different organic and nutrient loadings to test its stability and reproducibility in these specific culture conditions.

Greywater irrigation is becoming popular in urban farming, especially in developing countries. However, farmers’ perception of nontraditional irrigation methods is significant for their successful implementation. Therefore, this study was designed to identify the perception levels of urban farmers in the Colombo District in Sri Lanka towards greywater irrigation and to identify the factors that influence their perception levels. The results revealed that the urban farmers in the Colombo District are willing to reuse greywater for farming activities and farm management factors such as irrigation source, farm size, and farmers’ preference for different crop types have a significant influence on their perception of greywater irrigation.

Integrating power-to-gas system with anaerobic digestion is an innovative approach towards sustainable energy generation where biogas production is enhanced through the addition of clean hydrogen. However, concerns regarding its stable performance and inhibition control remain particularly in thermophilic conditions. The objective of this research is therefore to develop a feasible and energy-efficient operation of biomethanation by assessing the hydrogen dissolution rate and biogas productivity in a thermophilic anaerobic digestion system. Two digesters (2 L) were fed with sewage sludge and operated simultaneously under 55.0 ± 0.1°C. Results revealed low equilibrium hydrogen gas concentration (< 1%) in the biogas implying an effective hydrogen gas-to-liquid mass transfer at a hydrogen injection rate of 0.54 NL L-reactor⁻¹ d⁻¹. At this loading rate, high methane concentration (81 ± 1%) was observed with biogas yield up to 0.67 NL g-(volatile solids added)⁻¹. However, a sudden increase in loading resulted in a significant decrease in biogas production where possible inhibition due to high pH and volatile fatty acids accumulation had occurred. The findings from this study provide fundamental information to understand the underlying mechanism and performance of exogenous hydrogen addition in the digestion process.