Sustainable Technologies for Water Purification

Zinc oxide (ZnO) is a vital semiconductor that is widely used for a wide variety of purposes. It is known that this material has a wide bandgap, and this property makes it sensitive to UV radiation. This way, ZnO nanoparticles can be used as photocatalysts in various processes and exhibit excellent catalytic activity. This study aims to produce a new and effective catalyst by combining ZnO nanoparticles used as photocatalysts with MXene, a two-dimensional material. MXenes have a great potential in terms of environmental sustainability. MXenes offer a wide range of sustainable solutions, from energy storage to water treatment, carbon capture to environmentally friendly electronics. The studies carried out for this purpose were carried out in two stages. In the first part, the composite particle was synthesized. In the second part, the produced composite was used as a photocatalyst in the photocatalytic degradation of tetracycline, an endocrine disruptor commonly encountered in wastewater. Optimum conditions were determined for operational parameters such as catalyst dosage, pollutant concentration, pH, irradiation time, light intensity, and temperature, which have the potential to affect the process efficiency significantly. The experiments conducted under optimum conditions determined that the organic pollutant in the solution was removed entirely. Full article

This work develops a comprehensive review of the main conventional and emerging desalination processes. It presents the state of knowledge of the most known and investigated techniques, highlights their advantages and drawbacks, and draws appropriate conclusions on their respective performances from various angles including their energy consumption and efficiency, environmental impacts, reliability, and flexibility in operations. This review reveals the recent large dominance and deployment of the reverse osmosis technology in the Gulf countries, mainly in Saudi Arabia; the importance of hybridization; and the slow penetration of promising processes including membrane distillation and forward osmosis into the industrial desalination market. In addition, this work aims to develop some comparison exercises between these processes using specific criteria. A cross approach allowing an easier comparison between various desalination processes could help identify the advantages and drawbacks of each technology and select the appropriate process. Therefore, various criteria allowing a clear picture to be drawn of the performance and capabilities of the main conventional and emerging desalination processes have been proposed in the frame of sustainable development. As an illustration of this general approach from sustainability prospects and considering specific weights for each proposed criterion for the case of Saudi Arabia, a comparison exercise reveals that the superiority of reverse osmosis (RO) is confirmed. Multiple effect distillation (MED) and membrane distillation (MD) processes are potentially competitive to RO while multi-stage flash (MSF) comes last due to several drawbacks. Full article

Increasing urbanisation is occurring in Australia’s major cities and in almost every country in the world. This creates a challenge for the urban water sector, which not only needs to provide traditional water services (i.e., wastewater, domestic water) for a rapidly growing population, but also to service potential additional demands to contribute to enhanced amenity, and to do so in the context of climate change. This paper is focused on stormwater management controls for the develop of new greenfield urban sites in the three major east coast Australian cities—Melbourne, Sydney and Brisbane. While stormwater management in all three cities is focused on the protection of community values of the waterways, including environment (ecology), amenity and recreation, the scale or type of the waterways considered is considerably different—Melbourne has adopted a regional waterway strategy, while the Sydney and Brisbane approach is more localised. Pollution load reduction targets (TSS, TP, TN and litter) from new urban areas have been enforced in all three cities for many years, although there is concern that these targets primarily aimed at protecting the values of downstream bays (e.g., Port Phillip Bay, Sydney Harbour and Morton Bay) will not necessarily protect the values of the contributing waterways. However, targets to control stormwater volumes entering waterways are proving to be considerably more difficult to both develop and implement. These targets are typically expressed as volumes of stormwater to be harvested and/or infiltrated for every additional hectare of directly connected impervious (DCI) surface created as a result of urban development. The three cities have approached the setting of stormwater flow targets somewhat differently, as is apparent from the details provided in the paper. Additionally, we argue that there is a need for the development of new targets related to the reuse of stormwater and its integration with wastewater and domestic water management. Full article

Ball milling, as a cost-effective and eco-friendly approach, has been popular in materials synthesis to solve problems involving toxic reagents, high temperatures, or high pressure, which has the potential for large-scale production. However, there are few reviews specifically concentrating on the latest progress in materials characteristics before and after ball milling as well as the adsorptive application for aqueous pollutants. Hence, this paper summarized the principle and classification of ball milling and reviewed the advances of mechanochemical materials in categories as well as their adsorption performance of organic and inorganic pollutants. Ball milling has the capacity to change materials’ crystal structure, specific surface areas, pore volumes, and particle sizes and even promote grafting reactions to obtain functional groups to surfaces. This improved the adsorption amount, changed the equilibrium time, and strengthened the adsorption force for contaminants. Most studies showed that the Langmuir model and pseudo-second-order model fitted experimental data well. The regeneration methods include ball milling and thermal and solvent methods. The potential future developments in this field were also proposed. This work tries to review the latest advances in ball-milled materials and their application for pollutant adsorption and provides a comprehensive understanding of the physicochemical properties of materials before and after ball milling, as well as their effects on pollutants’ adsorption behavior. This is conducive to laying a foundation for further research on water decontamination by ball-milled materials. Full article

Industrial wastewater typically contains many organic and inorganic pollutants and is also contaminated by various microorganisms. Microbial species in industrial wastewater have not been extensively investigated. In this experiment, a Klebsiella pneumoniae strain was isolated for the first time from industrial wastewater containing a high concentration of sulfate and phosphate. Mass spectrometry, genetic analysis, and biochemical identification were conducted to understand the genetic and biochemical characteristics of this Klebsiella pneumoniae strain recovered from industrial wastewater. Growth experiments revealed that it exhibited an excellent growth rate in nutrient broth. Further analyses showed that the strain was sensitive to most antibiotics but resistant to chloramphenicol and nitrofurantoin. It also exhibited significant resistance to piperacillin/tazobactam and cefotaxime/clavulanic acid. Resistance gene experiments indicated the presence of gyrA, OqxB, and ParC genes associated with antibiotic resistance in the isolated Klebsiella pneumoniae strain. Proteomics uncovered the following three proteins related to drug resistance: the multi-drug resistant outer membrane protein MdtQ, the multi-drug resistant secretion protein, and the modulator of drug activity B, which are coexistent in Klebsiella pneumoniae. Proteomics and bioinformatics analyses further analyzed the protein composition and functional enrichment of Klebsiella pneumoniae. The isolation of Klebsiella pneumoniae from a high concentration in sulfate and phosphate industrial wastewater provides a new direction for further research on the characteristics and drug resistance traits of industrial wastewater microorganisms and the potential risks they may pose when released into the environment. Full article

The pollutant content in initial rainwater is very high, so the treatment and research of initial rainwater has become an engagement issue in controlling non-point source pollution and realizing sustainable development in Chinese cities. This study explores the best flow pattern suitable for treating initial rainwater by electrocoagulation (EC), and a pilot-scale experiment is conducted to analyze the effect of the EC process on the treatment of initial rainwater. The findings indicate that the latter enhances the turbulent flow effect and the EC process treatment effect better under the two flow modes of parallel perforation flow and dislocation perforation flow. For the dislocation perforated flow pattern, the removal rates of suspended matter (SS), chemical oxygen demand (COD), and phosphorus (TP) are 94.00%, 81.95%, and 98.97%, respectively, which reach the expected treatment targets. Using the electrocoagulation–filtration (ECF) process to treat initial rainwater, the final effluent exhibits high quality and could be used as urban circulating cooling water. Specifically, SS, COD, and TP concentrations are 15.00 mg/L, 21.06 mg/L, and 0.11 mg/L, respectively. The hydraulic retention time of the process is short, only 30 min, and the energy consumption is low, 0.57 kWh. This study provides a reference for the sustainable treatment of early urban rainwater and the design of the flow pattern of the EC process. Full article