Water Science and Technology最新文献

A biochar from co-pyrolysis of a mixture of sawdust and biological sludge (70/30, w/w), providing a high environmental compatibility in terms of water leachable polycyclic aromatic hydrocarbons and inorganic elements, together with a remarkable surface area (389 m²/g), was integrated into laboratory-scale vertical-flow constructed wetlands (VF-CWs), planted with Phragmites australis and unplanted. Biochar-filled VF-CWs have been tested for 8 months for the refining of effluents from the tertiary clariflocculation stage of a wastewater treatment plant operating in a mixed domestic-industrial textile context, in comparison with systems filled with gravel. VF-CW influents and effluents were monitored for chemical oxygen demand (COD), nitrogen and phosphorus cycles, and absorbance values at 254 and 420 nm, the latter as rapid and reliable screening parameters of the removal of organic micropollutants containing aromatic moieties and/or chromophores. Biochar-based systems provided a statistically significant improvement in COD (Δ = 22%) and ammonia (Δ = 35%) removal, as well as in the reduction of UV-Vis absorbance values (Δ = 32-34% and Δ = 28% for 254 and 420 nm, respectively), compared to gravel-filled microcosms. The higher removal of organic was mainly attributed to the well-known adsorption properties of biochars, while for nitrogen the biological mechanisms seem to play a predominant role.

The efficiency of Anabaena sp. was analyzed for the phytoremediation of wastewater loaded with organic matter and heavy metals like chromium. Simulated wastewater was contaminated with chromium. A side-stream membrane bioreactor was used for the treatment of wastewater. A feed tank of 20 L capacity was used with a stirring arrangement. A ceramic microfiltration membrane composed of clay and alumina was obtained from Johnson & Johnson. The removal efficiency of chemical oxygen demand, biochemical oxygen demand, and chromium was evaluated. The process was used for algae harvesting and wastewater treatment. About 92% of chemical oxygen demand (COD), 98% chromium, and oil and grease were completely removed. Membrane fouling was explained by the pore blocking and cake resistance model. Stress in algal cells was determined from the superoxide dismutase (SOD) and catalase (CAT) analysis. The lipid content of algal cells was measured.

This study aims to investigate the differences in intra-urban catchments with different characteristics through real-time wastewater monitoring. Monitoring stations were installed in three neighbourhoods of Barcelona to measure flow, total chemical oxygen demand (COD), pH, conductivity, temperature, and bisulfide (HS^-) for 1 year. Typical wastewater profiles were obtained for weekdays, weekends, and holidays in the summer and winter seasons. The results reveal differences in waking up times and evening routines, commuting behaviour during weekends and holidays, and water consumption. The pollutant profiles contribute to a better understanding of pollution generation in households and catchment activities. Flows and COD correlate well at all stations, but there are differences in conductivity and HS^- at the station level. The article concludes by discussing the operational experience of the monitoring stations.

Global water scarcity increased the demand for clean water, leading to attention on microalgae-based biological treatment for wastewater due to economic feasibility and sustainable biomass applications. This study isolated indigenous microalga Coelastrella sp. KNUA068 from a wastewater treatment plant, observed its admissible growth rate in diluted cattle wastewater (DCW), and used it for wastewater treatment analysis. The microalga showed high growth rates in indoor and outdoor cultivation with 100% DCW. In addition, the ammonia nitrogen and nitrate nitrogen removal rates of the microalga were 69.97 and 60.35%, respectively, in indoor cultivation, and 50.63 and 67.20%, respectively, in outdoor cultivation. Carotenoid content analysis revealed lutein as the highest productivity carotenoid, and zeaxanthin production was higher in outdoor cultivation. The biomass exhibited suitable biodiesel quality with a cetane number of 50.8 for high-quality biodiesel production. Coelastrella sp. KNUA068 demonstrates potential for bioenergy feedstock, carotenoid production, and wastewater treatment.

In the current study, a novel methylene blue (MB)-based colorimetric method for a quick, inexpensive, and facile approach for the determination of fouling intensity of reverse osmosis (RO) membrane has been reported. This technique is based on the interaction of MB with the organic foulants and shows the corresponding change in the colour intensity depending on the severity of fouling. The organic foulants, such as albumin, sodium alginate, and carboxymethyl cellulose (CMC), were chosen as model foulants, and the membranes were subjected to foul under extreme fouling conditions. The fouled membranes underwent an MB treatment followed by image-processing analyses. The severity of surface fouling of membranes was evaluated in terms of fouling intensity and correlated with the corresponding decline of permeate flux. The maximum fouling intensity of the albumin, sodium alginate, and CMC sodium were found to be 8.83, 23.38, and 9.19%, respectively, for the definite concentration of foulants. The physico-chemical interactions of the given foulants and MB were confirmed by changes in zeta potentials and increased sizes of the foulant by the dynamic light scattering technique. The surface fouling over the membrane surface was confirmed by the characterization of membranes.

In this study, polyoxometalates (POMs) as a core-modifying material was used to fabricate the nanofiltration (NF) membrane on the polyvinylidene fluoride (PVDF) microfiltration membrane substrate via a novel interfacial polymerization (IP) method. The formation mechanism of the POMs-modified composite membrane was proposed. The separation and antifouling properties were further investigated. After cross-linking with POMs through the new IP reaction, the modified composite membrane showed improved hydrophilicity, water flux, and salt rejection. In the humic acid fouling experiment, the POMs-modified membrane exhibited the best antifouling performance, with a flux recovery rate of up to 91.3%. Electrochemical impedance spectroscopy was further used to investigate the antifouling performance of the membranes. Nyquist and Bode plots of the POMs-modified membranes showed no significant change before and after fouling compared to the PVDF membrane substrate, indicating reduced fouling attachment on the modified membrane, which was consistent with the fouling index and flux variation observed during the fouling experiment. Our findings provide a simple and valuable route for fabricating POMs-functionalized NF membranes with desirable separation and antifouling performance.

Permeable pavements play an effective role in reducing runoff by decreasing the impermeable area. But, conventional permeable pavements suffer disadvantages such as low resistance. To address this, the 'high-strength clogging-resistant permeable pavement (CRP)' has been developed. The present study aimed to evaluate the performance of the CRP model with varying percentages of coverage (A) of 25, 50, and 100%, slopes (S) of 1, 3, and 5%, as well as rainfall intensities (I) of 45, 55, 70, 90, 170, and 200 mm/h. Based on the results, there was an increase in A from 50 to 100% at I = 90 mm/h, decreased runoff coefficient (C) of 18, 15, and 13% at S of 1, 3, and 5%, respectively. At the same I, increasing S from 1 to 5% increased the C coefficient in A of 0, 25, 50, and 100% by 3, 31, 32, and 39%, respectively. Due to the ever-increasing urbanization and the subsequent increase in impervious areas, the risk of severe floods has greatly increased. Therefore, providing solutions such as the CRP model can help reduce flood risks in urban areas. The findings of this research can be used as a guide in the design of high-strength clogging-resistant permeable pavements in urban areas.