ABSTRACT Many studies have investigated the nonradical pathway of rhodamine B (RB) degradation by activated persulfate (PS). However, PS can also react with RB by direct oxidation, without activation. In this study, the kinetic and mechanistic investigation of this pathway was conducted by examining the effects of the initial PS concentration, ethanol addition, and temperature. The direct reaction between PS and RB exhibited a second-order rate constant of 0.037 M−1 s−1 at temperatures ranging from 9 to 25 °C. At elevated temperatures, the sulfate radicals (SRs) produced by the dissociation of PS react with RB and compete with direct oxidation. The reaction between SR and RB had second-order rate constants of 5.0 × 106, 1.7 × 107, 3.5 × 107, and 7.81 × 107 M−1 s−1 at 25, 40, 50, and 60 °C, respectively. A comparative study was conducted to evaluate these rate constants against those reported in the literature. A reaction scheme for the direct oxidation of RB by PS is finally proposed based on data obtained from UV-Vis and HPLC-MS2 methods.

ABSTRACT Designing a biosorbent material with highly efficient adsorbent ability and cost-effectiveness is challenging. Conventional biosorbent materials have inherent drawbacks, including high cost, small porosity, less thermal stability, and low effective surface area. Herein, we employed a pyrolysis method at 600 °C to synthesize biochar derived from mango seed kernel (MSK) as an alternative biosorbent material to circumvent these shortcomings. The obtained results evidently indicate the adsorption capacity (qmax) from the Langmuir fit (R2 = 0.995) using nonlinear regression came out to be 67.56 mg/g. Two hours of contact time was required to establish equilibrium, and pH seems to have little effect on adsorption. The calculated surface area by the adsorption process was found to be 85.19 m2/g for MSK-600 revealing the intriguing surface morphology of MSK-600 in the adsorption of methylene blue and findings of our work were then compared with the activated carbon (charcoal) by determining the surface area and adsorption capacity. Our findings imply the potential for effective alternative application of MSK for (bio)sorbent development.

ABSTRACT Currently, climate change is one of the major challenges facing the global population. Rainfall variability and its unpredictable trends pose significant challenges to water resource management and agricultural productivity in western Amhara, Ethiopia. This study investigated the spatial distribution and temporal trends of rainfall using time-series rainfall data from the Enhancing National Climate Services (ENACTS) from 1991 to 2020. Rainfall variability was assessed using the coefficient of variation, precipitation concentration index (PCI), and standardized anomaly index (SAI). Mann-Kendall and Sen's slope estimator tests were also employed for rainfall trend analysis. The results show that high annual rainfall occurred during the Kiremt (wet) season, and high rainfall variability occurred during the Bega (dry) season in all rainfall grid points over the study area. SAI also witnessed the presence of inter-annual variability of rainfall with negative and positive anomalies in 46.7 and 53.3% of the reference years, respectively. Trend analysis results showed an overall non-significant increasing trend in the annual and seasonal rainfall (except Bega) during the study period. Hence, this study provides information about the spatial distribution of rainfall at different timescales, and it is crucial for water resource planners and design professionals in urban drainage, bridges, dams, and agricultural sectors.

ABSTRACT A sufficient water supply is important for human health; however, it results in the generation of large amounts of domestic wastewater. This study aimed to determine the impact of domestic wastewater on the surrounding environment as well as residents' opinions on the issue. Domestic wastewater consists of blackwater (toilet wastewater) and greywater (miscellaneous domestic wastewater), each of which is discharged in different ways. Blackwater was treated using a septic tank, without the required desludging, despite policy goals, owing to a lack of awareness among residents as well as structural problems. However, the targeted septic tanks efficiently removed microbiological indicators. It is assumed that the larger capacity and tropical savanna climate, with consistently high temperatures, were beneficial for the treatment process. Greywater was discharged into public waters without any treatment and caused degradation of the waterside environment. More than 70% of respondents thought there was a problem with the canal that flows close to houses; however, there was variation in the awareness. It is necessary to reduce the greywater load from each household at the source as much as possible, and this goal requires residents to have an accurate understanding of greywater emissions.

ABSTRACT Optimization techniques can be employed to determine the best cropping patterns to ensure optimum net benefits, food production, and labor employment. Therefore, the current investigation employed the linear programming module in LINGO 14.0 software to develop optimal crop area allocation plans in the Right Main Canal (RMC) of the Bhimsagar irrigation project. The optimal cropping patterns (OCPs) were generated for 2013–2014 under different canal run (CR) periods in a month, i.e., 30, 24, and 21 days using three objective functions, viz., net benefit, food production, and labor-days maximization. In addition, the OCP scenarios were generated for long-term agriculture sustainability scenarios, viz., 2015, 2020, and 2025. Results revealed that the net benefit was increased by 122.2, 93.4, and 95.5% for Ratanpura (RT), Chaplada (CP), and Maraita II (MT) minor, respectively, under OCP estimated for 30-day CR in 2013–2014, whereas food production was increased by 22.4, 33.8, and 25.9% for RT, CP, and MT, respectively, under OCP over existing cropping patterns. Similarly, under OCP, labor employment had increased by 40.9, 33.8, and 33.1% for RT, CP, and MT, respectively, for 30-day CR. These findings infer that higher net benefits, food production, and labor employment may be achieved by shifting to OCPs.

ABSTRACT The aquatic microbial communities are relatively complex with a high level of prokaryotic diversities. Standard and novel microbiological, analytical, and statistical techniques were employed in the collection, analysis, and comprehensive study of the samples. From the study, the mean values of total heterotrophic bacteria were determined to be 1.35 ± 0.18 (×107), 1.59 ± 0.64 (×107), and 1.56 ± 0.52 (×107) for upstream, midstream, and downstream, respectively, while the mean values for crude oil-utilizing bacteria were 1.08 ± 0.12 (×106), 1.28 ± 0.58 (×106), and 1.24 ± 0.44 (×106) for upstream, midstream, and downstream, respectively. The mean concentrations of physicochemical parameters and heavy metals obtained in the benthic sediment were significantly higher than the mean concentrations in the water samples (tidal and intertidal) (p < 0.02). The result of the component analysis of total petroleum hydrocarbons (including polycyclic aromatic hydrocarbon and benzene, toluene, ethylbenzene, and xylene) revealed significantly higher levels in the sediment than tidal and intertidal water. Structural metagenomics revealed seven top phyla, namely, Proteobacteria, Actinobacteria, Firmicutes, Bacteroidetes, Planctomycetes, Fusobacteria, and Chloroflexi. The significantly (p < 0.05) high levels of hydrocarbon-utilizing microorganisms in Iko River estuary can be taken as a sensitive index of environmental exposure to hydrocarbon pollutants in the estuary. This research revealed the response patterns of microorganisms to natural and anthropogenic gradients toward sustainability in Iko River estuary.

ABSTRACT This research explored the use of the fertigation technique with treated agro-industrial wastewater to enhance the growth of Capsicum annuum (var. Astra) and Lycopersicon esculentum (var. Kristina). The wastewater, collected from Bajwa Agro Industries in Lahore, was biotreated using the bacterial strain Bacillus paramycoides MT477810, with a 10% inoculum incubated at 37 °C for 48 h. The bacterial strain achieved an 87% decolorization of the wastewater. Physicochemical analysis before and after biotreatment showed reductions in pH (60%), EC (22%), salinity (16%), turbidity (48%), COD (40%), BOD (73%), TDS (62%), and TSS (25%). The two vegetable varieties were fertigated with both biotreated and untreated wastewater to assess their effects on seed germination and plant growth. Results indicated a significant reduction in phytotoxicity (over 50%) in plants grown with biotreated wastewater. Additionally, plants irrigated with biotreated wastewater showed a 9–30% increase in fresh and dry weights compared to those irrigated with untreated wastewater. Nutritional analysis revealed that crops irrigated with treated wastewater had 12–48% higher nutrient content. These findings emphasize the effectiveness of biological wastewater treatment and fertigation in reducing pollutants and enhancing nutrient availability for vegetable crops.

ABSTRACT With the objective of reducing its CO2 footprint and moving towards circularity by recovering influent phosphorus, Hias wastewater treatment plant (WWTP) has developed a novel biological removal process (the Hias Process) which combines enhanced biological phosphorus removal (EBPR) and moving bed biofilm reactor and is now operating at full scale. Additionally, a struvite reactor is installed to capture phosphorus from the resulting sludge. In this work, the performance of the WWTP and particularly the biological phosphorus removal process and struvite reactor is assessed with regards to circularity and recovery of phosphorus. The Hias Process demonstrates stability and effectiveness even in cold climates and during stormwater events. Introducing the Hias Process reduced the use of precipitation chemicals, leading to a lower carbon footprint. The combination of the Hias Process with subsequent struvite reactor contributes to increased phosphorus circularity. That is achieved through improved plant availability of phosphorus in biosolids and the production of struvite. Main factors affecting recovery of phosphorus are identified and include the use of precipitation metals, bypass of the EBPR, and temperature's impact on PO4 release from EBPR sludge. This study aligns with Sustainable Development Goals and emphasizes efficient phosphorus recovery through the Hias Process and struvite reactor.

ABSTRACT Water is vital for human life, socioeconomic development, and environmental conservation. Access to safe drinking water and sanitation is a human right recognized by the United Nations’ 2030 Agenda in its Sustainable Development Goal No. 6. In this context, fluoride in groundwater at concentrations of 0.6–0.9 mg L−1 is essential for dental health. However, at higher levels (>1.5 mg L−1), it is harmful to health. Thus, this study evaluated the removal of excess fluoride from groundwater in defluoridation systems installed in rural schools using activated bone charcoal as an adsorbent. The performance results of the campus defluoridation system indicate that the system can meet the consumption needs of a school with up to 39 people consuming 2 L day−1, with a minimum flow rate of 3.3 L h−1, for a minimum period of 90 days. Regarding the efficiency of fluoride removal from water in rural schools A, B, and C, the results indicated a value higher than 97%, meeting potability standards. The technology is sustainable, improves sanitation conditions, and ensures safe and accessible drinking water for all.