ABSTRACT In this study, a water quality analysis was conducted at 24 surface water monitoring stations for 17 water quality parameters to investigate the spatial variability of the constituents, determine the possible sources of pollution and quantify the contribution of each identified source on individual parameters using multivariate statistical analysis (MSA) and the multivariate receptor model (MRM) conjunctively. Although most of the analysed water quality constituents were in the recommended water quality guideline standard, nutrient concentration at some of the monitoring stations was found above the permissible limit, making the water resources in the river basin prone to eutrophication and leaving the aquatic life completely at risk. On the other hand, based on factor analysis in the basin (which explained 86.9% of the total variance with four principal factors), agricultural (nutrient) waste is the dominant pollution source followed by ground water intrusion and mineral dissolution. Besides, the MRM analysis using the UNMIX model-assigned source contribution to individual parameters with a minimum signal-to-noise ratio (S/N) of 3.38 > 2 and R2 of 0.88 > 0.8. A coordinated land use management and continuous water quality monitoring could be a better approach to managing the increasing pollution level in the catchment.

ABSTRACT The contamination of wastewater with pharmaceutical compounds represents a growing environmental challenge due to the inefficiency of conventional treatment systems in removing these emerging contaminants. The coffee husk (CH) is a promising bioadsorbent due to its abundant availability as a byproduct of coffee production. This study focuses on using untreated CH as an adsorbent for removing acetaminophen (ACE) and ciprofloxacin (CIP) while exploring the impact of pyrolysis temperature on the adsorption efficiency of these pharmaceutical compounds. The results reveal an excellent CH performance in removing CIP, achieving 64% removal with a maximum adsorption capacity of 37.00 mg/g. Increasing the pyrolysis temperature during the heat treatment of coffee husks significantly affects the adsorption of CIP. This behavior is primarily due to the reduction in functional groups, which are essential for facilitating the adsorption of CIP onto the resulting biochar. Thermodynamic parameters (ΔH° > 0 and ΔG° > 0) indicate that CIP adsorption on CH is an endothermic and not spontaneous process. The removal efficiency of CIP on CH for synthetic wastewater and urine matrices showed that CH can effectively remove CIP from wastewater. Finally, the reuse of CH as a bioadsorbent highlights its potential to contribute to water quality improvement and environmental preservation.

Abstract The study attempted to assess the water quality around the tannery effluent discharge areas for suitability for irrigation purposes using different indices (Water Quality Index (WQI)) and statistical analysis in Savar Upazilas, Dhaka, Bangladesh. The samples were collected three times, from monsoon 2021 to pre-monsoon 2023. The analysis results showed that the concentrations of various parameters at most of the sampling points exceeded the surface water standard. Pollution levels were found in the following order: pre-monsoon, post-monsoon, and monsoon. At SW1 point, the CWQI, WWQI, and MWQI of the surface water quality showed a ‘poor’ category. The IWQI values showed that the surface water at all the sampling points was suitable for irrigation purposes, except for the SW1 sampling point. The NPI indicates that EC, BOD, COD, TSS, Cl−, Na+, and NO3--N parameters were potentially responsible for polluting most sampling sites. Multivariate statistical analyses like principal component analysis, cluster analysis, and Pearson correlation matrix showed significant anthropogenic intrusions of these variables in surface water in the area. A strong correlation between these parameters indicated their common origin, i.e., poorly treated tannery industry effluent entered the surface water, suggesting an improvement in the efficiency of the Central Effluent Treatment Plant (CETP).

Abstract Certain plants have been identified with the capability to take up metallic and metal oxide nanoparticles (ENPs), thus suggesting their potential role in phytoremediation. The reported study evaluated the response of two aquatic plants, sedge (Carex rostrata) and cattail (Typha latifolia), on their exposure to Ag, ZnO, TiO2, BiVO4/Pd, and Cu2O/Pd nanoparticles over 15 weeks. Plant physiological responses (chlorophyll content, carbonic anhydrase (CA) activity, leaf area, production of new shoots, and root length) varied according to the plant species and ENP type. By week 15, sedge treated with BiVO4/Pd ENP had a high chlorophyll content and increased CA activity and leaf area compared to the control. In contrast, cattail had reduced chlorophyll levels and number of new shoots when exposed to exogenously applied BiVO4/Pd. Highest sedge chlorophyll content at week 15 was measured in the mixed-ENPs, Cu2O, and Ag (53.2, 35.8, and 32.7%, respectively, greater than the control). The ZnO ENPs were beneficial for sedge chlorophyll content, cattail shoot production and root length. The mixed-ENPs treatment imparted positive effects to several sedge properties (CA and new shoots) and cattail (chlorophyll, leaf area, and root length). Additional research is needed to assess the capabilities of different aquatic plant species to tolerate metal-based ENPs for remediation purposes.

Abstract This study was conducted to simulate the sediment yield and evaluate best management practices (BMPs) for sediment control in the Azuari watershed, Upper Blue Nile basin, Ethiopia using the Soil and Water Assessment Tool (SWAT) model. As inputs for the model, 30 years (1991–2020) of daily values of meteorological data were used. For model simulation, daily stream flow and sediment data were collected for the periods from 1988 to 2012. The study area was delineated into 19 subwatersheds and the sediment yield was estimated in each subwatershed using the modified universal soil loss equation. The average simulated sediment yield in the watershed was found to be 10.81 t/ha/yr. Six subwatersheds were identified to have high to severe sediment yields and are considered hotspot areas which require prior mitigation measures to control sediment. Four soil and conservation measures were evaluated in SWAT as BMPs namely filter strip, terracing, strip cropping, and contouring. Filter strip was found to reduce sediment by 35.61%, terracing by 20.44%, strip cropping by 44.12%, and contouring by 43.6%. Thus, the implementation of strip cropping resulted in maximum sediment yield reduction. The findings of the study would help to make informed decisions on best watershed management strategies.

Abstract Septic tank systems (STSs) are widely utilised flowsheets for decentralised wastewater treatment in the UK. With a growing consensus that STSs have a sizeable detrimental impact on the environment, there is a need for rural flowsheets with improved treatment capabilities. This study examines the lifetime cost and carbon emissions of using an enhanced septic tank nature-based solution (EST-NBS) to improve STS compared to a package treatment system (submerged aerated filter (SAF)). The wholelife cost (WLC) of the flowsheets and Scope 2 cradle-to-grave lifetime carbon emissions (LCEs) of the flowsheets were assessed. The EST-NBS flowsheets represent a lower cost improved treatment system than SAFs at population equivalents (PEs) from 5 to 1,000. An STS averages an LCE of over 4,000 kg CO2eq PE−1, with all other considered flowsheets having lower emissions. The EST-NBS flowsheets had lower carbon emissions than SAFs. Even at low populations upgrading from an STS to an EST-NBS is a competitive abatement strategy, with costs of £260 tCO2eq−1 emissions avoided, at 1,000 PE an NBS flowsheet has an abatement cost of –£17 tCO2eq−1. This shows the potential of using NBS flowsheets in rural wastewater treatment providing both a carbon and cost incentive against traditional designs.

Abstract The dynamics of trophic status estimation of case-2 water bodies on a synoptic mode for frequent intervals is essential for water quality management. The present study attempts to develop trophic status estimation approaches utilizing Landsat-8 and Sentinel-2 images as inputs. The chlorophyll-a concentration, a proxy parameter for trophic status, was estimated using the empirical method, fluorescence line height (FLH) method, and artificial neural network (ANN) approaches using spectral reflectance values as inputs. The outcomes following the empirical approaches revealed the scope of kernel normalized difference vegetation index (kNDVI) (R2 = 0.85; RMSE = 2 μg/l) for estimating the chlorophyll-a concentration using Sentinel-2 images of the Godavari River basin. Though the performance of the FLH method (R2 = 0.91; RMSE = 1.6 μg/l) was superior to kNDVI-based estimation, it lacks the capability to estimate chlorophyll-a concentration above 20 μg/l. Due to the existence of eutrophic regions within the Godavari basin (28%), adopting better approaches like ANN for trophic status estimation is essential. To accomplish the same, the Levenberg–Marquardt algorithm-based ANN was developed using non-redundant bands of Sentinel-2 as inputs, and Sentinel-3 derived chlorophyll-a values as output. The developed architecture was successful in estimating trophic status estimations at all levels.

Abstract This study determined the water quality of the three major domestic water sources of Bontoc, Mountain Province, and recommended interventions to maintain water parameters within values set by the Philippine National Standards for Drinking Water (PNSDW). Results revealed that all the average values of the physico-chemical parameters measured during wet and dry seasons for the water samples from the different water sources and sampling points are within the allowable range except for turbidity and color during and just after typhoons and prolonged strong rainfalls. As to microbiological parameters, samples from the sources, storage tank, and distribution line have a very high total coliform count, and Escherichia coli content for both seasons. For heterotrophic plate count, only the water samples from Balabag Spring for both wet and dry seasons, from the storage tank during the wet season, and from Gakhan Spring during the dry season have acceptable values. Findings indicate the high vulnerability of the water sources to microbial contamination. Thus, water in all sources is not potable and is therefore not recommended for drinking purposes in its present condition. To address the water supply quality problems, filtration systems may be included in the water system design, the intake tanks, or a new reservoir.