This study investigated wastewater management using Vetiveria zizanioides planted in vertical flow constructed wetland (VFCW). Wastewater from the grit removal chamber and the primary sedimentation tank of Daspoort Wastewater Treatment Works was fed into six-pilot VFCW consisting of 1000-L plastic tanks having 500-mm-deep, 10–15-mm-diameter granite substrate planted with V. zizanioides. Irrigation of macrophytes using effluent from the grit removal chamber and primary sedimentation tanks was done after 3 months of planting and the VFCW monitored. Wastewater samples were collected and analysed using standard procedures. The pollution parameters of the initial sample were total alkalinity 297 ± 27.3 mg/L; COD 627 ± 149.0 mg/L; EC 82.53 ± 5.4 ms/m; free and saline ammonia 36.02 ± 4.1 mg/L, nitrate/nitrite 0.09 ± 0.1 mg/L; pH 7.66 ± 0.4; phosphate 3.07 ± 0.3 mg/L, sulphate 44.57 ± 3.1 mg/L; TDS 551 ± 37.8; TSS 319 ± 34.2 mg/L; and TKN 41 ± 6 mg/L. Percentage removal of 89.57, 98.34% TSS; 98.95, 98.62 free and saline ammonia; 89.87, 91.44% TKN; and 80.65, 58.02% COD for screen and settled wastewater, respectively, was obtained from the VFCW. VFCW using locally available V. zizanioides is a viable alternative for municipal wastewater treatment.

This study examined the spatial distribution and risk associated with the proliferation and indiscriminate establishment of petrol stations in Abeokuta metropolis, Nigeria. All effective parameters in petrol stations risks were identified and assessed using Williams–Fine and FMEA methods for petrol stations in the metropolis while structured questionnaire was administered on respondents near the petrol stations to elicit relevant information. Number of existing petrol stations, road networks and other spatial attributes served as input into the GIS environment with ArcGIS 10.0. Distances between road edge and petrol station, petrol station and residential buildings and between petrol stations were determined using preset criteria. The fire risk assessment revealed that 88 of the petrol stations had high risk (range: >201) while 20 and nine had medium (range: 201-101) and low (range: <100) risks respectively. Majority (113) of the 117 active petrol stations in Abeokuta have few or no functioning fire extinguishing systems, which make them vulnerable to fire incidences. Risk analysis indicated that distances between petrol stations and residential buildings in the metropolis does not comply with the 450 m distance standard. Majority were located within residential, commercial and educational land use areas where they constitute environmental risks including fire disasters, and soil and groundwater pollution.

The insufficient availability of safe water has emerged as a prevalent issue severely impacting public health in developing nations. Moreover, studies reporting the efficacy of treatment plants (TPs)—specifically Phragmites karka and Typha latifolia—in removing toxic elements in aquaculture wastewater are scanty. Therefore, this study is aimed at investigating the effects of hydraulic retention time (HRT), seasonal variations, and TPs on the removal efficiency of pollutants from a vertical subsurface flow constructed wetland (VSSF-CW) in Nigeria. The experiments spanned three seasons (November–December–January—NDJ; March–April–May—MAM; and July–August–September—JAS) of the year, with samples collected from the CW at 7 day intervals for analysis. The aquaculture wastewater was analyzed in the laboratory to determine its chemical and toxic compositions before and after the introduction of treatment plants. Three-way ANOVA was used to analyze the main and interactive effects between HRT, seasons, and TPs on the physicochemical properties of the CW’s effluents. The removal efficiency was determined to evaluate the performance of the constructed wetland in comparison to the treatment plants. Results showed that these constructed wetlands effectively removed contaminants, with significant differences (p < 0.05) mostly observed in the effects of treatment plant types and seasons on the chemical and heavy metal concentrations. This was further confirmed by the main effects of HRT, seasons, and treatment plant choice, which significantly (p < 0.05) influenced treatment efficiency. Removal efficiencies increased with longer HRTs, reaching peak removal efficiencies of approximately 69, 67, and 61% for Na, K, and Ca, respectively. The BOD and COD reached 85 and 90% removal efficiency, while removal efficiency of 100% was achieved for most heavy metals at 21 day retention time. In summary, the study found that TPs (Phragmites karka and Typha latifolia), HRT, and seasonal variation are important for treating integrated poultry and aquaculture wastewater in a VSSF CWs.

This study investigated the efficiency of macrophyte-based phytoremediation systems using Phragmites karka and Typha latifolia for the treatment of poultry–aquaculture wastewater and its suitability for irrigation reuse. Physicochemical parameters, heavy metals, and water quality indices were analysed using correlation analysis and Principal Component Analysis (PCA). Strong positive correlations were observed among turbidity, nutrients, biochemical oxygen demand (BOD₅), and chemical oxygen demand (COD), while dissolved oxygen (DO) showed significant negative relationships, indicating organic pollution-driven oxygen depletion. Heavy metals exhibited strong intercorrelations, suggesting common anthropogenic sources and similar removal pathways. PCA results revealed that the first three principal components (PCs) explained over 95% of the total variance, with positive values recorded from the first PC highlighting organic load, nutrient enrichment, and metal interactions as dominant factors controlling wastewater quality. The negative values of factor loadings obtained in the second and third PCs confirmed the roles of sedimentation, adsorption, microbial activity, and plant uptake in pollutant removal. Water Quality Index (WQI) values decreased drastically from highly polluted levels (>3000) in raw wastewater to <1.0 after 21 days of treatment, indicating excellent water quality. Sodium Absorption Ratio (SAR) also declined significantly, confirming a low sodicity risk. Both macrophytes demonstrated high treatment efficiency, with Typha latifolia showing slightly improved sodium reduction. Overall, the study highlights macrophyte-based systems as sustainable, cost-effective solutions for wastewater treatment and safe agricultural reuse.

The increase in world’s population has led to increase in waste generation and is a source of concern for stakeholders across the world. These wastes end up in dumpsites which undergo different stages of decomposition thereby producing Leachate which have a tendency of polluting groundwater. This study assessed biodegradability and Leachate Pollution Index (LPI) of dumpsite relative to its age. Three dumpsites Orile (O), Solous 3 (S3) and Solous 1 (S1) dumpsites with different ages: – less than 5, between 5-10 and greater than 10 years old respectively were studied. Leachate samples were collected from each dumpsite; Physico-chemical parameters: pH, chloride, Iron, Zinc, Arsenic, Total nitrogen, Chemical Oxygen Demand (COD), Biochemical Oxygen Demand (BOD5), Total Dissolved Solid, Electricity Conductivity and heavy metal: Lead, Chromium and Copper were analysed to determine the LPI while BOD5/COD was determined to ascertain the level of biodegradability of the dumpsites. The BOD5/COD results for O, S3 and S1 leachates were in the decreasing order of 0.37, 0.29 and 0.21 respectively while LPI results for: O, S1 and S3 leachate were 10.00, 11.20 and 15.68 respectively which were above the standard limit of 7.38. The results showed that O and S1 dumpsite leachate had least and highest sign of biodegradability respectively. The LPI result showed that O and S1 dumpsite leachates had the highest and the least pollution potentials respectively. Leachate from dumpsites less than 5 years has higher pollution potentials and lesser biodegradable than leachates from dumpsites more than 5 years. Leachate from O dumpsite will impact negatively on groundwater quality than leachates from S1 and S3 dumpsites. The age of a dumpsite leachate determines its pollution potential and biodegradability.

— Reservoir sedimentation is an important consideration for dams and reservoir integrity. Soil particles eroded from congruent catchments are usually deposited into reservoirs built for impounding water for different purposes. This study evaluated the sediment concentration and turbidity in Ofiki and Oyan rivers, south-west Nigeria. Sampling was done on the two rivers using equal-width-increment method between October 2020 and Septembers 2021. Results indicated that sediment concentrations range from 38.17- 401.67 with a mean value of 186.4 mg/L, and 9.67 – 421.75 mg/L with a mean value of 167.23 mg/L for Ofiki river and Oyan river, respectively. Turbidity ranged from 0.20 – 95.35 NTU with a mean value of 25.54 NTU and 0.01 – 83.90 NTU with a mean value of 18.92 NTU for Ofiki river and Oyan river, respectively. Simple linear regression of both parameters gave regression models C_(s^( = ) ) 85.26T^0.26 with R^(2 )=0.42 for Ofiki and C_s=3.95+92.48 with R^(2 )=0.51 for Oyan river. Turbidity and sediment were found to be higher during the raining season, and higher in Ofiki river than Oyan river