t. itayama

The major sources of pollution along the Mukuvisi River are industrial effluents from Msasa, Graniteside, and Southerton industrial sites, sewage effluent from Firle sewage works, pesticide and fertilizer runoff from Pension and surrounding farms, and domestic and diffuse pollution from residential areas. The primary objective of this study was to assess the impact of point and non-point pollution sources on macroinvertebrates variability and investigate the seasonal water quality deterioration along the Mukuvisi River. To evaluate macroinvertebrate community diversity using South African Scoring System 5 protocol for rapid bioassessment of water quality. The combined application of benthic macroinvertebrates and physic-chemical parameters was the focus of this research to validate the water quality status of the urban River systems concerning emerging pollutants in urban areas.

  According to the Harare municipality pollution control strategy and surveillance, only twelve accessible sampling points were chosen along the river. Macroinvertebrate samples and physic-chemical measurements were collected once or twice a month, according to the city of Harare’s sampling schedule. The ancillary information, temperature, pH, and conductivity were measured on-site with a mercury bulb thermometer, a pH meter, and a conductivity meter, respectively. The standard South African Scoring System 5 sampling protocol was used for the sampling and identification of the macroinvertebrates community.

The early assessments showed that water pollution was, in the 1st place and as a primary issue, a biological matter, and its primary effects could have been traced to living organisms. Eutrophication in Manyame catchment, Harare, Zimbabwe is subjected to prolonged and cumulative ecosystem stress because of human activities, sewage disposal, and industrial discharges, among other pollution sources. The Phosphorus-P, Biological Oxygen Demand, Chemical Oxygen Demand, and Ammonia-NH3 (from 0, 6.9, 118, and 0 to 3.8, 81.9, 840, and 31 mg/L respectively) concentration increases downstream in both seasons. The Dissolved Oxygen saturation was 75% and 67% upstream in the dry-and-wet season and was reduced to 0% downstream in both seasons. The evaluation of macroinvertebrate diversity provided evidence that Mukuvisi River water was polluted based on the South African Scoring System, especially in the dry season.

The physic-chemical parameters were significantly related to macroinvertebrates diversity. In the assessment of river water quality, both macroinvertebrate indices and physio-chemical parameters can be sampled together to avoid bias. The results indicated that human activities from the upstream were inducing water pollution. Industries need to adhere to the wastewater discharge guidelines.

Water pollution and scarcity are becoming a serious challenge worldwide and methods of treating or recycling the wastewater are becoming expensive, especially in rural areas of least developed countries. An affordable wastewater recycling approach is imminent and should be cost-effective, using local materials to alleviate the water shortage and pollution challenges. The use of adsorbents from different biomass has been on the highway and tree barks are no exception for that matter. This research, therefore, intends to test the use of novel material’s capacity to remove Iodine from an aqueous solution under set conditions and use Bayesian statistics to validate the results as compared to the Frequentist approach.  This study is qualitative and developmental research where Bayesian and Conventional statistics were applied to complimentarly validate the results.  Kinetic models, Field Emission Scanning Electron Microscopy, and Energy Dispersive X-ray Spectroscopy were used to characterize the novel adsorbent to check for its potential and capability in removing Iodine from water. Akaike Information Criterion (AICc) was then used to select the best model. The findings demonstrated that the Bayesian approach was simultaneously applied with classical methods to compare their parameter estimation. Mupane biochar performed better than Mushuma, Pseudo-Second-Order model described both materials better with lower AICc values of 37.76 and 38.03 than other kinetic models respectively, indicating a chemisorption mechanism. Bayesian approach remarkably revealed slightly higher qt estimations of 40.712 and 41.639 mmol/g than conventional statistics with 40.01 and 40.29 mmol/g for Mushuma and Mupane biochar. Elovich model subsequently fit the data, henceforth demonstrating a heterogenous surface property with chemisorption phenomena. Field Emission Scanning Electron Microscopy and Energy Dispersive X-ray Spectroscopy exhibited C (81.93 mol% and 86.91 mol %) and O (16.12 mol% and 11.49 mol%) for Mushuma and Mupane respectively. Material performances were insignificant however, Mupane marginally outperformed Mushuma bark.  However, further examination is required in determining the surface area, adsorption isotherms, and functional groups available. This African tree-bark biochar promised to be good adsorbents of wastewater contaminants and their kinetic mechanisms can be a benchmark to suggest their applications as potential candidates for environmental-ecosystem-protection and water re-use strategy, especially in rural and urban areas.