Potential Impact of Wash Bay Effluent on the Water Quality of a Subtropical River

Washbay effluents have received scant attention as a potential source of water pollution globally. This study is the first to investigate the potential impact of the total wash bay effluent content released into river water in Africa. We investigated the potential ramifications of wash bay effluxent released off Charter Estates, Chimanimani in the Eastern Highlands of Zimbabwe on the water quality of the receiving subtropical Nyahode River by measuring selected water limnochemical aspects which included biological oxygen demand (BOD), chemical oxygen demand (COD), oil and grease, pH, sulphates, phosphates, iron, total suspended solids (TSS), dissolved oxygen (DO) and electrical conductivity (EC) once every 3 months from October 2011 to July 2012. The obtained mean levels of the limnochemical parameters from the Nyahode River were compared to the local Environmental Management Agency (EMA) and international World Health Organisation (WHO) effluent standards. Our results show that the control point and the off effluent discharge source downstream points in the Nyahode River had water quality parameters that were below the local EMA and WHO water quality threshold values. Cluster analysis showed a strong linkage in the values of water quality parameters measured at sampling sites 3 and 4 which were below the discharge point. Wash bay effluent released from the Charter Estate has an impact on some aspects of the water in the Nyahode River but the river has a functional self-purification capacity. Onsite industrial purification of wash bay effluent before discharge reduces its potential deleterious impact on water quality, river habitat integrity and aquatic biodiversity.

Assessment of Climate Change’s Impacts on River Flows in the Songwe Sub-Basin

River flow in the Songwe sub-basin is predicted to alter due to climate change, which would have an impact on aquatic habitats, infrastructure, and people’s way of life. Therefore, the influence of climate change should be taken into account when making decisions about the sustainable management of water resources in the sub-basin. This study looked into how river discharge would react to climate change in the future. By contrasting hydrological characteristics simulated under historical climate (1981-2010) with projected climate (2011-2040, 2041-2070, and 2071-2100) under two emission scenarios, the effects of climate change on river flow were evaluated (RCP 4.5 and RCP 8.5). The ensemble average of four CORDEX regional climate models was built to address the issue of uncertainty introduced by the climate models. The SWAT model was force-calibrated using the results from the generated ensemble average for the RCP 4.5 and RCP 8.5 emission scenarios in order to mimic the river flow during past (1981-2010) and future (2011-2100) events. The increase in river flows for the Songwe sub-basin is predicted to be largest during the rainy season by both the RCP 4.5 and RCP 8.5 scenarios. Under RCP 8.5, the abrupt decrease in river flow is anticipated to reach its maximum in March 2037, when the discharge will be 44.84 m3/sec, and in March 2027, when the discharge will be 48 m3/sec. The extreme surge in river flow will peak, according to the RCA4, in February 2023, in April 2083 under RCP 4.5, and, according to the CCLM4 and RCA4, in November 2027 and November 2046, respectively. The expected decrease and increase in river flow throughout both the dry and wet seasons may have an impact on the management of the sub-water basin’s resources, biodiversity, and hydraulic structures. The right adaptations and mitigation strategies should be adopted in order to lessen the negative consequences of climate change on precipitation, temperature, and river flow in the sub-basin.

Oil spill sorption using raw and acetylated sugarcane bagasse

In the recent decades oil spills in the aquatic environments are one of the major sources of environmental pollutions, which are steadily growing with the increase in oil consumption. Adsorption is a rapid and cost effective process to minimize the environmental impacts of oil spills and cleanup these pollutants. In this work, the crude oil sorption capacity was examined with raw sugarcane bagasse and acetylated sugarcane bagasse. Results show that the acetylated bagasse was significantly more oleophilic than the raw bagasse and acetylation reaction can increase bagasse oil sorption ability by about 90%. The maximum sorption capacities of acetylated bagasse were obtained about 11.3 g and 9.1 g in dry system(crude oil sorption) and oil layer sorption, respectively. The physicochemical characteristics of the sorbents such as composition, water solubility, moisture content and density were measured according to ASTM standard methods. Also Fourier transform infrared spectroscopy(FTIR) of raw and acetylated bagasse was performed to investigate the effect of acetylation on sugarcane bagasse structure.