A Water Quality Index (WQI) is a tool that describes the overall water quality by combining complex and technical water quality information into a single meaningful unitless numerical value. WQIs predict water quality since they reflect the impact of multiple Water Quality Parameters (WQPs) and allow for spatial-temporal comparison of water quality status. Most African countries employ adapted WQIs by modifying the original index (or indices) and propose their concepts for evaluating the quality of surface and groundwater, which is normally accompanied by irregularities. The current review examined the process(es) involved in WQI modifications for monitoring water quality in Africa, explored associated limitations, and suggested areas for improvement. A review of 42 research articles from five databases in the last ten years (2012–2022) was conducted. The findings indicated Weighted Arithmetic (WAWQI) and the Canadian Council of Ministers of Environment (CCMEWQI) as the most adapted WQIs. However, several limitations were encountered in WQI developmental steps, mainly in parameter selection and classification schemes used for the final index value. Incorporation of biological parameters, use of less subjective statistical methods in parameter selection, and logical linguistic descriptions in classification schemes were some recommendations for remedying the limitations to register the full potential of adapted WQIs for water quality monitoring in Africa.

Increasing human activities in coastal areas of Ghana have led to the degradation of many surface waterbodies, with significant consequences for the ecosystems in the affected areas. Thus, this degradation extremely affects the health of ecosystems and disrupts the essential services they provide. The present study explored the use of benthic macroinvertebrates as an indicator of estuarine degradation along the coast of Ghana. Water and sediment samples were collected bimonthly from Ankobra, Kakum and Volta estuaries for physicochemical parameters, nutrients and benthic macroinvertebrates. The findings revealed the dominance of pollution-tolerant taxa such as Capitella sp., Nereis sp., Heteromastus sp., Tubifex sp., Cossura sp. and Chironomous sp. in Kakum Estuary while pollution-sensitive taxa such as Scoloplos sp., Euridice sp., Lumbriconereis sp. and Pachymelania sp. in the Volta Estuary. The species-environment interactions showed dissolved oxygen, temperature, salinity, orthophosphate, nitrates, ammonium, electrical conductivity, turbidity, and chemical oxygen demand as the most significant parameters that complement the use of benthic macroinvertebrates as indicators of environmental quality in the studied estuaries. There were correlations of some benthic macroinvertebrate taxa with environmental factors in the estuaries suggesting low, moderate and high levels of pollution in the Volta, Kakum and Ankobra estuaries, respectively. Nevertheless, the study finds Kakum Estuary to be the ecologically healthiest estuary than the Volta and Ankobra Estuaries. Therefore, the study has shown benthic macroinvertebrates as a key indicator of ecosystem health alterations, and it is recommended that they should be incorporated with other environmental data for pollution monitoring in Ghanaian coastal waters.

Constructed wetlands (CWs) polish wastewater prior to discharge into aquatic receptacles. Size variabilities of substrates used in CWS may have effects on the treatment efficiencies though there is scanty information regarding this aspect in VSSF CWs. To address this knowledge gap, a laboratory scale mesocosm experiment was set up to investigate the potential of a VSSF CW to reduce organic matter and FIB using various gravel substrate aggregate sizes. This consisted of three gravel size treatment units; <12.5, 12.5-18 and 18-24 mm in triplicates. 70 liters of pre-treated wastewater from the final wastewater stabilization pond (WSP) of Egerton University’s WSPs system was added to the units, allowed to settle for 6 weeks for development of biofilms, followed by periodic feeding of equal wastewater quantity on weekly basis and influent and effluent samples collected for 8 weeks for analysis. Results disclosed reduction efficiency of 95.2, 94.3 and 88.4 % for E coli in the fine, medium and coarse gravel aggregates respectively. Less than 20 % reduction efficiency was recorded for BOD5 in all gravel aggregate sizes. There was no significant variation on performance of the three gravel aggregate sizes in reduction of both FIB and BOD5 (p˃0.05). Poor performance in BOD5 reduction was related to absence of wetland macrophytes in the study. The relatively high reduction efficiency for FIB was attributed to other factors and processes such as predation, mechanical interactions, starvation, microbial interactions and natural die-offs. The study recommends assessing the combined effect of increasing the retention time, use of wetland macrophytes and incorporating various gravel aggregate sizes in order to increase the efficiency of VSSF CW in reduction of FIB and organic matter.