Upflow anaerobic filters fed acetate and propionate, and completely mixed, suspended growth reactors fed acetate, propionate, lactate, and glucose were used to investigate the effect of electron donor and reactor type on the interaction between sulfate‐reducing bacteria (SRB) and methanogens. Organic loading rates of 0.25–0.50 g chemical oxygen demand (COD)/L · d were used in suspended growth systems and 1.0–5.0 g COD/L · d in filters. COD/sulfur ratios ranged from 20/1 to 2/1 for completely mixed reactors, and 20/1 to 8/1 for anaerobic filters. Results indicated that organisms involved in the conversion of lactate and glucose into simpler products were not affected by sulfide toxicity. Levels of 60–75 mg sulfur/L of hydrogen sulfide and 150–200 mg/L of dissolved sulfide (DS) caused stress in all suspended growth reactors; 100–150 mg sulfur/L of hydrogen sulfide and 200–400 mg DS/L could be tolerated in lactate and glucose systems, although with diminished COD and sulfate removal. For similar loading conditions, lactate and glucose systems had higher DS levels than acetate and propionate systems. A cyclic pattern of variation of DS and hydrogen sulfide with volatile‐acids COD (VACOD) was observed in long‐term experiments with suspended growth reactors. Anaerobic filters were able to tolerate higher DS and hydrogen sulfide levels than suspended growth reactors. A propionate‐fed filter could withstand more than 150 mg hydrogen sulfide/L of hydrogen sulfide and 1000 mg DS/L, and an acetate‐fed filter could tolerate more than 125 mg sulfur/L of hydrogen sulfide and 400 mg DS/L.

Agriculture is one of the main economic activities for Kenyans; the wastes from agriculture are minimally used. Among the crops grown in Kenya is the banana and produces about one million tonnes of bananas yearly, mostly for local consumption, of which the banana herb produces the fruits once in a lifetime, thus the stem becomes waste afterward. The waste from the banana plant includes leaves, stems, peduncles, peels, and rejected fruits. The banana waste is organic and thus is suitable for anaerobic digestion in which the solid digestate has suitable nutrients to be used as fertilizer. Batch fermentation at the mesophilic temperature range was carried out in triple determinations, this also applied to the blank sample. After the batch test was complete, the pH of the fermentation residue was measured electrochemically using a pH meter. The COD of the residue (both Solid and liquid) was also determined. Analysis of the biogas produced by gas chromatography enabled the methane part of the gas to be calculated.

Ruiru, a town within the metropolitan area of Nairobi Kenya, has experienced rapid urbanization which has generated a lot of challenges and problems – economically, socially, and environmentally The Purpose of this research was to study the impact of mega infrastructure on the hydrology of Ruiru and Kamiti rivers. The catchment area was defined by River gauging station (RGS) 3BB12 on River Kamiti and delineated using the RGS as the catchment outlet and was based on SRTM void filled Digital Elevation Model (DEM).  Data sets utilized in the study were landsat images, google earth images, river flow data obtained from from water resources authorities (WRA), river abstraction records, water production data and rainfall data. Various GIS methods employed to analyze the data included normalized difference built up index (NDBI), hydrological characterization using the threshold method, change detection, and GIS software (ILWIS and Grass GIS). The supervised classification built up index for the study area increased from 2.8% to 51.8% for the period under study. The mean flows over this period decreased from 2.2m3/s to 0.53m3/s. This indicated that there was a definite effect of change in land use to the river flow regime. However, to conclude that mega projects had a separate effect to ‘normal’ urban development would not have been correct. This is because the flow duration curves for the different periods (1958-1987, 1988-2000, 2005-2010, 2011-2016) showed a similar pattern with no abnormal changes seen in the previous 10-15 years. It is therefore recommended that developmental control be enforced. This will assist in mitigating against the negative effects of land use conversion. The present development control authorities need to be strengthened to enforce development control. The zoning guidelines and planning regulations form the basis for developmental control and should be enforced.

Mbumbuni community water scheme is served by surface runoff and ephemeral streams which is harnessed in an earth dam. The dam has been in existence for decades, and was facing a big problem of reservoir sedimentation from the heavily loaded runoff water. De-silting the reservoir or increasing the dam height would not be long-term solutions without a proper system in place to protect the dam by reducing future siltation through conservation works in the catchment area. An urgent need for protection of the catchment area of the dam arose, not only for conserving or improving the water source and the storage capacity, but also to enhance agriculture and the livelihood of the inhabitants. The conservation plan was develop using project approach method. This article describes a proposed conservation plan for the study area. Implementation of the conservation plan will improve water supply and increase the Dam lifespan through reduction in siltation.