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Swollen cellulose fibres isolated from water hyacinth were utilized in the synthesis of water hyacinth cellulose-graft-poly(ammonium acrylate-co-acrylic acid) polymer hydrogel (PHG). Acrylic acid (AA) partially neutralized with NH 3 was heterogeneously grafted onto swollen cellulose by radical polymerization reaction using N,N -methylene- bis -acrylamide (MBA) as the cross-linker and ammonium persulphate (APS) as the initiator. The reaction conditions were optimized through assessment of grafting parameters such as grafting cross-linking percentage (GCP), percentage grafting cross-linking efficiency (%GCE) and water absorption tests. Characterization of the copolymer by Fourier Transform Infra-red (FTIR) spectroscopy revealed successful grafting of the monomer onto cellulose. Transmission electron microscopy (TEM) image of acetone-extracted PHG displayed micro-porous structure. The optimized product swelled in distilled water up to 165 times its own dry weight. The swelling was influenced by the pH and presence, nature and concentration of ions. The hydrogel had the capacity to retain moisture in soil, and degradation testing revealed a higher mass loss in cellulose grafted copolymer compared to the copolymer without cellulose. Degradation by soil microbial isolates showed significantly higher (P ≤ 0.05) accumulation of NH 4 + in the cellulose grafted copolymer up to 0.05% (w/v) from 40 to 100 h, relative to similar amounts of copolymer without cellulose. The use of water hyacinth, a notorious weed in Kenyan waters, to produce cellulose-based polymer hydrogels has not been explored and yet, it could form an effective and beneficial way of utilizing this plant. A mechanism of graft polymerization reaction has also been proposed. The synthesized product can be applied in agriculture and other fields where biodegradability and effective utilization of water is essential.

The monitoring of water quality for both domestic and commercial use is absolutely essential for policy formulation that affects both public and environmental health. This study investigates the quality of water of river Molo system which lies in the Kenyan Rift Valley. The river is considered a vital source of water for the residents and industrial activities in Nakuru and Baringo Counties. Six water samples were collected during the dry season of December 2017. Various physicochemical parameters were determined in situ by use of a portable pH meter. These parameters included pH, temperature, electrical conductivity and total dissolved solids (TDS). Anions such as fluorides, sulfates, phosphates, nitrates, chlorides, carbonates and bicarbonates were determined using conventional methods such as titrimetry and (ultra-violet visible) UV-Vis techniques. The cations including sodium, potassium, calcium and magnesium were determined using flame photometry. The results showed that the water had pH values ranging from 7.90 to 9.66 units, temperature ranged from 14.02 to 31.5 °C, while electrical conductivity ranged from 181 to 1637 μS/cm, TDS (69-823 mg/L), F (2.76-3.28 mg/L), sulfates (4.97-85.66 mg/L), phosphates (0.13-11.06 mg/L), nitrates (1.73-6.16 mg/L), chlorides (38.5-69.4 mg/L), carbonates (18-148 mg/L), bicarbonates (54-384 mg/L), sodium (19-1800 mg/L), potassium (8.9-121 mg/L), magnesium (4.8-106.8 mg/L) and calcium (13.4-77.4 mg/L). The pH, temperature, fluorides and sodium were above the World Health Organization permissible limits for drinking water in S4 and S5. All the water samples fall under bicarbonate or freshwater zone. The sampling points can be classified into five water types: Na-Mg-Ca-HCO 3 , Na-HCO 3 , Na-Ca-Mg-HCO 3-CO 3 , Na and Na-Ca-HCO 3-CO 3. Chemical indices such as sodium adsorption ratio, magnesium hazard, percent sodium and permeability index are reported. Accordingly, the findings from this work indicate that the river Molo water in general is good for irrigation.

In 2009, the City of Cape Town (CoCT) adopted a stormwater policy which mandates that new and existing developments should reduce the concentration of phosphorus and suspended solids in stormwater runoff by 45% and 80%, respectively, but offered no explicit guidance about how these water quality targets might be achieved. This study aims to contribute to the limited knowledge that exists about the performance of local plant species to treat stormwater. A large nursery-based study was conducted to investigate the performance of 9 locally-occurring plant species to remove orthophosphate ), ammonia (NH 3 ) and nitrate (NO 3 -) found in urban stormwater. Synthetic stormwater was applied to each species as well as a control consisting only of soil (Malmesbury shale). The discharge was collected from a drainage pipe at the base of each of the 150 containers. The results show that all species (excluding Ficinia) reduced the average concentrations of PO 4 -3 by 81% and NH 3 by 90%. By contrast, NO 3 -was reduced by an average of 69% (excluding by Elegia and Phragmites) with 8 of the 9 species removing significantly more than the control. The species that performed well for all three nutrients include Agapanthus and turf grasses, Stenotaphrum and Pennisetum. The results of the study highlight three important factors in the design of biofilters: that a substantial proportion of nutrients can be captured or absorbed by plants; that the soil medium is an important factor in the removal of PO 4 -3 and NH 3 ; and that plant choice is essential in the removal of NO 3 -. Future research should test plant species in both the laboratory and field settings, and should include additional contaminants such as household detergents, heavy metals and bacteria.

Athi River bentonite clay was activated using sulphuric acid at various acid concentrations, clayacid ratio, temperature and contact times. Optimization was based on palm oil bleaching performance. The chemical compositions of the raw clay and clay activated at different acid concentrations were analysed to investigate the extent of cation dissolution and exchange. From the results, the clay was classified as calcium bentonite. Both cation exchange capacity (CEC) and the apparent bulk density were found to decrease with increase in acid concentration. When palm oil was bleached at 90°C for 30 minutes using1% and 4% clay activated with 2M sulphuric acid , the bleaching performances obtained were 94.5 and 98% respectively. These results compared well with those of a commercial bleaching clay which was used as standard. The equilibrium data was analysed using Freundlich and Langmuir adsorption isotherms and the former was found to provide a better fit for the data. The calculated heat of adsorption indicated that palm oil bleaching by the activated clay was an exothermic reaction and a physico-chemical process. Sulphuric acid activation was found to be an effective method of improving adsorption performance of Athi River bentonite clay and the activated product is a viable alternative to imported commercial bleaching earth.

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