George Achieng

Productivity of sugarcane in Kenya has declined despite use of recommended production practices including introduction of elite high yielding and early maturing sugarcane varieties. Farmers continue to use recommended agronomic inputs for the old low yielding and late maturing varieties on these elite varieties. Nitrogen fertilizer rates in single or split doses for old varieties are still in use yet their appropriateness on new varieties remains untested culminating to decline in sugarcane productivity in Kenya. Currently, cane payment is based on delivered milling cane weight. The industry plans to change payment to a combination of quality and yields. Influence of agronomic inputs and timing of harvesting period on proposed mode of payment is unknown. Harvesting age in western Kenya remains 18-20 months after ratooning (MAR). However, optimal age that combines quality and yields is not documented. Influence of these agronomic practices on quality, yields and optimal harvesting ag...

The occurrence of heavy metals, dyes, micronutrients, phenols, pharmaceuticals, and personal care products (PPCPs) in water resources continue to raise environmental concerns since they are known to cause detrimental effects on living organisms even at low concentrations. Conventional wastewater treatment plants have also been pointed out as point sources of loading these pollutants into the recipient surface waters. Because of the non-biodegradable nature of heavy metals and the stable structure of dyes and PPCPs, these pollutants are persistent in the environment. Studies have shown that algae (micro and macro) present an alternative source of low-cost, efficient, and sustainable biosorbent for the removal of various pollutants from water either singly or in synergy with other wastewater treatment processes. This chapter is a brief review of recent studies on the use of algae-based biosorbents for the sequestration of heavy metals, dyes, and PPCPs from wastewater. Microalgae and m...

The objective of this work was to investigate the occurrence and fate of five heavy metals in water, sludge, and sediments from a conventional municipal wastewater treatment facility in Kisumu City, Kenya. The effluent quality was compared with the effluent quality parameters stipulated by the National Environmental Management Authority (NEMA) to assess the efficiency of the plant and potential effect of the discharged effluent on the recipient river. The levels of the heavy metals recorded in the sludge samples were significantly higher than those in the corresponding water samples. The order of the metal percentage removal efficiency (%R) from the treatment plant was Mg>Cu>Mn>Fe>Zn. It is concluded that the plant is a point source for Zn loading into the recipient waters which poses potential risk to end users downstream. The heavy metal-laden sludge was within permissible limits for utilization in agricultural lands.

The syntheses and characterization of fish scale biochar magnetic composites (FSB@Fe3O4) and their applications in the removal of indigo carmine dye from effluents are described. Preparation of the fish scale biochar magnetic composites, FSB@400 °C-Fe3O4, FSB@600 °C-Fe3O4, and FSB@800 °C-Fe3O4, was done following the chemical co-precipitation method. The adsorbents were characterized using peak optical absorbance, functional groups, magnetic strength, surface morphology, particle size, elemental compositions, surface charge, surface area, thermal stability, and crystalline phase, using ultraviolet-visible spectroscopy (UV-vis spec), Fourier transform infrared (FTIR) spectroscopy, vibrating sample magnetometry (VSM), transmission electron microscopy/scanning electron microscopy (TEM/SEM), energy dispersive X-ray (EDX), point of zero charge pH (pHpzc), Brunauer-Emmett-Teller (BET), thermo-gravimetric analysis (TGA), and powder x-ray diffraction (PXRD) techniques, correspondingly. The potential of magnetic composites for the abstraction of indigo carmine dye from wastewater was determined as a function of the initial concentration of indigo carmine dye, contact time, dye solution pH, adsorbent dosage, and solution temperature. The results demonstrated that the quantity (q) of indigo carmine dye adsorbed onto magnetic composites improved with a rise in initial dye concentration, adsorbent load, and solution temperature. Conversely, lower quantities of adsorbed dye were recorded at higher pH levels. The data fitted a pseudo-second-order kinetic model. The Langmuir isotherm gave the best fit (Langmuir>Freundlich>Redlich-Peterson>Toth>Hill>Sips>Temkin) suggesting a uniformly monolayer adsorption. Adsorption of environmental wastewater samples revealed that all the adsorbents can be used to effectively treat industrial wastewaters. The recycling data established that the adsorbents could be used for five consecutive cycles without significant loss of adsorption capacities.

The preparation and applications of Tilapia (Oreochromis niloticus) fish scale biochars (FSB) as an adsorbent in the removal of indigo carmine dye (ICD) from aqueous solutions is described. The biochars were prepared through pyrolysis over a temperature range of 200 °C–800 °C and characterized for surface charge, functional groups, thermal stability, particle size and morphology, elemental composition, crystallinity, and surface area by using pHpzc, Fourier transform infrared (FTIR) spectroscopy, thermo-gravimetric analysis (TGA), transmission electron microscopy/scanning electron microscopy (TEM/SEM), energy dispersive X-ray (EDX) spectroscopy, powder X-ray diffraction (PXRD) and Brunauer-Emmett-Teller (BET) techniques, respectively. Batch experiments were carried out to determine the variation of adsorption process with initial dye concentration, contact time, initial solution pH, adsorbent load, temperature and adsorbent pyrolysis temperature on the removal of the dye. The percen...

This chapter describes an up-to-date critique of the use of adsorption as a wastewater treatment technique for the removal of dyes. The topics range from the classification of dyes, their occurrence in water and toxicity, various treatment methods, and dye adsorption dynamics onto agricultural wastes and inorganic adsorbents such as clay and metal oxides and adsorption onto microbial biomass under varying operational conditions. It is demonstrated that the discussed materials form alternative adsorbents for dye adsorption from aqueous solutions with comparable or better removal efficiencies relative to the non-renewable coal-based granular activated carbons; they are cheap and abundant. The relative performance of the adsorbents under different environmental parameters for dye removal has also presented. The deductions made and alluded to from various kinetic and adsorption isotherm models are also discussed. The chapter presents the past, present, and suggestions for future conside...