Browsing by Author "Nzila, C"

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    Colour and Nutrient Removal from Textile Waste Water Using an Enhanced Fluidised Bed Bioreactor
    (2011) Nzila, C; Wambua, P; Githaiga, J; Tuigong, D; Kiriamiti, HK; Kiambi, S-L; Muumbo, A
    Textile waste water contains an array of chemicals with different biodegradation characteristics that often presents chronic colour and nutrient removal problems. Conventional and advanced methods commonly applied to treat textile wastewater are normally costly and require substantial investment costs. Enhanced anaerobic digestion (E.A.D) of textile wastewater, in comparison with other processes, seems to be most promising since it drastically reduces the organic and colour load of the wastewater at substantially minimised costs. This possibility offers textile industries an opportunity to cost effectively treat their effluents. This study evaluated colour and COD removal from raw textile waste water by means of an enhanced fluidised bed bioreactor. The enhancement of the bioreactor entailed pretreatment of the raw waste water using a coagulant (AlCl3) and a polyelectrolyte organic flocculant (Calflock 2900) to remove the suspended solids. The enhanced system was operated semi-continuously under laboratory conditions for 1680 hours. The fluidised bed anaerobic bioreactor was operated at a Bv of 2.6g COD/L.d and HRT of 12 hours. The enhancement process on average achieved respectively 40 ± 13 per cent and 68 per cent COD and colour removal efficiencies. The combined system on average achieved 72 ± 7per cent and 87 ± 4 per cent COD and colour removal efficiencies respectively however the bioreactor produced a low amount of biogas. The bioreactor operated without the need to discharge regularly the biological excess of sludge produced. The implementation of the combined system proved to be quite promising thus a new approach for the treatment of textile wastewater is thus proposed.
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    Development of a Renewable Energy Database System for East Africa – Survey on Biogas Usage and Potency of Various Agricultural Bio-wastes in Kenya
    (2014) Nzila, C; Muasya, R; Muumbo, A; Kiriamiti, K; Githaiga, J; Dewulf, J
    Kenya being an agricultural based economy produces vast amounts of agricultural bio-waste such as maize/corn stalks, rice and wheat straws, tea and coffee waste, sugarcane, banana and barley residues, sisal and cotton wastes as well as other forest residues. Most of these residues are regarded as of no immediate value hence they are wasted in the farms through burning or uncontrolled decay thus leading to nutrient leakage and eutrophication to the surrounding water bodies as well as contributing to odour and green-house gas emission through release of volatile and un-burnt hydrocarbons. The main objective of the researchwas to identify and develop biogas data variables in Kenya through a structured use of anaerobic digestion as a means of producing biogas from agricultural bio-waste including animal manure and crop residues. The short term target of the project was a phased development of well-defined/structured data variables suitable for a multilayered database system on biogas energy in Kenya, which could later form a basis for the development of a real time biogas information dissemination platform that can be replicated in other regions across Africa. Literature review was done by means of desk-study and field surveys were conducted to gather qualitative as well as quantitative data for analysis and in-putting onto a Geographic Information System (GIS) based data mapping. Direct interviews were based on a schedule that employed a combination of direct site visits, emails and phone calls.Laboratory-based physical/bio-chemical characterization of biogas feedstock was also conducted. Discussions with diverse biogas stake holders elicited 100% support from respondents in addition to yielding an array of recommendations. The bio‐methane results further demonstrated the suitability of coffee pulp residue, cotton residue and maize stover as complementary biogas feedstock.The biogas quality in terms of hydrogen supplied (H2S) and methane (CH4) content was quite promising. The biogas H2S content (ppmv) for all the substrates ranged from as low as 105 (for maize stover) to 1100 (sugarcane leaves) whereas the CH4 content varied from 40% (sugar cane leaves) to 62%(cotton residue).Generally CH4 content is required to be above 50% whereas the presence of contaminants such as H2S is supposed to be less than 1000ppmv. From the results, biogas from coffee pulp residue, sugarcane bagasse, maize stover, cotton residue and banana stalks can be regarded as suitable alternatives for domestic biogas production.
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