67 Records out of 22207 Records

Physico-chemical and bacteriological quality of selected water sources in Kithimani area, Yatta district, and efficacy of common water treatment methods

Author: Sila, Onesmus Nzung'a

Awarding University: Kenyatta University, Kenya

Level : MSc

Year: 2011

Holding Libraries: Kenyatta University Moi Library ;

Subject Terms: Kithimani Area, Yatta District/Water/Water treatment ;

Abstract:

This study was carried out to determine the physico-chemical and bacteriological quality of water from various sources in Kithimani location and explores the effectiveness of common water treatment methods. Selected metals and non-metals ions were determined colorimetrically while turbidity was measured using a turbidimeter. pH, electrical conductivity, dissolved oxygen (DO) and temperature were measured using a portable universal multiline P4 WTW meter while total alkalinity was determined titrimetrically. The load of coliform bacteria contamination was determined by Millipore filtration method. Screening for the presence of pathogenic bacteria was carried out using standard methods. The levels of the properties investigated were each compared with the recommended drinking water standards according to Kenya Bureau of Standards (KEBS) and World Health Organization (WHO). The most contaminated water source identified based on the faecal coliform colony count was subjected to mechanical filtration and solar irradiation and changes in their physico-chemical properties and bacteriological load determined, Among the physico-chemical properties investi~ated in selected water sources, levels of alkalinity (range; 5.0 -196.3 mg CaC03 L' ), sulphates (range; 0.2 -124.3 mg LOI), chlorides (range; 0.0 -94.0 mg LO fluorides (range; 0.0 - 0.15 mg LOI) and zinc (range; 0.01- 0.3 mg Lol) did not exceed the upper limit for drinking water according to the KEBS and WHO standards. Manganese (range; 0.02 - 1.79 mg Lol) and copper (range; 0.0 - 2.2 mg LOI) concentration in water samples from most sources studied exceeded the maximum rrmissible concentration according to KEBS and WHO (0.1 mg Lol and 0.05 mg L- respectively) for safe drinking water. Levels of mean turbidity (0.78 and 0.65 NTU), color (0.0 mg pt Lol) and nitrates (7.99 and 7.01 mg Lol) in borehole and rainwater did not exceed the maximum permissible level for drinking water set by KEBS and WHO. Vibrio cholerae was detected in Athi and Kauthulini rivers only. Shigella SP'J Salmonella SP'J Klebsiella sp., Streptococcus faecalis and Clostridium perfringens were isolated from the samples of most water sources except in borehole and rainwater. The mean range for total coliforms and Escherichia coli for the water sources were 10 to 23,830 CFU per 100 mL and 10 to 3480 CFU per 100 mL respectively. which exceeded the maximum permissible limit of 0 CFU 1100 mL for KEBS and WHO. There was no significant difference in colour (P = 0.723), sulphates (P = 0.999), temperature (P = 0.999) and conductivity (P = 0.058) among the water sources. A significant difference in mean values of salinity. alkalinity. DO. turbidity. nitrate nitrogen. chlorides, calcium, zinc. copper and iron among water sources (P < 0.05) was noted. The results obtained after treatment revealed that solar irradiation killed most of the pathogenic bacteria after exposure for eight hours but had no impact on the physico-chemical properties except nitrates (from 24.5 to 8.0 mg LOI). Mechanical filtration reduced total coliforms and E. coli by 30 %. It also reduced the loads of Zn, Cu, MIl, Pb, Fe, nitrate nitrogen and turbidity of the water treated to an almost potable state. The study concludes that most water sources in Kithimani do not meet the potable water standards according to KESS and WHO. The results showed no significant variation in overall bacteriological water quality during dry and wet seasons (between low and high rainfall months). Finally. water treatment using mechanical filtration system and solar disinfection was found to be very effective in reducing the bacterial load.

Investigating removal of pesticide and natural organic matter from water by ultrafiltration and nanofiltration membranes

Author: Riungu, Joy Nyawira

Awarding University: Jomo Kenyatta University of Agriculture and Technology, Kenya

Level : MSc

Year: 2011

Holding Libraries: Jomo Kenyatta University of Agriculture and Technology Library ;

Subject Terms: Pesticides/Water treatment/Filters/Toxicity/ ;

Abstract:

The presence of humic acid (HA) and pesticides in water has for long posed a cballenge to researchers in the field of water/ wastewater treatment Owing treatment processes such as disinfection by chlorination, the presence of HA in water leads to formation of disinfection by-products that may be carcinogenic. Presence of pesticides in water is of significant health concern in Kenya especially in hoticultural production areas where chemicals are applied throughout the growing season. The removal efficiencies of such chemicals from water can be enhanced by application of membrane fitration. This research work investigates removal of humic acid and pesticide (atrazine) from water by membrane filtration and photocatalytic oxidation using two forms of Titanium Dioxide (Ti(h) catalyst; solution and powder form. A laboratory cross flow filtration unit was used to investigate; the retention of humic acid and atrazine by the membranes, the effect of catalyst on membrane permeate flux and ability of the catalyst to clean fouled membranes. Three types of Ultrafiltration (UF) membranes; polysulphone based (pS 1 OOH), and regenearted cellulose acetate based (C30H and CIOOH) were used to investigate the removal of humic acid. Removal of atrazine from water was investigated using three Nanofiltration (NF) membranes; NF90, NF270 and NTR72S0. Atrazine filtration was carried out at three different feed solution pH. Monitoring of membranes permeate flux and % retention was evaluated by monitoring the Total Organic Carbon (TOC) and flux of the permeate. Controlled bench scale photo reactor cell experiments were carried out using Titanium Dioxide (Ti(h) catalyst; (Ti(h, solution and Ti(h, powder) as photocatalyst to investigate degradation of HA. The ability of the catalysts to degrade humic acid in presence and absence of Ultra-Violet (UV) radiation was the major interest in thesis research. The HA degradation was monitored by measuring the TOC and UV absorbance of the sample. The performance of the catalyst was evaluated by calculating the reaction rate constants. In humic acid filtration, PS I OOH membrane recorded TOC removal efficiencies of over 9()01o. C I OOH had higher flux but lower retention than PS I OOH even though they had same Molecular Weight Cut-Off (MWCO). C30H had higher flux and better retention than ClOOH. Membrane material, MWCO and hydrophillicity were found to influence the rejection of HA. Rejection of atrazine by NF membranes resulted in NF90 showing the best performance with efficiencies of over 90010 in all conditions tested. NF270 and NTR7250 performance was affected by changes in solution pH and both showed. varying retention. In investigating the influence of catalyst in the degradation of HA, the Ti<h solution showed higher degradation efficiency than Ti~ powder both in the presence and absence of UV radiation. This observation was attributed to the differences in surface area between the two catalysts when at the same concentration. Cleaning of membranes fouled by HA by the two catalysts yielded good results but mainly depended on level of fouling, catalyst concentration and type of catalysts. When. distilled water was used to clean membranes fouled by 100 ppm HA feed solution, the range of restoration of original water flux varied between 72% - 77% for all tested membranes. Cleaning using Ti<h solution yielded good results with the restoration of original water flux ranging from 86%- 100010 for all membranes and on all tested conditions while for Ti<h powder the restoration ranged between 76% - 96%. Addition of Ti~ solution on feed solution during filtration did not have much effect on permeate flux even though there was an increase in rejection. The presence of Ti~ catalyst increased the permeate flux more when the UV lamp was turned on than when the lamp was off for all the tested membranes. Findings from this research show that UF membranes are efficient in eliminating HA from water while NF membranes are e

Effect of alum treatment and Ph adjustment on turbidity and levels of selected ions in grey water from Githurai, Kenya

Author: Skudi, Joseph Bwire

Awarding University: Kenyatta University, Kenya

Level : MSc

Year: 2011

Holding Libraries: Kenyatta University Moi Library ;

Subject Terms: Githurai, Kenya/Water treatment ;

Abstract:

Increase in population results to an increase in the volume of grey water generated, thus decreasing the availability of fresh water. In Kenya and developing countries acute water shortages are extremely experienced consequently resulting to water rationing and increase in water prices by water vendors. Therefore treatment of the grey water generated, for reuse in toilet flushing and laundry work could reduce fresh water demands. This study therefore proposed to determine the effect of alum treatment and pH adjustment in lowering turbidity and the levels of ions contaminants such that treated grey water could be reused for laundry and toilet flushing. The study was conducted in Githurai, peri urban settlement of Nairobi, densely populated and associated with unsafe disposal of grey water on to the ground. The inorganic contaminants of grey water occurs mainly in form of cations of lead, mercury, calcium, magnesium, manganese, ferrous and anions of nitrates, sulphates, chlorides, phosphates and fluorides. Therefore the levels of inorganic cations. were determined in the raw greywater and after treatment with alum and pH adjusted. It was found out that, turbidity in raw grey water was above the prescribed limits for potable water by Kenya Bureau of Standard (KEBS). Cations of Fe in all types of grey water were found to be above O.3mg/L, Mn were found to be slightly above OAmg/L in bathroom and laundry, Ca and Mg were found to be above 60mg/L, Pb was found to be lower than O.Olmg/L in almost all types of grey water and Hg ions were found to be lower than O.Olmg/L in almost all types of grey water. Upon filtration and pH adjustment in the range of 6.5 to 8.5 units, turbidity and levels of ions were within the prescribed limits by KEBS. At these levels the water could be used for toilet flushing and laundry without staining clothes and toilet fixtures thus meeting the objectives for treating raw grey water. This implied fresh water used for flushing toilets and laundry could be spared for cooking and drinking and this could significantly lower fresh water demands. The results of this study could go a long way in achieving Millennium Development Goal and consequently Kenyan vision 2030 if the community is sensitized and policies put in place.

Bacteriological and physico-chemical quality of water from various sources in Samburu District and efficacy of selected plant products in water purification

Author: Kipkemboi, Cheluget

Awarding University: Kenyatta University, Kenya

Level : MSc

Year: 2011

Holding Libraries: Kenyatta University Moi Library ;

Subject Terms: Samburu District/Water treatment/Plants/ ;

Abstract:

Limited access to safe drinking water and information on water quality in sparsely populated arid and semi-arid regions has contributed to frequent outbreaks of diarheal disease. There is therefore urgent need to determine the bacteriological and physico-chemical quality of water in various sources in these regions. This study was undertaken in order to determine water quality in Wamba Division of Samburu District and to asses the efficacy of plant extracts in purifying water. Bacteriological analyses was carried out using multiple tube fermentation technique and heterotrophic plate counts technique, while physicochemical analyses were carried out using standard methods. Qualitative bacterial determination confirmed the presence of thermotolerant eoliforms, Shigella and Salmonella spp. in most water samples examined. The same samples frequently recorded high levels of turbidity (range,S to 6100 NTU), alkalinity (range, 20 to 1577 mg L-! CaC03) and low salinity (range, 0 to 0.2 ppt). Faecal coliform load in dry river bed wells (mean 471.63) was higher than in the other categories of water sources (dams, rivers, springs and tap water). This study also found that the boreholes had the highest mean conductivity (830.8 )lS em') while wells had the widest range (4.6 to 5940.0). High levels of conductivity in water from groundwater sources can be attributed to the long period of contact between the water and mineral sources. Water treatment with alum, sodium hypochlorite and extracts from Boscia coriacea Pax. Maerua decumbens (Brogn.) Dewolf roots and Moringa oleifera Lam. seeds resulted in a varied reduction of bacterial and sediment loads of the water samples. Overall, all the treatments were found to be effective in reducing bacteria and sediment load in water samples collected from various sources, except for some unidentified residual bacteria that resisted the disinfection properties of plant extracts. Changes in the percentage load of heterotrophic plate counts (HPC) among the treatments used differed significantly (P < 0.05, DF = 5). Overall mean percentage change in HPC were 26.51, 46.00, 30.20 and 14.50 for M Oleifera Lam., M decumbens, B. coriacea and the control respectively compared to 74.76 and 90.95 in the case of alum and sodium hypochlorite in the same order. These values indicate that changes in bacterial density during water treatment may be due to loss of viability or alteration in eulturability. Results obtained in this study further indicated that there was no significant difference in water turbidity reduction (P < 0.05) by M oleifera, M decumbens and B. coriacea. Both B. coriacea and M decumbens chelants resulted in a high removal of the initial turbidity by 50.36 % and 43.87 % respectively during 30 minute treatment period while M oleifera were 40.53 %. As such the three species can be considered potentially useful chelants, and should be subjected to further study. During this study, it was noted that, plant extracts changed the water pH. This observation suggests that pH change possibly plays a vital role in inactivating bacteria in water. Bacteriological water quality analyses revealed that water from most sources had bacterial loads that exceeded the WHO value/guidelines for drinking water. Isolated species of E. coli, Salmonella and Shigella spp from water samples also showed varied antibacterial sensitivity to crude plant water extracts. This study therefore concludes that water from most sources is contaminated and must therefore be treated before consumption. It is recommended that further studies be conducted to identify the mechanism and active ingredients present in the plant extracts responsible for reducing sediment and bacterial load in water and how their efficacy is affected by the physico-chemical properties of water.

Fuzzy based decision support method for selection of sustainable waste water treatment technologies

Author: Kamami, Martin Igecha

Awarding University: Jomo Kenyatta University of Agriculture and Technology, Kenya

Level : MSc

Year: 2011

Holding Libraries: Jomo Kenyatta University of Agriculture and Technology Library ;

Subject Terms: Water/Models/Water treatment/Decision support systems/ ;

Abstract:

Inadequate decision support tools have lead to selection of inappropriate and unsustainable wastewater treatment technologies. There is therefore the need to develop tools that would improve decision making process in selection of appropriate wastewater treatment technologies. The broad objective of this research work was to develop a decision support method for selection of sustainable wastewater treatment technologies. The specific objectives were to investigate performance data for wastewater treatment technologies, develop a decision support method (DSM) for evaluating performance of technologies, and to validate the method. The decision support method was developed through evaluation of performance of wastewater treatment technologies against environmental and economic indicators. Fuzzy logic techniques were used in order to support decision making under uncertainty. The method was validated through a training tool in wastewater treatment known as ED- WAVE which was developed by a consortium of European and Asian countries. Also, independently collected data from three wastewater treatment plants in Kenya were used in the validation process. The Decision Support Method (DSM) relied on performance evaluation in order to rate wastewater treatment technologies. This was an improvement on existing decision support tools such as ED-WAVE that relied on retrieval of past performance data in order to arrive at a solution when a new treatment case was presented. Decision support method enabled performance of a single treatment unit within a treatment sequence to be rated. Also the overall performance of a treatment sequence could be rated through DSM hence allowing for any required improvements on performance to be incorporated .in design. Through application of DSM, the performances of wastewater treatment plants in Nairobi, Nakuru and Thika were rated as 'Good'. Using DSM analysis, additional technologies that could improve the rating of treatments plants in Nairobi, Nakuru and Thika from 'Good' to 'Excellent' were investigated. The Decision Support Method provided a more reliable method for wastewater treatment technology performance rating and hence selection as compared to ED- WAVE. Further improvements on the tool could be achieved through testing and validating more case studies and treatment sequences.

The potential of arrowroots (Colocasia esculenta) in phytoremediation of heavy metals in the Meru region

Author: Kimathi, Erastus Tuerandu

Awarding University: Jomo Kenyatta University of Agriculture and Technology, Kenya

Level : MSc

Year: 2011

Holding Libraries: Jomo Kenyatta University of Agriculture and Technology Library ;

Subject Terms: Arrowroot USE Colocasia esculenta/Taro USE Colocasia esculenta/Meru/Meru County/Metals/Gachioma River, Kenya/Karumanthi River, Kenya/Pollution/Water treatment/Colocasia esculenta ;

Abstract:

Potential health hazard implications of heavy metals in taro/arrowroot (Colocasia esculenta) are imminent especially if taro is cultivated in heavily polluted water bodies due to the fact that taro plant bio-accumulate heavy metals. Determination of heavy metals in food crops is important in order to establish their concentration levels. This study sought to investigate the presence and concentration of heavy metals: Cadmium, Chromium, Copper, Mercury, Manganese, Lead and Zinc in the leaves and corms of the taro/arrowroot plant and the corresponding water and sediments from Gachioma and Karumanthi rivers in Meru Town ofMeru County. The concentration levels of these heavy metals in the plant were determined to assess whether taro can accumulate them to toxic levels. Taro corms and leaves together with water and sediment samples were collected along the two rivers. The solid samples were first dried in the sun then in an oven and ashed in the muffle furnace. The residue was leached from the vessel using hot concentrated hydrochloric acid then digested using a mixture of nitric, perchloric and sulphuric acids in a volume ratio of 3:1:1. The samples were analyzed at JKUAT Chemistry laboratories using the Buck Scientific Atomic Absorption Spectrophotometer (AAS) model 210 VGP. Microsoft Excel Computer Software was used to analyze the data. Analysis showed that concentration of mercury was below detection limits in all the analytes from the two rivers. Cadmium concentration levels in water from the two rivers were below detection limits. The study showed that concentration of chromium was highest in Gachioma River with a mean of 0.162 ? 0.003 ppm while the concentration for all other metals in the two rivers was below 0.12 ppm. In the sediments, the metal with the highest concentration was manganese in Gachioma River sediments which ranged between 4.755 and 11.000 ppm with a mean of 7.824 ? 0.172 ppm. The metal with lowest concentration in the sediments was cadmium in Gachioma River which ranged between 0.036 and 0.054 ppm with a mean of 0.048 ? 0.002 ppm. Zinc had the highest concentration in corms collected from Karumanthi River whose range was between 0.498 and 1.726 ppm with a mean of 0.88 ? 0.014 ppm. The metal with lowest concentration in corms was lead with a mean of 0.02 ? 0.0002 ppm and ranged between 0.008 and 0.026 ppm. The heavy metal with highest concentration in the leaves was manganese in the leaves of corms collected from Karumanthi River which ranged between 1. 73 0 and 3.776 and a mean of 2.68 ? 0.022 ppm. Lead had the lowest concentration in the leaves of taro collected from Gachioma River which ranged between 0.010 and 0.150 ppm and a mean 0[0.012 ? 0.00 Statistical analysis indicated that both leaves and corms bio-accumulated heavy metals. Results indicate that the plant can accumulate heavy metals if grown in heavily polluted water bodies. These results showed that the amounts of heavy metals in the two rivers were very low and did not pose any potential health hazard to consumers as they were below the and National Environmental Management Authority (NEMA) permitted levels. The potential use of the plant in water treatment is worth further investigation.

Source waste reduction : A case study on waste minimization at Beverage services Kenya limited ( BSK)

Author: Kinuthia, Richard Karori

Awarding University: Jomo Kenyatta University of Agriculture and Technology, Kenya

Level : MSc

Year: 2011

Holding Libraries: Jomo Kenyatta University of Agriculture and Technology Library ;

Subject Terms: Beverage Services Kenya Limited/Waste disposal/Waste materials/Water treatment/ ;

Abstract:

The extraordinary growth of waste globally is an indicator that creating waste, rather than enhancing it is more popular. The amount of money spent in disposing of the waste generated, dwarfs the amount spent to reduce it. The reduction of waste generated at the source can be a solution to the current crisis facing most local municipalities and the country at large. Reduction of waste at the source provides avenues and management practices that ensure waste is minimized. This project has studied waste (solid and water) generated at Beverage Services Kenya Limited (BSK), a plant involved in the production of carbonated and non-carbonated products in polyethylene terephthalate (PET) and tetra package containers. To realize this goal, the entire process was divided into distinct units of operation based on the different processes in which the raw material inputs and the process outputs were evaluated to yield a material balance. The material balance indicated the efficiency of the entire process that involved handling and conversion of the raw materials to finished products. Synthesis of the material balance indicated processes with high inefficiencies resulting in high waste generation. Through a waste audit in the specific processes, corrective measures were devised to address the inefficiencies in six out of the fifteen process inputs identified. The implementation of the corrective measures in the six selected inputs resulted in a reduction of waste in the different processes. The preforms had a +0.6% improvement in yields equivalent to a annual savings of nine hundred thousand Kenya shillings. Sugar had a +0.25% yield improvement equivalent to one hundred thousand Kenya shillings savings. Strategic ingredients had a savings of half a million Kenya shillings equivalent to a +3.7% yield improvement. Water had a 3.8 million liters savings equivalent to slightly over half a million Kenya shillings savings. Carbon dioxide had a +14.1 % yield improvement equivalent to over five hundred thousand Kenya shillings savings. The packs had a +5.5% yields improvement equivalent to five million Kenya shillings savings. The result of the entire project was tabulated and analyzed using statistical process control (SPC) charts. At the end of the project, the waste treated outside the plant reduced from ten tonnes in January 2009 to three tonnes in the month of October and November 2009 translating into a 70% waste reduction. The project thus demonstrated that it is possible to reduce waste at the source in a small scale approach such as this case study done at BSK, hence can be extended to cover large scale options like municipalities and the country at large. The project at the end demonstrated the environmental and economic beneficial that can be realized.

Determinants of adoption of household drinking water treatment methods in Winam Division, Kisumu East District, Kenya

Author: Otieno, Richard

Awarding University: University of Nairobi, Kenya

Level : MA

Year: 2011

Holding Libraries: University of Nairobi Jomo Kenyatta Memorial Library ;

Subject Terms: Winam Division, Kisumu East District ; Drinking water ; Water treatment ; Socioeconomic factors ; Households ;

Abstract:

This research project report is about the study of determinants of adoption of household drinking water treatment methods in Winam Division, Kisumu East District, Kenya. In many parts of the developing world, drinking water is collected from unsafe surface sources outside the home and is then held in household storage vessels. Drinking water may be contaminated at the source or during storage. Strategies to reduce waterborne disease transmission must safeguard against both events. Access to safe drinking water is essential to health, a basic human right and a component of effective policy for health protection. In Kenya, diarrhoeal diseases are among the top ten (10) causes of morbidity and mortality. Diarrhoea is ranked number three (3) in most rural public health facilities. According to the Ministry of Health (MOH) National Health Sector Strategic Plan (2005 - 2010), treating water at the household level has been shown to be one of the most effective and cost-effective means of preventing waterborne disease in development and emergency settings. Promoting household water treatment and safe storage (HWTS) helps vulnerable populations to take charge of their own water security by providing them with the knowledge and tools to treat their own drinking water. The purpose of the study was to investigate determinants of adoption of household drinking water treatment methods in Winam division, Kisumu East district, Kenya. The objectives of the study were to: - Investigate the extent to which household socio-economic status determines adoption of household drinking water treatment methods in Winam Division, Kisumu East District; Examine how knowledge on household drinking water treatment methods determines adoption of household drinking water treatment methods in Winam Division, Kisumu East District; Determine the extent to which accessibility to household drinking water treatment methods determines adoption of household drinking water treatment methods in Winam Division, Kisumu East District; and Assess how source of household drinking water determines adoption of household drinking water treatment methods in Winam Division, Kisumu East District. The study employed a descriptive survey study design, using both quantitative and qualitative techniques of data collection; the quantitative technique answered occurrence, while the qualitative technique sought to answer the ''why?'' aspect of the study. The quantitative technique involved the use of questionnaires while the qualitative technique involved the use of key informant interviews (KIIs). The study used a sample size of 384 households. The researcher employed multi stage random sampling to arrive at the sample size. Quantitative data was analyzed using descriptive statistics, including frequency tables and cross tabulations. Statistical Package for Social Scientists (SPSS) software version 17.0 was used to aid the analysis of the quantitative data. Qualitative data was grouped into respective themes and described in verbatim to enhance deeper understanding of the description of the quantitative data, guided by the study objectives and questions. From the discussions on the findings, the study concluded that household socio-economic status, knowledge on household drinking water treatment methods, accessibility to household drinking water treatment methods and household drinking water source determined adoption of household drinking water treatment methods. The study report recommends that health promoters should design messages focusing on risks of not treating drinking water and the benefits of treating drinking water. Public health workers should also train community health workers on effective delivery of messages on household drinking water treatment methods and design a sustainable public campaign strategy to ensure sustained adoption of household drinking water treatment methods. Suggestions for further studies are: (1) Sustainability of adoption of water treatme

Selective monobenzoylation of 1, 2-diols in water

Author: Mwenda, Julius William

Awarding University: Kenyatta University, Kenya

Level : MSc

Year: 2011

Holding Libraries: Kenyatta University Moi Library ;

Subject Terms: Water treatment ;

Abstract:

Protection of functional groups plays an important role in multistep organic synthesis. In many preparations of delicate organic compounds, some specific parts of their molecules cannot survive the reagents deployed or chemical environments of different reactions. Thus, these parts or groups must be protected. In this work, selective protection of 1,2-diols was achieved in water as a solvent by using a commonly known water-stable coupling reagent, 4- (4,6- dimethoxy -1,3, 5- triazin -2-yl) -4 -methylmorpholinium chloride (DMTMM), as a coupling reagent in the presence of a catalytic amount of 4-dimethylaminopyridine (DMAP) with good to excellent results. Various catalysts were initially screened, with dialkyltin catalysts being found most suitable for this process. In addition, a series of bases were evaluated, and weak inorganic bases such as K2C03, CS2C03 and Na2C03 emerged as the best for the reaction For selective monoprotection by benzoylation, benzoyl chloride or benzoic acid was alternatively used; The study also surveyed various benzoyl chloride derivatives with electron-withdrawing and electron-donating groups at meta, para and ortho positions as alternative reagents for selective monoprotection of 1,2-diols with benzoyl chloride derivatives with substituent at meta and para positions emerging as excellent protecting groups. Other protections groups like 2-thenoyl chloride and phenyl acetyl chloride have been surveyed. The work was concluded with the method being successfully applied to selectively benzoylate some symmetric or asymmetric cyclic and acyclic 1,2-diol and 1,3-diols. The structures of different monobenzoylated compounds were elucidated by proton and carbon nuclear magnetic resonance (NMR), infra red (IR) spectroscopy and mass spectrometry (MS).

Effect of enhanced coagulation with Calcium Hypochlorite on an Algae Laden Drinking Water Supply

Author: Mawia, Alex Manthi

Awarding University: University of Nairobi, Kenya

Level : MSc

Year: 2011

Holding Libraries: University of Nairobi Jomo Kenyatta Memorial Library ;

Subject Terms: Water treatment ; Algae ; Chlorine ; Calcium hypochlorite ;

Abstract:

Algae laden water is difficult to treat since it significantly impacts on finished water quality and treatment plant operations. The primary treatment plant operation issues are encountered in sedimentation since gravitational forces are largely ineffective due to algae instability and filtration processes due to increased filter clogging from algae carryover from sedimentation stage. The primary finished water quality issues are related to taste and odour and disinfection by-products (DBPs) resulting from disinfection. This research study investigates the effectiveness of pre-chlorination (enhanced coagulation with chlorination using calcium hypochlorite solution) on the removal of algae and algaederived organic matter and its influence on the coagulation and flocculation processes of water treatment. Batch bench-scale experiments were carried out in the laboratory using algae laden water samples of predominantly blue-green algae collected from a river and cultured in an open pond to peak algal concentration. The experiments were carried out for varying algal concentrations measured through chlorophyll tests using a spectrophotometer and recorded as chlorophyll-a. Break-point chlorination tests using calcium hypochlorite were carried out to determine chlorine demand before a series of jar tests with and without chlorination were carried out to determine the optimum coagulant dose. The chlorine dose used for chlorination was equivalent to chlorine demand of each sample used. Algae was found to significantly impact on the physical and chemical properties of water by increasing colour and turbidity, cause drop in pH, decrease in water hardness and increase in alkalinity. Algae was also found to cause an increase in chlorine demand. Experiments showed that pre-chlorination using calcium hypochlorite improves coagulation and flocculation processes and enhances algal removal through sedimentation. Coagulation without chlorination showed 74% algal (chlorophyll-a) removal, 62% colour improvement, 72% turbidity removal, 8.7% pH reduction, 13% total hardness reduction and 19% alkalinity reduction. Pre-chlorination (coagulation with chlorination using calcium hypochlorite) was observed to cause 5% saving on coagulant requirement, 90% algal (chlorophyll-a) removal, 74% colour improvement, 84% turbidity removal, 4.2% pH reduction, 18% total hardness reduction and 26% alkalinity reduction.