Development of black coating on filtering media and its effect on filter performance at Kpong headworks of Ghana

Kpong water Treatment plant is one of the two major Water treatment plants supplying the Accra/ Tema Metropolitan areas. The filtering media at Kpong water works has been observed to develop a black coating after three to four years of commissioning. This appearance results in more water than necessary being used for backwashing the filters. The source and toxicity of the black coating material as well as the possibility of it leaching into the treated water have not been determined. The main objective of this study was to characterize and investigate the development of black coating on the Kpong filtering media and its effect on the filter performance. Another focus of the study was to conduct water quality analysis of effluents from the riparian industries, and the raw water at strategic points within the study area in order to trace the source of the black coating material. The effect of the black coating on filter performance with respect to iron removal was investigated using a laboratory based batch reactor. The study showed the chemical components of the black coating of the Kpong filter media to be mainly iron, manganese, sulphates and sulphides. Other components like copper, lead, mercury occurred in trace concentrations. The blackening of the filter media at Kpong is probably due to occurrence of iron sulphates and sulphides, hydroxides and / oxides of iron and manganese ions in the raw water. The black coating has a limiting effect on the iron removal capacity of the coated (Kpong) filter media. The adsorption phenomenon on the coated media of the Volta River Authority and the fresh filter media was mainly chemisorption.Keywords: Filter media, black coating, filter performance, iro

Defluorination of drinking water using surfactant modified zeolites

The prevalence of high concentrations of fluoride (i.e. > 1.5 mg/l) in groundwater in the Northernpart of Ghana especially around the Bongo communities has been an issue of concern.Owingto the arid nature of these localities, the inhabitants (who are mainly peasant farmers), relymore on groundwater sources for their drinking water. With the strenuous nature of their joband the warm weather conditions, the farmers generally consume more water, thus becomingmore vulnerable to dental and skeletal fluorosis. This study focused on the removal of fluoridefrom groundwater by employing surfactant modified zeolites (SMZ) synthesized using locallyavailable kaolin material as precursor. The zeolite synthesis involved calcination of kaolin, alkaline fusion and hydrothermal treatment. The final product was modified with 5g/L Hexadecyltrimethylammonium bromide (HDTMABr). The zeolite was characterised by Xray Diffraction(XRD), Energy Dispersive Xray (EDX) and Scanning Electron Microscopy (SEM) and the modified form employed in batch fluoride removal studies. The fluoride adsorption kinetics was studiedusing model water with varying initial fluoride concentration. From the EDX analysis, the synthesized zeolite NaLSX was found to comprise predominantly Oxygen (60%), Silicon (15%), and Aluminium (13%). The SEM showed the zeolite NaLSX crystals to be octahedrally shaped. The unmodified zeolite NaLSX was incapable of adsorbing fluoride ions but the surfactant modified zeolite adsorbed fluoride. The fluoride adsorption capacity of the modified zeolite was pH dependent and peaked at pH 6.0 – 7.0. Keywords: characterization, defluoridation, groundwater, surfactant, zeolite

Evaluating Access to Potable Water and Basic Sanitation in Ghana's Largest Urban Slum Community: Old Fadama, Accra

Access to potable water and basic sanitation in urban poor communities remains a critical issue in the developing world. This paper examines access to potable water and basic sanitation in Ghana's largest urban slum and the level of commitment by stakeholders to improve the current conditions. It drew on an extensive field survey, interviews, focus group discussions and drinking water quality analyses. The study revealed that the community depend entirely on vended water for their daily water supply needs. Apart from being sold at exorbitant prices, the sources of drinking water is also contaminated with attendant health risks. Household toilets are non-existent in the community and thus residents rely exclusively on public latrines; KVIP and pan latrines which are also inadequate. This partly accounts for the practice of open defecation in the community with possible health effects such as diarrhea and cholera. Indiscriminate dumping of refuse, choked drains and pools of stagnant water are ubiquitous thereby posing health threats. There is a low level of commitment to improving access to water and sanitation in the community by major stakeholders in spite of the glaring health effects. The outcomes of this study will be useful to relevant stakeholders and authorities in developing suitable strategies for improving access to water and sanitation for urban poor communities. Keywords: Accra, health, Old Fadama, sanitation, slum, wate

Effect of crystallization time on the hydrothermal synthesis of zeolites from kaolin and bauxite

Kaolin and bauxite were used as alumina and silica sources to synthesize zeolites hydrothermally. The source mate-rials as well as the synthesized zeolites were characterized by X-ray diffraction (XRD) scanning electron microscopy (SEM), en-ergy dispersive x-ray analysis (EDX) and Fourier transformed infrared spectroscopy (FTIR). XRD spectra of the bauxite showed Gibbsite phase whereas that of kaolin gave 32.4 % quartz and 67.6 %. The main phases of zeolites obtained after hydrothermal crystallizations were zeolite types LTA, analcime and zeolite X. Longer crystallization time resulted in phase change of the zeo-lites into sodalite. Hence, natural raw materials such as bauxite and kaolin have the attractive features of providing the staring reagents for the synthesis of ultrapure synthetic zeolites

Adsorptive removal of manganese, arsenic and iron from groundwater; Dissertation, Wageningen University and UNESCO-IHE Institute for Water Education, Delft.

Arsenic, manganese and iron in drinking water at concentrations exceeding recommended guideline values pose health risks and aesthetic defects. Batch and pilot experiments on manganese adsorption equilibrium and kinetics using iron-oxide coated sand (IOCS), Aquamandix and other media have been investigated and modeled. Effect of manganese and iron loading on manganese removal and rate of oxidation of adsorbed iron and manganese have been studied. Aquamandix and IOCS demonstrated iron and manganese adsorption capacity that increases with increasing pH under oxic and anoxic conditions. Manganese loading and low filtration rate using feedwater with no nitrite favour non-uniform development of catalytic manganese oxide on media that subsequently enhances manganese removal

Adsorptive removal of manganese, arsenic and iron from groundwater

To determine the scale of the problem of arsenic, iron and manganese contamination of groundwater in Ghana a survey was performed in the first phase of the research to provide in depth information with respect to these contaminants. Presence of these mentioned contaminants in groundwater is not peculiar to Ghana alone. Many countries in the world have similar problems with their groundwater. Establishing the existence of the problem also calls for the need to find remedies. Over the years much studies have been done in the Unesco-ihe on the adsorptive mechanisms and techniques for iron and arsenic removal from groundwater. Therefore in this study much emphasis is placed on the adsorptive removal of manganese from groundwater. This research has the following as it objectives: 1. The conduction of a survey for the arsenic, iron and manganese content in selected groundwater aquifers in Ghana. 2. Determination of the arsenic, manganese and iron adsorption capacities of different locally available filter media. 3. Determination of the effect of pH on adsorption capacities of the selected media for arsenic, manganese and iron. To determine the effect of iron (II), manganese (II) presence on arsenic adsorption capacity of selected media – (competition). 4. Studies on the rate of oxidation of Fe (II) and Mn (II) adsorbed onto one or more selected media under different conditions (e.g. dissolved oxygen, pH etc.). 5. Determination of the rate of adsorption of Mn (II) onto one or more selected media under different oxic conditions. 6. To develop a conceptual model that describes the processes involved in adsorptive arsenic, manganese and iron removal. To investigate to what extent these processes can be described in a quantitative way with one or more mathematical models . Generally the study has the following relevance: 1. Provide a base line data on the arsenic and manganese content of selected groundwater aquifers in Ghana. 2. Provide information on the adsorption capacities of locally available filter media for manganese. 3. Contribute to the knowledge on the kinetics and mechanisms of catalytic adsorptive iron, manganese removal. 4. Provide an efficient backwashing procedure for regeneration of adsorptive sites in iron-oxide coated filters operating in the oxidative adsorption mode