ASSESSMENT OF THE PERFORMANCE OF WASTE STABILIZATION POND AT THE CAPE COAST TEACHING HOSPITAL IN GHANA

ABSTRACT

In developing countries, hospital wastewater management is an issue of major concern. The purpose of the study was to evaluate the performance of the waste stabilization pond at the Cape Coast Teaching Hospital in Ghana. Wastewater samples were taken from the raw sewage (anaerobic pond) after screening. The process was repeated in both the facultative and maturation ponds, sequentially. Fifty four samples representing 18 samples each from the three stages of the waste stabilization treatment were analysed to evaluate the efficiency of the ponds over a period of six months. The selected parameters were analysed based on a well-established protocols. Descriptive and inferential statistics were used to determine the distribution and relationships among wastewater parameters measured in the stabilization ponds. The results showed that the final effluent values obtained for most of the parameters were within the acceptable limits of the Ghana Environmental Protection Agency. However, conductivity, TSS, turbidity, nitrate, phosphorus, magnesium and mercury levels were not compliant. The efficiency of the WSP for turbidity was 56.78%, TSS 71.96%, BOD 64.78%, magnesium 3.55%, total coliforms 34.48%, E.coli 53.53%, Iron 50.60%, manganese 75.40%, and cadmium 47.83%. The rest of the parameters exhibited negative values. Based on the low efficiency removal of some of the parameters, the effluent should be treated to prevent any possible pollution in the environment.

CHAPTER ONE

INTRODUCTION

This chapter presents an overview of the thesis in terms of the background to the study and the statement of the research problem. The purpose and objectives of the study followed by the hypotheses that were formulated to guide this thesis are part of the chapter. This chapter also presents the significance of conducting the research work as well as the scope of the research work.

Background to the Study

Urbanization and rapid industrialization in many cities throughout the world have occurred as a result of an increase in human population. This situation has led to an increase in the discharge of domestic and industrial as well as hospital effluents into receiving water bodies (Massoud, Chami, Al-Hindi, & Alameddine, 2016). Wastewater released sometimes contain all sorts of chemical and biological pollutants which include nitrogen, phosphorus, heavy metals, detergents, pesticides, hydrocarbons, viruses, bacteria and protozoa. Chemicals such as heavy metals (Cd, Cr, Cu, Pb, Hg, Zn and Fe), metalloids (As) and biological pollutants if not treated properly may cause deleterious effects on organisms and the environment (Mansouri & Ebrahimpour, 2011; Akpor & Muchie, 2011; Nziku & Namkinga, 2013; Armah & Gyeabour, 2013; Armah, Quansah, & Luginaah, 2014). Heavy metals such as cadmium, chromium, copper, lead mercury, nickel, selenium, silver and zinc are toxic to wastewater treatment systems (Wissenschaftszentrum, 2005). These heavy metals are toxic to humans and other organisms, which may end up in surface water where they may influence the aquatic ecosystem and interfere with the food chain. Humans are particularly exposed to the drinking water, produced from surface water (Pauwels & Verstraete, 2006).

Wastewater from hospitals may constitute environmental potential contamination hazard due to chemical and microbiological characteristics of the effluent (Bohdziewicz & Sroka, 2005). According to Steven, Matt, & Rai (2008), wastewater effluents when released directly into the environment are responsible for the degradation of natural ecosystems and impacts may arise from an increase in nutrient loads leading to eutrophication, decreased levels of dissolved oxygen and releases of toxic substances, many of which can bioaccumulate and biomagnify in aquatic organisms (Morrison, Fatoki, Persson & Ekberg, 2001).

Currently, there are several techniques used to treat wastewater. These can be classified into two groups: conventional and non-conventional treatment techniques. The former has high-energy requirements whilst the latter is solely dependent on natural purification processes.

The conventional systems of wastewater treatment include trickling filters, activated sludge systems, bio-disc rotators and aerated lagoons. On the other hand, non-conventional systems, which are also called eco-technologies include constructed wetlands and waste stabilization ponds, WSPs (Nhapi & Gijzen, 2005). Out of the several technologies available, the recommended type for developing countries is the WSPs (Awuah, 2006). Several conventional wastewater management practices are not effective in the complete removal of antibiotics (Brown, 2011).

WSPs are biological treatment systems in which processes and operations are highly dependent on the environmental factors such as temperature, wind speed and light intensity that are highly variable and any given combination of these environmental parameters is usually unique to a given location (Gray, 2004).

WSPs are commonly used as efficient means of wastewater treatment relying on little technology and minimal regular maintenance. They generally consist of a series of ponds usually between 1 and 3m deep depending on the type of pond (Toumi, Nejmeddine, & Hamouri, 2000), namely anaerobic, facultative and maturation pond. The use of WSP in domestic applications is about 100 to 200 L per person per day, but the quantity for hospitals ranges from 400 to 1200 L per day per bed (Emmanuel, Perrodin, Keck, Blanchard, & Vermande, 2005).

Hospital wastewater normally contains several organic substances that are resistant to biological degradation and attended by low biodegradability ratio of biochemical oxygen demand (BOD5) to chemical oxygen demand (COD) of 0.3, which shows a resistance toward conventional activated sludge biological treatment process (Kajitvichyanukul & Suntronvipart, 2006; Polar, 2007).

Studies have shown that the release of wastewater from hospitals is associated with an increase in the prevalence of antibiotic resistance (Elmanama, Elkichaoui, & Mohsen, 2006). Exposure even to low concentrations over long periods of time may result in selection and consequent spread of resistance to pharmaceuticals.

The general wastewater treatment methods depend on biological processes, principally bacteria feeding on organic material in the wastewater and most wastewater treatment plants are designed to remove biodegradable organic material, but not even low concentrations of synthetic pollutants (Karin, 2005). A study conducted in Thailand on hospitals where activated sludge and oxidation ditch were used, bacteria load exceed standard levels; pathogenic bacteria and parasites were found in two-thirds of the hospitals and heavy metals, namely lead, chromium and cadmium were also found in hospital effluents within an acceptable range (Danchaivijitr, Wongchanapai, Assanasen, & Jintanothaitavorn, 2005). A study conducted in Iran on seven hospitals revealed that activated sludge process, that is, secondary treatment was not effective in treating hospital wastewater (Mesdaghinia, Naddafi, Nabizadeh, Saeedi, & Zamanzadeh, 2009).

Waste stabilization ponds are the most important method of wastewater treatment in developing countries where sufficient land is normally available and where temperature is most favourable for their operation (Mara, 2003). If properly designed and operated, waste stabilization ponds (WSPs) can attain a 99.9% faecal coliform reduction and are capable of attaining l00% removal of helminths (USEPA, 2007). They are arranged in a series of anaerobic ponds, facultative pond and finally one or more maturation ponds, where anaerobic and facultative ponds are designed for BOD removal and maturation ponds are designed for faecal bacterial removal (Mara, 2003).

Some studies have been carried out in Ethiopia on solid waste management in hospitals but little or no previous data is available on wastewater.

It is, therefore, difficult to estimate the damage that wastewater from hospital has inflicted on human health and the environment. More so, observations indicate that, most health facilities have not put in place an organized management system to address Health Care Waste Management (HCWM) properly and where such a system was present, it did not meet the minimum requirements (Federal Ministry of Health, 2008).

Waste stabilization ponds have been used successfully and widely to treat municipal wastewater (Mara, 2003). Although the quality of hospital wastewater is similar to municipal wastewater, wastewater effluent from hospitals may contain non-metabolized pharmaceutical compounds, antibiotics, disinfectants, anaesthetics, radioactive elements, X-ray contrast agents and other persistent and dangerous compounds (Boillot, 2008; Carballa et al., 2004; Jolibois & Guerbet, 2005).

Statement of the Problem

Hospitals consume large volumes of water every day. The consumption of domestic water on the average is 100L per person per day, while that of hospitals varies from 400 to 1200L per bed per day (Dehghani & Azam, 2008) and this generates significant amounts of wastewater loaded with microorganisms, heavy metals, toxic chemicals, and radioactive elements. Such waste effluents could endanger public health and welfare if they are discharged into water bodies without treatment (Amouei et al., 2015). Wastewater could bring about skin diseases or enteric illnesses if it is not treated well before discharge into the environment. So far studies on the treatment of hospital wastewater by WSPs and their ability to remove various pollutants and pathogens are rather scanty especially in developing countries such as Ghana. Few experimental studies have focused on the full range of biological and chemical contaminants and their interactions in hospital wastewater. Majority of these experimental studies, the compounds analysed in wastewater were not necessarily the most important ones in terms of toxicity or impact on the environment and human health. This gap in the literature is a fundamental motivation for this thesis.

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Item Type: Ghanaian Topic  |  Size: 143 pages  |  Chapters: 1-5

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