Design and Performance Evaluation of a Waste Treatment Plant
Chapter One
Objectives of the study
The main objective of the study is to carry out a design and performance evaluation of a waste treatment plant.
The Specific objectives of this research therefore are as follows:
- To design a waste water treatment plant.
- To access the proposed water treatment plant processes and the predominant maintenance culture.
- To assess the pump efficiency and performance indicators of the proposed water treatment plant.
- To determine the plant’s operational efficiency in terms of staff, quality of treated water and rate of leakages and causes.
CHAPTER TWO
LITERATURE REVIEW
Concept of wastewater
Wastewater is any water that has been contaminated by human use. Wastewater is “used water from any combination of domestic, industrial, commercial or agricultural activities, surface runoff or stormwater, and any sewer inflow or sewer infiltration”. Therefore, wastewater is a byproduct of domestic, industrial, commercial or agricultural activities. The characteristics of wastewater vary depending on the source. Types of wastewater include: domestic wastewater from households, municipal wastewater from communities (also called sewage) and industrial wastewater. Wastewater can contain physical, chemical and biological pollutants.
Households may produce wastewater from flush toilets, sinks, dishwashers, washing machines, bath tubs, and showers. Households that use dry toilets produce less wastewater than those that use flush toilets.
Wastewater may be conveyed in a sanitary sewer that conveys only sewage. Alternatively, wastewater can be transported in a combined sewer that conveys both stormwater runoff and sewage, and possibly also industrial wastewater. After treatment at a wastewater treatment plant, treated wastewater (also called effluent) is discharged to a receiving water body. The terms “wastewater reuse” and “water reclamation” apply if the treated waste is used for another purpose. Wastewater that is discharged to the environment without suitable treatment can cause water pollution.
In developing countries and in rural areas with low population densities, wastewater is often treated by various on-site sanitation systems and not conveyed in sewers. These systems include septic tanks connected to drain fields, on-site sewage systems (OSS), vermifilter systems and many more.
Wastewater treatment and treatment methods in Nigeria
The aim of treatment is to reduce the level of pollutants in the wastewater before reuse or disposal into the environment (UN Water, 2014). The standard of treatment required for domestic wastewater is usually location and use-specific. There are different wastewater treatment methods available, these methods can be simply grouped as aerobic (biological), anaerobic (biological) and physico-chemical processes.
Aerobic Treatment of Wastewater
In aerobic wastewater treatment systems, aerobic organisms in the presence of oxygen convert organic matter in wastewater into carbon dioxide and new biomass. The Oklahoma Department of Environmental Quality in explaining aerobic treatment explains the use of air for wastewater treatment. The wastewater treatment takes place in the aeration chamber. Air is blown through the sewage to allow the natural bacteria to thrive. These bacteria feed on the organic matter in the wastewater and break it down. The wastewater then flows to the clarifier where the solids are separated from the liquids. In a similar statement, Gustafson, Anderson, and Christopherson (2001) said that aerobic treatment pretreats wastewater by adding air to break down organics, reduce pathogens, and convert nutrients. Compared to conventional septic tanks, aerobic treatment breaks down organic substances more efficiently, organic solids break down faster and the concentration of pathogens in the wastewater is reduced.
Anaerobic Treatment of Wastewater
Wright (2008) and Jhansi and Mishra (2013) described the anaerobic treatment method as a process in which anaerobic bacteria break down organic materials in the absence of oxygen and produce methane and carbon dioxide. The methane produced can be reused as an alternative energy source (biogas). Anaerobic wastewater treatment is different from traditional aerobic treatment. The absence of oxygen leads to a controlled conversion of complex organic pollutants, mainly into carbon dioxide and methane. Anaerobic treatment has beneficial effects such as the removal of higher organic load, low sludge production, high removal of pathogens, biogas production and low energy consumption (Mrowiec and Suschka, 2009).
Physico-Chemical Treatment of Wastewater
Physicochemical wastewater treatment is a frequently used technique in the area of wastewater treatment. Physicochemical wastewater treatment techniques are applied for the removal of heavy metals, oils and greases, suspended matter and dissolved organic substances, organic and inorganic components, difficult to decompose, toxic pollutants or high salt concentrations, phosphorus and so on. The physicochemical wastewater treatment techniques are used as pre-treatment, final treatment as well as specific treatment for wastewater reuse as process water. Dhameja (2006) included dilution, sedimentation and filtration as being part of the physical processes. According to Cruden (2015) Physicochemical treatment of wastewater focuses primarily on the separation of colloidal particles. This is achieved through the addition of chemicals (called coagulants and flocculants). This changes the physical state of the colloids allowing them to remain in an indefinitely stable form and therefore form into particles or flocs with settling properties. In addition to the processes stated by Dhameja (2006), Cruden (2015) further added coagulation (rapid mixing) and flocculation as physico-chemical process.
General Concept of Treatment Plant Assessment
Treatment plant assessment is the process of evaluating the efficiency, capacity, performance, reliability and effectiveness in meeting the objectives of a treatment plant. Assessment takes place whenever people or group of people evaluate the quality or level of performance of a treatment plant, in fundamental nature, assessment attempts to determine whether specific objectives have been accomplished or not, therefore, qualitative and quantitative judgments are made about a project or treatment plant. The judgments are based on testing devices like oral interview, on site measurement of desire parameters. Assessment completes the overview of treatment cycle of forecasting, policy formulation, planning, implementation, control and monitoring.
Treatment Plant Operation
Treatment plant operation focuses on the physical system and its engineering aspects, it is the immediate or direct consequences of treatment plant, it is an efficient level, and input and systems outcomes are under the control of the engineer. The immediate concern here is for the physical status and functioning of water supply projects and sanitation schemes, which can be assessed in terms of accessibility, quality, quantity and reliability. These factors can be assessed in straight forward physical unit (Gray, 1996).
CHAPTER THREE
PROPOSED METHODOLOGY
Materials
The materials used for this research are:
- Treated water sample obtained from the proposed water treatment plant for quality test.
- A questionnaire will be used to assess the plant performance culture
Some of the equipment that will be used in this research include: Micrometer screw gauge, Stop Watch, Bucket, gallons and vehicle.
Method
To assess the design and performance evaluation of a waste treatment plant, the various sections of the treatment plant will be examined through the following methods:
- Surveying methods, by visual inspection, in-depth interviews and structured questionnaires.
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