Water is critical to population for a social, economic activities and the entire existence (Kiwanuka, S.N., et al, 2015). Without having access to safe water, is a form of deprivation that threatens life, destroys opportunity and undermines human dignity (Watkins 2006). The United Nations General Assembly recognized the human right to water and sanitation. Nevertheless, access to safe water is still a challenge (Valcourt, N. et al, 2020). In Uganda, national safe water coverage is estimated at 66% with 42% coverage in rural areas (DWD 2011). The continued water supply deficit, both in Uganda and elsewhere, has been attributed to a water governance crisis (Asingwire 2008; Mugumya 2013). According to Naiga et al 2015, “In the context of recent devolution processes in Uganda, the operation and maintenance of drinking water infrastructure still pose a major challenge.”

Uganda has a very high population growth rate of 5.2% (World Bank n.d.) and this produces additional pressure on reaching United Nations Millennium Development Goal (MDG) related to providing sanitation for rural and urban populations (WHO/UNICEF 2015). The Republic of Uganda has ambitious plans of development, one of the developments requirements is safe access to water for rural and urban areas (Akoli, B.S., 2014), and this means there should be high investments in water supply and sanitation infrastructure (Dewachter, S. et al, 2018) so as to achieve the country vision (Uganda Vision 2040). On the other hand, the country is committed to UN Sustainable development goal 6 that is “Ensure availability and sustainable management of water and sanitation for all”, As a result, Uganda has to make studies about water treatment and increase of treatment efficiency that are highly required (Harvey, A. and Mukanga, J., 2020).

1.2 Problem statement

According to Kamuli Strategic plan (2016-2021) Water supply in Kamuli Municipality is far below the required capacity this is because, the Municipality’s current treatment plant produces averagely 420M³-500m³ per day against the current population of 110,000 (UBOS, 2019), which translates into 3.8 liters per person perday , this is very low amount of water on average person as compared to the UN, (2018) recommendations of 50 liters per person per day, more to that NWSC, (2018) Requires 1500m³ per day to meet a daily demand of customers for municipality of Kamuli size. The Municipality records further indicates that despite of the inadequate water, the water quality also is a major concern as there is an increased coloring of the water, presence of solid particles Implying high turbid water is being supplied, something that puzzles the technical and Engineering department of the Municipality as to what could be the cause and what could be done, in line of the above Kamuli municipality uses slow filtration process that does not satisfy the high demand from increasing population, as evidence that the current water process was designed for a town of 20,000 in 1989 and this is at the backdrop of the numerous benefits of the slow sand filter process which include advantage of low maintenance costs and high efficiency (Bagundol, T.B., et al, 2013), it’s against this Background that this study Intends to investigate into performance improvement of a water treatment plant – kamuli slow sand filters.

1.3 Research objectives

1.3.1 Main Objective

To investigate the performance of water treatment plant for possibility of its improvement.

1.3.2 Specific objective

To identify water treatment problems.
To identify short term measures to improve the quality of treated water.
To identify short term measures to increase the quantity of drinking water produced.

1.4 Research questions/hypothesis

What are the water treatment problems?
What are the short term measures to improve the quality of treated water?
What are the short term measures to increase the quantity of drinking water produced.

1.5 Research justification.

Kamuli’s objectives and vision for rural water and sanitation is to provide sustainable safe water supply and sanitation facilities within easy reach of 85% of the rural peri urban population by the year 2026 with at least 95% effective use and functionality of facilities (Kamuli District, 2020). This research would help in providing information on the required steps to help reaching this target.

1.6 Importance of the study

The purpose of the study is to have an increased amount of treated water added into the system and have a possible increase of efficiency that helps to provide population with better access to safe water and also gives more flexibility to manage and plan in face of increase in population, increase cost of supply of water and many different factors. As part of country vision, Uganda is looking to provide full access to safe water for population as part of country commitment to SDGs and this requires a lot of investment in infrastructure and this study would help reducing amount of such required investments.

1.7 Project scope

The study scope will be Kamuli treatment plant considering Kamuli municipal area coverage and other different water supply outskirts.

Chapter 2: Literature review

2.1 Filtration of Water

Water treatment has been a main challenge for humanity. As the twenty first century begins, the challenges of water treatment have become more complex and therefore several types of treatment methods were discovered (table 2.1).

Common contaminants in surface water can be sediments, nutrients: nitrogen and phosphorous, Bacteria and Viruses. Bwire, G et al (2020), conducted a study on surface and spring water used for domestic purposes between February 2015 and January 2016 in Uganda. Results showed that all sites had mean water turbidity values greater than the WHO drinking water recommended standards. Moreover, 27% of the ponds had pH and dissolved oxygen respectively outside the WHO recommended range. The study showed that such conditions are ideal for survival of Vibrio Cholerae.

One of the methods used in water treatment from surface water is filtration. Filtration defined as an interaction between a suspension and a filtering material, pollutants are removed from the solution when they become attached to the media or to previously captured particles (Hajjaj, 2011).

Using sand filtration is common for drinking water and wastewater treatment. Filtration with sand media has been used for over a century to treat water and wastewater. In 1893, first sand filter was built in America at Lawerence, Massachusetts and the filter proves to be a great success (Crittenden et al, 2012).

Table 2.1: Summary of methods used for water treatment in 20^th century.

Source: (Crittenden et al, 2012).

Anderson et al.(1985), provided guidance about how to successfully choose a filter media for sand filter to get good pollutant removal, this depends on proper choice of:

Suspended particle size.
Pore size.
Grain shape.
Filtration velocity.
Temperature of liquid.
Chemical properties of the water and particle.

The type sand to be used should be fine enough to make the biological analyses, but it had to be also coarse enough to not allow surface clogging. The sand being so coarse does not provide enough retention time for adequate biological decomposition to take place and allow to pass suspended particles. On the other hand, very fine sand limits the quantity of water filtered because of filter clogging (Mesquita et al, 2012).

2.2 Types of sand filters

There are two main types of sand filter systems used for water treatment as following:

2.2.1 Slow Sand Filter

In this type of sand filters, the filtration media is fine sand and the downward flow of the water is between 0.1 and 0.4 m³/h per m² of surface and the size of sand particles is between 0.2 to 0.4 mm (Huisman & Wood, 1974). The sand bed is put upon a layer of supporting gravel (Fig. 2.1).

Figure 2.1: Slow sand filter. Source: Huisman & Wood (1974)

According to SWMM (2019), “Slow sand filter effectively removes turbidity and pathogenic organisms through various biological, physical and chemical processes in a single treatment step and characterized by a high reliability and rather low lifecycle costs”. Moreover, neither construction nor operation and maintenance require more than basic skills. Therefore, this method is suitable for small to medium-sized, rural communities with a fairly good quality of surface water source.

2.2.2 Rapid Sand Filter

The sand used in this type is coarser than what used in slow sand filter with an effective grain size of 0.6-2.0 mm. As the space between sand particles in higher, this allows filtered water to pass with higher rate that is in the range of 5 to 15 m³/hr per square meter of surface (Huisman & Wood, 1974). In this method, there isn’t a biological filtration process and the process is primarily adsorption and some straining.

So as to keep good quality of treatment, rapid sand filter has to be cleaned frequently every 1 or 2 days. The cleaning is done using a backwash process by high-pressure water that forced upwards through the filter bed to remove accumulated solids (Huisman & Wood, 1974).

2.3 COAGULATION PROCESS

Coagulant chemicals with charges opposite those of the suspended solids are added to the water to neutralize the negative charges on non-settlable solids (such as clay and color-producing organic substances).

Once the charge is neutralized, the small suspended particles are capable of sticking together. These slightly larger particles are called microflocs, and are not visible to the naked eye. Water surrounding the newly formed microflocs should be clear. If not, coagulation and some of the particles charge have not been neutralized. More coagulant chemicals may need to be added.

A high-energy, rapid-mix to properly disperse coagulant and promote particle collisions is needed to achieve good coagulation. Over-mixing does not affect coagulation, but insufficient mixing will leave this step incomplete. Contact time in the rapid-mix chamber is typically 1 to 3 minutes.

Flocculation

Flocculation, a gentle mixing stage, increases the particle size from submicroscopic microfloc to visible suspended particles. Microfloc particles collide, causing them to bond to produce larger, visible flocs called pinflocs. Floc size continues to build with additional collisions and interaction with added inorganic polymers (coagulant) or organic polymers. Macroflocs are formed and high molecular weight polymers, called coagulant aids, may be added to help bridge, bind, and strengthen the floc, add weight, and increase settling rate. Once floc has reached it optimum size and strength, water is ready for sedimentation.

Design contact times for flocculation range from 15 or 20 minutes to an hour or more, and flocculation requires careful attention to the mixing velocity and amount of mix energy. To prevent floc from tearing apart or shearing, the mixing velocity and energy are usually tapered off as the size of floc increases. Once flocs are torn apart, it is difficult to get them to reform to their optimum size and strength. The amount of operator control available in flocculation is highly dependent upon the type and design of the equipment.

Conventional plants separate coagulation (or rapid-mix) stage from flocculation (or slow-mix) stage. These stages are followed by sedimentation, and then filtration. Plants designed for direct filtration route water directly from flocculation to filtration. These systems typically have a higher raw-water quality. Conventional plants can have adjustable mixing speeds in both the rapid-mix and slow-mix equipment. Multiple feed points for coagulants, polymers, flocculants, and other chemicals can be provided and there is generally enough space to separate the feed points for incompatible chemicals.

Conventional plants have conservative retention times and rise rates. This usually results in requirements for large process basins and a large amount of land for the plant site. On-site pilot plant evaluation, by a qualified engineer familiar with the water quality, is recommended prior to design.

3.1.2 Kamuli Water Treatment Plant:

National water and sewerage corporation (NWSC) took over the infrastructure from the Kamuli local government to supply water mainly in the municipality areas but major infrastructure like Raw water intake pump house, water reservoirs and the treatment plant were constructed and previously was managed and operated by private operators who later on handed over the facilities to the local government before NWSC would take over from them in the year 2014.

According to NWSC, the water supply in Kamuli municipality is so intermittent. In this municipality (Kamuli), there is a water treatment plant that uses slow sand filters but has a lot of limitations as more hours is spent in production comparing to little time spent in the supply i.e. it takes averagely 10 hours to fill the 2 water reservoirs of 180 cubic and 120 cubic at different time intervals.

Figure 3.2: Aerators and the two reservoirs behind of 180 m³ (concrete) and 120 m³ (steel).

Apart from the surface water from the catchment dam, the Kamuli municipality also has a supply boost from the very low yielding four (4) production boreholes with the minimum yield of 4 m³/hour and maximum yield of 8m³/hour. According to NWSC, the daily demand for this municipality is approximated to over 1500 m³/day but they are only able to produce between 420-500 m³/day.

A lot of water could actually be abstracted from the Namalemba catchment dam as this was observed with the two motor pumps at intake to be pumping averagely 120 m³/hour but it’s not sustainable due to the overflows at the Aerators (Fig. 3.4) and the slow sand filters after a very short time which calls for isolation at certain intervals to regulate these overflows. Therefore, a small pump is always engaged so that the there is a prolonged pumping without overflows.

There are three small filter units of 3.2×4.2×4.5 meters’ dimension with the in-let pipe diameter of OD110 mm connected after the small aerator system and later on discharges the filtered water to the underground contact tank for disinfection (chlorination) before being uplifted to the overhead reservoirs to be supplied to the community by gravity (Fig 3.3). These slow sand filter units have been closely monitored and recorded to be filtering only averagely 30 m³/hour to the contact tank which is far less than required to have much water produced and supplied to the customers.

Figure 3.3: Schematic Plan of Kamuli Treatment Plan

Figure 3.4: Aeration cascade that receives raw water from the intake, subject to aeration process and proceeds to the slow sand filters at Kamuli treatment plant.

The performance of these slow sand filters drastically deteriorates during rainy season when the turbidity goes so high due to runoffs to the catchment dam especially after the heavy down pour (rain) as we hardly attain the 30 m³ in approximately two hours.

Figure 3.5: Slow sand filter units and the pump house together with chemical dozing house at Kamuli treatment plant

Chapter 3: Methodology

3.1 Study Area:

Data collection and analysis Objective	Method	Output
Water treatment problems	PH Test PH is one of the most common water quality tests performed. PH indicates the sample’s acidity but is actually a measurement of the potential activity of hydrogen ions (H⁺) in the sample. PH measurements run on a scale from 0 to 14, with 7.0 considered neutral. Solutions with a pH below 7.0 are considered acids The following steps for PH Test will be carried out. i. Getting a clean container ii. Filling it up with test water iii. Making sure the water is deep enough iv. Getting a litmus paper v. Dipping a litmus paper test strip into the container vi. Litmus paper will either be red or blue As blue litmus paper turns red under acidic conditions, and red litmus paper turns blue under basic or alkaline conditions, with the color change occurring over the pH range 4.5–8.3 at 25 °C (77 °F). Neutral litmus paper is purple	This will enable in determining the level of Acidity of water in order to evaluate if its fit enough for consumption
	Turbidity test for water. A Standard formazine solution of Nephelometric Turbidity Units (NTU), will be placed on Tubidimeter in the path of rays and scale is brought 9 n.t.u. The Water sample is taken in a test and is placed in Turbidimeter. Use A Cell rise if the turbidity is more than 100 N.T.U and get the turbidity dilution factor. Turbidity meters utilize a light and photo detector to measure light scatter, and read out in units of turbidity, such as nephelometric turbidity units (NTU) or formazin turbidity units (FTU).	Measure of Coagulation
	Salinity is the measure of the amount of dissolved salts in water. The study will use two ways to determine salinity of water. One method will be boiling. This method will involve. -Saucepan -Astove -test water In this method the water sample will be collected and put in the sauce pan then heated up to 100⁰C. After constant heating of the water until all the water has evaporated the amount of salt left will be determined to examine the level of salinity of the water being Tested. Another Method will by use of electrical conductivity. A conductivity meter measures the amount of electrical charge an aqueous solution can carry, or conduct. Pure water is a poor conductor of electricity, but when ions are dissolved in the water the ability to pass a current increases. The conductivity meter uses a probe to measure conductivity of a solution. Depending on the concentration of ions in the solution, the conductance is either high or low, which results in a fast or slow current reading. The relationship between ions in water and conductivity is predictable and so we can use precise instruments estimate ‘salinity’ by measuring conductivity.	Testing of salinity water
	Dissolved oxygen Total suspendend solids Bacteria test

Measures to improve the quality of treated water

METHOD
Chlorination	Through the use of Shock chlorination. A strong chlorine solution is added into a well or pumped through the plumbing system to kill microorganisms on a one-time basis. This is used when the well is constructed, repaired, or a new pump is installed to kill bacteria that may be present on the pipes or installation equipment. This will be used to Kill bacteria in the water to ensure water quality.	Water is purified free from Bacteria
Distillation process	Steps · Water is heated in a boiling chamber · Water evaporates and steam is produced · Steam leaves the boiling chamber · Steam condenses · Remaining contaminants are removed · Water collects in a storage container.	Cleans water ready for drinking
Coagulation Introdn of coagulants Sedimentation

3.2 Data collection

This study requires a set of essential data to address the current treatment system performance, the following shows data needed with official source of data:

3.2.1 Climatic Data: The official source of climate data in Uganda is Uganda National Meteorological Authority; it is responsible for climate data such as rainfall data, temperature data, wind data and humidity data.

This data will be obtained from the National Meteorological Authority since this will be very useful to consider periods of the year at which rainy seasons are defined where water with high turbidity reaches the treatment plant.

3.2.2 Water Demand Data: This data will be obtained from National Water and Sewerage Corporation (NWSC) or Ministry of Water and Environment for areas already supplied by NWSC and for other areas it can be computed with average consumption per day.

3.2.3 Supply Data: This data will be obtained from National Water and Sewerage Corporation (NWSC) or Ministry of Water and Environment and also field visits of different supply categories will be done.

3.2.4 Water Quality Data: It will be done by taking samples from the treatment plant and test them at the central laboratory. The tests suggested are PH, TDS, TSS, Color, turbidity, Chlorine residue and e-coli bacteria test.

3.3 Approaches and Study Workflow Methodology

The following shows main topics planned to be discussed in content of thesis.

Literature review of past studies if any.
Analyze water supply problems in Kamuli treatment plant: this includes drawing the hydraulic scheme of the treatment plant to see the relation between production that represents the supply side and the demand of the population. Also supply from the Dam can be addressed through field study by carrying out measurement at the dam and its outlets to determine the flow rate.
Analyze water quality problems associated to Kamuli treatment plant: this includes making water quality tests on different phases that is before the treatment plant, after treatment plant, along the networks spots and at some of the customers’ premises to have a full vision of the quality problems.
Project Water demand: this includes calculations using Excel of population increase and targeted increase in water production for next 10 years.
Build different scenarios for changes that may take place in Kamuli treatment plant such as adding more aerations tanks, sand filters or using new filtering technology to accelerate production.
Conclusion and recommendations

To achieve the objectives of the study a continuous coordination to be considered with different project stakeholders. The analysis and the proposed solution to be in consistent with the district plan of access to water. The following diagram shows the methodology flowchart. (Fig. 3.6)

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