Investigating the purification of drinking water using xylem from coniferous tree

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Mr. Muwanguzi Jonathan*, Ms. Akua Oscol, Ms. Namulindwa Prosy

Muwanguzi Jonathan is a graduate with a BEng. Civil Engineering from Ndejje University. For his undergraduate studies, he did research on the purification of drinking water using xylem from coniferous trees.

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The use of xylem filters to filter groundwater against biological pathogens is an attractive alternative to reduce the cost of purification of water and the adverse effects that come along with its ingestion. Taking the case of Ndejje village homesteads located in Nyimbwa sub county Luweero district, a supplementary technology in providing safe water to drink was investigated and research conducted to analyze the effectiveness of the xylem filters, here water samples from a given well were collected, filtered using xylem tissue, test before and after in Ndejje university water resource laboratory.  Parameters tested included Dissolved Oxygen (D.O), Total Coliform, E-Coli and Total Suspended Solids (TSS), and Iron. These results were compared to the WHO quality guidelines and the UNBS water quality standards. 

Keywords: Disinfection, Filtration, Membrane materials, UV disinfection, Xylem filtration

1.0         INTRODUCTION

The world health organization (WHO) reports that 1.6 million people die every year from diarrhea disease attributed to a lack of access to safe drinking water with 90% of children under the age of five mostly in developing countries (Bain et al., 2012).  More than one barrier which includes prevention of infection, sanitation, and disinfection is important to correctly prevent the spread of waterborne illnesses. However, if only one barrier is viable, it has to be disinfection until proof exists that chemical contaminants are in greater danger than the hazard from the ingestion of microbial pathogens. This indicates; controlling water class on the factor of use is important and frequent only due to the problems of microbial regrowth. This comes by way of products of disinfectants, Pipeline corrosion, and Infection inside the distribution device

There are common technologies for water disinfection against disease-causing pathogens including filtration, UV disinfection, boiling, treatment with ozone, and Chlorine treatment. Chlorine treatment is effective on a large scale but becomes expensive for smaller towns and villages (Zyara, Torvinen, Veijalainen, and Heinonen-Tanski, 2016). Boiling is an effective method to disinfect water however, the ozone treatment amount of fuel required to disinfect water by boiling is several times more than what a typical family will use for cooking. UV disinfection is a promising point-of-use technology available, yet it does require access to electricity and some maintenance of the UV lamp, or sufficient sunlight. Small and inexpensive filtration devices can potentially address the issue of point-of-use disinfection (Anon, 1990. Seminars on identification and treatment of waterborne diseases in water supplies,)

An ideal technology does not currently exist. Also, carbon-based filters are not effective at removing pathogens and can be used only when the water is already biologically safe (Zyara, Torvinen, Veijalainen, and Heinonen-Tanski, 2016). They suffer from high costs, fouling (this is the forming of h2O2 membrane and often require pumping power due to low flow rates that prevent their wide implementation in developing countries). In this context, new tactics and proposals, and reports which could enhance current technology are urgently needed. especially, membrane materials that are less expensive, comfortable to be held, disposable, and effective at pathogen elimination. These may want to greatly impact our capability to offer secure ingestion water to the worldwide populace and Uganda mainly. 

Looking at nature for the suggestion, we found that a potential solution exists in the form of plant xylem. “A porous material that conducts fluid in plants. Plants have evolved specialized xylem tissues to conduct sap from their roots to their shoots. Xylem has evolved under the competing pressures of offering minimal resistance to the ascent of sap while maintaining small Nanoscale pores to prevent cavitation.” Whereas statistics showed a fair coverage of safe water in the sub-county, the reality on the ground is alarming. The sector is faced with several challenges including inadequate water sources amidst the high population (2000 people) non-functional of only 32 boreholes working out of the 46, unsafe water sources, and irresponsible communities.

1.1 Problem Statement 

 The Uganda Demographical and health survey in 2008 reported that the prevalence of diarrhea amongst children in Uganda is 20% caused by some bacteria: campylobacter, salmonella, and vibrio cholera in the domestic consumed contaminated water which has caused 6.41% of the total death making country to be the seventh worldwide (Pande, Kwesiga, Bwire and Ario, 2018). The deadliest elements inside the contaminated water are the bacterial beginning: Infections and diseases such as dysentery, typhoid, and cholera. Pathogens viruses, protozoa, or parasites are the most common and extensively spread fitness risks related to drinking water. This creates a vacuum for research on all possible filtration technologies by researchers to curb the growing challenges of drinking contaminated water. The conventional methods of treatment like the use of rapid sand filters and slow sand filters disinfect water from pathogenic bacteria to relatively low efficiency and are expensive for low-income earners and so the challenge should be addressed. In Ndejje village Luweero district, a similar gap relating to poor quality of drinking water is a growing challenge due to contamination of the water sources i.e. Nabanga water stream, and this comes with its adverse effects as mentioned. Effective methods to curb these challenges should be accessed to provide an alternative pathogenic filtration technology-xylem filtration.

1.2 Justification

This research was intended to analyze the effectiveness of the xylem filters in removing biological pathogens from water in that the filtered water can be used for drinking. Research also aimed at determining the efficiency, and rate of filtration of xylem filters at removing pathogens at the lowest cost. Using relative approaches, we analyzed the well water for quality. The quality parameters were then compared with the standard maximum allowable for drinking water and water for domestic use.


This paper’s methodology section presents the research assumptions, study design, experiment setup, sampling procedures, and laboratory tests carried out to determine the efficiency and effectiveness of sand filters. The study involved collecting raw water samples from an underground stream in Nabanga village, filtering them using a prototype made of a tree branch and xylem filter, and testing for parameters like pH, DO, faecal coliform bacteria count, T.D.S, E-Coli, and iron. The laboratory tests included testing for total coliform and E-coli levels using specific methods and reagents. Safety gadgets were used during sampling to prevent contamination of samples.

2.1 Research assumptions 

 The research was done based on two credible assumptions which were that the xylem used was got from tree branches during the pruning process and that the raw water samples contain a higher percentage of pathogens and bacteria.

2.2 Study design

The study involved sampling of underground water effluents from Nabanga village 1 kilometer away from the Lady Irene campus 100 meters away from Iganga Nursing School.

2.3 Experiment setup

The setup for the experiment used items like the xylem, two 20-liter containers, 1-meter horse pipe, 500 millimeters PPR, a stop valve, a 1.5l filter chamber, and a 20 bar Pressure chamber as shown in Image 1

Image 1: Showing the experiment setup

2.4 Preparation and set up of the experimental prototype

A branch was cut from one of the coniferous trees from the lady Irene campus and shaped to a dimension of 75mm using a shaping machine. Lake sand and charcoal were washed until it was clean to remove silt and charcoal dust. It was then air-dried and sieved using the U.S standard sieves. PPR is connected to the stop valve on either end and sealed with a thread seal to ensure minimum leakage during operation. The xylem filter chamber in conjunction with the pressure chamber is connected at the lower end of the PPR. The cut tree branch should be placed in water to prevent the xylem from ‘dying’ as shown in Image 2.

Image 2:Tree branch in water to prevent xylem from dying

2.5 Sampling

A 5-liter jerrican was used to collect raw water from underground stream water during morning hours. This helped us to determine the quantity of pathogenic content in underground water. 

A 20 liters container was used to carry raw water to where the experiment was set up. Another 20 liters container was used to collect filtered water.

A 20-bar pump was used to increase the efficiencies of filtration through the xylem filter. It would take 15 hours to filter 5 liters of jerrycan. 

While sampling, safety gadgets like overalls, and gloves were used to avoid contamination of the sample and protection. The filter chambers were fed in intervals of 1 liter and samples of raw water and filtrate were taken for testing the available parameters in the  Ndejje University water laboratory. This helped us to know the efficiency and effectiveness of sand filters. These parameters included, pH, DO, Fecal coliforms bacteria count, T.D.S, E-Coli and Iron for both the raw water and filtrate.

2.6 Laboratory Tests for the Status of the Sample 

In the laboratory, several tests were carried and these included testing for the following;

  • Total coliform and E. coli
  • Dissolved oxygen 
  • PH
  • Irons test 
  • Total suspended solids

These parameters were tested using their specified methods, which included;

2.6.1 Testing for the Total coliform and E-coli levels in the sample

Method used: 

A measured sample of 100ml or its equivalent is filtered through a membrane filter composed of cellulose esters which retain all the bacteria on the surface of the membrane, which is then incubated with the girded side upon a selective medium.

Reagents and nutrients

Laurel sulphate both Weigh 38.1g of anhydrous broth powder and dissolve in 500ml of water Dispense in 100ml volumes or smaller volumes in screw-capped bottles. Sterilizes in an autoclave for 15min at 121oC 15 bars. Remove media and store in a dry pace.

Equipment and apparatus

Filtering unit, Membrane filter pads, autoclave, Incubator, Petri dishes, forceps, pipettes (graduated), transfer pipette, digital counter, water still, measuring cylinders, sterilizing burner, hot plate, disinfectant (ethanol 70%), weighing balance, and a thermometer.


The membrane filter was picked and placed using sterile forceps ascetically.

A 2.0-2.5 ml of Laurel Sulphate broth was transferred onto the absorbent pad in the Petri dish so that it is socked just to leave a film of broth around the absorbent pad. Avoid over-flooding the Petri dish with both.

With the gridded face up and the filter, the jar was replaced.

100ml or an equivalent of the sample was poured and filtered into the filtration jar and all of it was filtered through the filter paper.

Then the filtering membrane was removed and placed on to the absorbent pad that was earlier socked with the broth (The gridded side of the filter membrane should face up)

The Petri dish as shown in Figure 3 was covered with the lid uppermost and placed onto the Petri dish carrier then placed in the incubator. The incubator should be set at 44°C ± 0.5°C for the total coliform test (while for total coliform it should be set at 35°C ± 0.5°C for 30min before the sample is an incubator. Ensure the thermometer is placed in the incubator to cross-check the temperature then incubate for 12-16 hours.

After incubation the carrier plus the petri dish were removed and allowed to cool for 10min, to allow the false yellow color to lose color and ensure that the yellow is only for the typical colonies.

A magnifying glass and a counting pen were used to count the colonies as shown in Figure 4.

Count all the yellow, and pale yellow colonies which are convex, dome shape colonies with a reflecting surface as true colonies if incubated at 44oC it may be total coliform or suspect E.coli form but if incubated at 35oC then it may be considered a total coliform.

However, the suspected E. coli form should be confirmed using both brilliant green broth and Tryptone water. Coliform colonies/100ml= coliform colonies counted / ml sample * 100

Image 3: Petri dish indicating E-coli bluish and total coliforms

Image 4: Counting bluish E-coli on a petri dish

2.6.2 Testing for the levels of dissolved oxygen (DO) in the sample

The method used to determine the amount of dissolved oxygen in the sample was the Iodometric method – (TCVN7324:2004 (ISO5813:1983) Water quality

2.6.3 Testing for the levels of Iron in the sample

The iron in the sample was tested using the procedure detailed below;

Pre-treatment of the sample. 

The following types of pre-treatments were to be applied for the various forms of iron to be determined as shown in Table 1. The determinations had to be made as soon as possible after the sample was collected especially for soluble iron. When the sample to be analyzed for total iron was measured and acidified, it was safely stored.

Table 1: Pre-treatment mechanisms for the different iron forms

Iron FormPre-treatment mechanism
Total IronThe sample was mixed thoroughly, measured, and treated.
Dissolved IronThe sample was allowed to settle, then decanted and the supernatant was filtered through fine filter paper, and the first portion was discarded. A measured volume of the filtrate was then measured.
Suspended IronDetermine total and dissolved iron and calculate the suspended iron by subtracting the dissolved from the total iron.

Color development

If the sample is expected to contain less than 2.4 mg of Fe per liter, pipette a 50.0-ml aliquot into a 125-ml Erlenmeyer flask. If the sample is expected to contain a higher concentration of iron, accurately measure a smaller aliquot that will contain less than 0.12 mg of Fe, and add distilled water to make the volume about 5O ml. Add 2.0 ml of concentrated hydrochloric acid and a few glass beads. Heat to boiling and boil gently for S minutes to bring all the iron into the solution. Cool to room temperature, transfer to a 100-ml volumetric flask, and add 1 ml of hydroxylamine hydrochloride solution, 10.0 ml of sodium acetate solution, and 10 ml of phenanthroline solution. Dilute to the mark with distilled water, mix thoroughly, and allow to stand for 15 minutes to permit full-color development. Compare visually with the standards in Nessler tubes.

Calculation: Fe (mg/1) = mg of Fe/ ml of sample*100

2.6.4 Testing for the levels of Total Dissolved Solids (TDS) in the sample

The total dissolved solids were tested using the American Public Health Association, Standard Methods for the Examination of Water and Wastewater 20th Edition (SMEWW) 2540-Solid-C Total Dissolved Solids Dried at 180°C

2.6.5 Testing for the pH levels of the sample.

Applied Method: TCVN6492:1999 (ISO10523:1994) Water quality – Determination of pH

Apparatus: The apparatus used was the multi-meter for pH measurement as shown in Image 5.

Image 5: Multimeter used in pH level tests


The sand used in the filter media and in the preliminary treatment chamber was graded using the sieve analysis method and the results were tabulated in Table 3, these same results were also graphed as shown in Figure 1.

Table 2: Results from the sieve analysis of the sand used in the filter media and the preliminary treatment chamber

Figure 1: A graph showing the percentage passing against the sieve size from the sieve analysis results

From the Figure 6;

d10 = 0.20 mm   

d60 =1.90 mm                                

From allowable parameters for effective sand size (d10 = 0.1-0.35mm)

Thus, our sand used in the proto-type filter qualifies

The coefficient of uniformity d60/d10=1.90/0.20=9.5 though the allowable coefficient of uniformity is 2-3.

The filtered water was also tested for TDS, DO, pH, E-coli, Total Coliforms, and iron levels using the methods stated earlier. The results obtained were then tabulated for easy comparison in Table 3.

Table 3: Parameter Levels for the filtered water

The results for the influent and the filtrate parameter levels were then compared to check the effectiveness and percentage removals of the filter for the different parameters. This was tabulated as shown in Table 4.

Table 4: Percentage removal from the comparison between influent and filtrate parameter levels

The parameter levels of the filtrate were also compared against the national standards and tabulated in Table 5. From the analysis, the parameters of E-Coli were removed to acceptable values for drinking water, iron was reduced, while Total coliforms were uncountable, T.D.S increased but in the acceptable parameters of drinking water and pH remains constant before and after filtration. 

Table 5: Table 5:Comparison of filtrate parameters with national standards


Overall, this research has shown that xylem filter can to a greater percentage treat underground water. The xylem filter increased D.O, T.D.S, reduced iron, and completely removed E-coil. Total coliform remained unfiltered and uncountable. As the pH was as per the standards of international water quality for drinking. The removal of total coliform can fur be removed by a control process of boiling the filtrate which would remove or reduce Total coliform from the filtrate making it suitable for drinking. In relation to the maximum allowable standards for drinking water, the xylem filter is not sufficient to treat underground water to a suitable state thou it can treat to a greater percentage despite the filtrate being microbiologically contaminated. The system was able to qualify in the parameters of T.D.S, D.O, pH, E-coil, and iron but total coliform needs to be removed using further treatment and disinfection.


For the xylem filters to suit the design purpose of treating groundwater from bacterial pathogens 100% control measures such as boiling the filtrates are recommended. Based on the above results we recommend that the technology is sufficient to filter underground water from the most dangerous microbiological (E-Coli), there is a need to incorporate the technology in different homes as extra technologies are developed to manage Total coliform, as per the standards of international water quality for drinking.


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