Scope of this Project
This project is focused on assessing the performance of various water filters with regard to removing bacteria, turbidity, and chemicals from drinking water in order to make it safe for human consumption.
As such, we will compare water quality from four different locations of Karachi, and then use three different commercially available water filters to assess their performance. The water collection process is shown in the videos and figures below.
Equipment Used
The three types of filters used are shown below. All three filters were purchased from Trading Corporations Water Filters located at 10, Japan Mansion, Preedy Street, Saddar, Karachi. Ph 021 327 20461.
China Aqua Gold
China Aqua Gold with Three Stage UV. The price for this system is Rs 4000. This filter system uses electricity for ultraviolet steriliza on and has three stages. The first stage uses a cotton roll called PPF and removes dust and large particles. The second stage carries out fine filtration using a mesh type filter, and the third stage is for UV sterilization using electricity. A picture of this filter is shown below:
Aqua Safe Filter
Aqua Safe Three Stage Filter without UV . The price of this filter was Rs 6000 and has the same first and second stage as the China Aqua Gold Filter, and for the third stage employs a reusable Musaffa bag approved by PCSIR. The Musaffa bag needs to be replaced every two to three months, or when the color of the bag changes from white to green color. Picture of this filter and replaceable bag is shown below:
Nova Purifier Filter from China
Nova Purifier Filter from China with a ceramic filter element. The price of this filter is Rs 2500.
This unit consists of two chambers . Water is poured into the upper chamber, which has a capacity of 1 gallon, and passed through the filter element overnight. As such, this filter requires 10 hours to filter all the water in the upper reservoir as shown in the figure below
Three types of water bottles were for collection samples. Large glass or plastic bottles for collecting samples used for chemical analysis and small sealed and sterilized plastic bottles for samples tested for bacterial analysis. The sterilized bottles were obtained from PCRWR located at Regional Centre, University Rd, Block 1 Gulistan-e-Johar, Karachi. The sterilized bottles cost Rs 15 each. See images below.
One 19 liter plastic bottle for water collection. This general purpose bottle was washed and dried prior to each use.
Insulated Ice Box of capacity 20 gallons t ransporting water samples at cold temperature from NED lab to PCRWR for water quality testing. See image below:
Locations for Water Collection
Manzoor Colony Water Collection was done from
https://goo.gl/maps/KcwwrZthBX1zGej67
NIPA Water Collection was done from
https://goo.gl/maps/UiGEp5872gQLP4898
Jinnah Hospital Water Collection was done from https://goo.gl/maps/KcwwrZthBX1zGej67
KDA Chowrangi in North Karachi was done from
https://goo.gl/maps/i9bzvsbGyeFhZDEm6
Test Method
In order to minimize test errors, sterilized bottles purchased from PCRWR were used. Specifically, two sizes of bottles were used – 19 liter and 1 liter. The large bottle was used to collect water from the locations under study.
For example, we got 19 liters of water from Manzoor Colony and brought it to the lab. This sample was then divided into four parts. One part was used to establish the baseline quality of the water. The other three samples were passed through each of the three water filters shown above.
The post-filtered water was then taken to PCRWR for water testing. In this way, we had four water samples for each of the locations listed above: a) Pre-filtered water (as-is from location water was collected from), b) Water that was filtered using the China Aqua Gold Filter, c) Water that was filtered using AquaSafe Three Stage Filter without UV, d) Water that was filtered using Nova Purifier Filter from China.
The setup for filtering the water collected from each location using the three different types of systems. Water brought from the test location was put in the large blue reservoir and transferred via plastic pipes to the inlet of each filter. After filtration, the water was collected in the smaller bottles for chemical and bacterial analysis.
The above figure shows the bench setup for collecting filtered water from the Nova Purifier filter.
Lab Testing of Water Samples
All water samples were tested at Pakistan Council of Research in Water Resources (PCRWR). Each test cost Rs. 3,000 for chemical and bacterial analysis. We performed a total of 16 tests across 4 locations of water collection. For each location, one sample of unfiltered water was tested and three samples of post filtered water were tested (one each for China Aqua, Aqua Safe and NOVA Purifier filters). The receipt for the testing is shown below.
Example of Chemical and Bacterial analysis results from the lab are shown below.
Test Results
The water quality for the raw sample as well as the post filtered samples using China Aqua Gold, Aqua Safe and Nova Purifier filter can be found in the tables below. Note that only one type of filter was used for any sample being filtered (rather than filtering a water sample through multiple filters in succession). This allowed side-by-side comparison.
- Manzoor Colony. The results shown in Table 1 below:
The data shows that the unfiltered water is not suitable for human consumption. After filtra on, both the China Aqua Gold and Aqua Safe remove the Fecal Coliform and E Coli bacteria, but there is a small trace of Total Coliform. Meanwhile, the Nova Purifier filter is ineffective and in fact has a higher level of bacteria than the raw data, suggesting high sample to sample variability in bacterial content for water collected from the site. As far as the other indicators are concerned, the turbidity performance of Aqua Safe and Nova Filter is better than the China Aqua Gold.
- NIPA Water: The results shown in Table 2 below:
The data shows that the unfiltered water is not suitable for human consumption. After filtra on, both the China Aqua Gold and Aqua Safe remove the Fecal Coliform and E Coli bacteria, but there is a small trace of Total Coliform in the water filtered using China Aqua Gold filter. However, like the data for Manzoor Colony, post filtered total Coliform is quite low and in the noise level.
Finally the Nova Purifier filter is ineffective in removing all types of bacteria which are found post fi ltration as well. Moveover, bacteria count is higher for Fecal Coliform and E Coli after filtration using the Nova Purifier Filter. This may suggest that any traces of bacteria in Nova Verifier Filter may multiply overtime. As far as the other indicators are concerned, the turbidity performance of Aqua Safe and Nova Filter is better than the China Aqua Gold filter.
- KDA North: The results shown in Table 3 below
The data shows that the unfiltered water is not suitable for human consumption. After filtration, China Aqua Gold was the only filter that removed all types of bacterias. Whereas the Aqua Safe and NOVA Purifier filters were ineffective in removing bacteria although Aqua Safe was slightly better. As far as the other indicators and turbidity are concerned, all 3 filters performed sa sfactory.
- Jinnah Hospital: The results shown in Table 4 below
Table 4. Jinnah Hospital Lab Analysis Results – unfiltered water, and post filtration
The data shows that the unfiltered water is not suitable for human consumption. After filtration, China Aqua Gold filter removed Fecal Coliform and E Coli bacterias. Whereas the Aqua Safe and NOVA Purifier filters were ineffective in removing all bacteria although Aqua Safe is clearly better. As far as the other indicators and turbidity are concerned, all chemical indicators are satisfactory however the China Aqua Gold and NOVA Purifier filters did not perform as per expectations.
Key Conclusions
- NOVA Purifier filter was not able to remove bacteria in all four samples we tested. As such, we will not use it in our future work and field deployment.
- China Aqua Gold was the best performing filter in terms of removing bacteria for 3 out of 4 locations that we studied. Moveover, based on the complete data set, we estimate that this filter is able to remove more than 90% of Coliform bacteria in a sample.
- Aqua Safe filter performed best in NIPA Chowrangi sample but the results were close to China Aqua Gold filter.
- As far as the turbidity results are concerned, Aqua Safe and NOVA Purifier filters were successful in all of 4 cases whereas China Aqua Gold showed high turbidity in 3 out of 4 sample locations.
Next Steps
- We will repeat the water testing for the 4 locations using China Aqua Gold and Aqua Safe Filters to determine which filter should be used in the field testing.
- Engage NED faculty to identify interns for the next phase of this project.
