Tuesday July 05, 2022

Treating water

October 31, 2018

Waterborne diseases have been troubling Pakistan for the past many years. National drinking water statistics estimate that only 36 percent of the water is safely managed and the management of drinking water sources and supply systems in the country has been declining in the recent years.

This situation is alarming because of how it impacts human health. The whole country is being affected by marginal water availability and poor water quality. These threats lead to acute outbursts of waterborne diseases. The most vulnerable include children under the age of five and underwater life. Multiple factors have led to these issues, including the direct discharge of domestic and industrial wastewater to surface water sources and the poor state of water and wastewater infrastructure. Leakage from sewers and seepage from open wastewater drains contaminate surface water, groundwater, and soil.

Clean water is a basic human need and governments have largely failed in fulfilling this need. We have seen hundreds of research studies being conducted annually on water quality issues in Pakistan. The majority of these studies identify poor infrastructure as one of the major causes behind the lack of clean drinking water, along with direct discharge of domestic wastewater and industrial effluent into fresh water bodies.

In recent years, there has been a drought situation in the Thar region — resulting in lack of access to safe drinking water, and malnutrition among the region’s population. Back in 2015, former president Asif Ali Zardari inaugurated a reverse osmosis filter plant (described as Asia’s biggest) in an effort to improve the drinking water supply for the people of Thar. The plant was functional for not more than six months. It would have been much better if the investment had been done in managing water to ensure water availability in the region. At present, the federal government is already facing challenges due to severe financial mismanagement and debt crisis. Developing new infrastructure and improving the current one seems too distant in the future.

One of the possible ways to alleviate this situation is to rely on effective Point-of-Use (POU) treatment devices that are efficient enough to remove contaminants and provide clean drinking water to the households. There is a long list of such devices available in the market with some of these devices claiming perfect results, like 100 percent removal of microorganisms and heavy metals. It is crucial to make evidence-based choices between products since human health is at stake. It is time to educate people about the different contaminants they have been consuming along with drinking water, and the technologies that can get rid of these contaminants, and to ensure the provision of safe drinking water.

The most common of all techniques is simply boiling the water. There is a misconception among the people that boiling water will kill all of the foreign species in the water including microorganisms (viruses, bacteria, protozoa etc). This assumption, however, is far from reality. It was considered a good approach to rid water of impurities and microorganisms in the past when chemical contamination was much lower. Boiling water may result in inactivation of microbes but it may exaggerate contamination levels by acting as an energy source (catalyst) for some chemical reactions to occur. Boiling water, therefore, is not a good approach to getting safe drinking water when there is chemical contamination in the water.

The second most common approach is the use of chlorine-based products in powder, capsule, or liquid form. Using these products further increases contamination in water bodies by releasing by-products. They are effective in disinfection but need large concentrations and sufficient time to give favourable results. Using chlorination results in the discharge of by-products (that are chemical contaminants by themselves) into water bodies.

POU treatment devices are seen as an emergency approach and mostly used in the worst conditions. However, in the case of Pakistan, this is the most feasible approach to be adopted. This approach has been widely accepted with cartridge-based devices (either two-stage or three-stage) being the most commonly used POU systems throughout Pakistan. The three-stage devices are better because each stage removes a unique type of contaminant. Stage 1 is for removing dust, rust and suspended particles. Stage 2 removes turbidity, odour, and some of the organic and inorganic chemical species. Stage 3 is a disinfection unit that uses a UV lamp.

The three-stage treatment system is energy-intensive but effective. There is a need to develop energy-efficient and cost-effective three-stage POU treatment device which must be pursued by the water research community in the country. The government too must invest in such endeavours to encourage researchers to come up with innovative and cost-effective water treatment approaches.

The writers are PhD researchers at the University of Utah.;