According to the 2017 United Nations World Water Report, globally, 16% of industrial, 8% of municipal, and 3% of agricultural wastewater is being released into the environment.
Wastewater is a simple term that can be described as “used water” or water that contains waste from different industries like textile, agriculture, dying, paint, chemical, etc. The sources of wastewater can be divided into three types: domestic, sewage, and industrial wastewater. Globally, it is most likely that about 80% of wastewater is released into the environment without proper treatment (UN Water, n.d.).
According to the 2017 United Nations World Water Report, globally, 16% of industrial, 8% of municipal, and 3% of agricultural wastewater is being released into the environment (UNESCO World Water Assessment Programme, 2017).
Water demands have increased significantly over the past few years, and since the population is increasing at an exponential rate, the percentage of wastewater will also increase.
The release of untreated wastewater into oceans and seas will ultimately lead to an increase in hypoxia, which is a common term used for dead zones, i.e., low levels of oxygen in water, that will ultimately affect aquatic life and so on.
There is growing concern about treating the wastewater; however, it is estimated in Asia and Pacific regions that about 80% to 90% of wastewater is being produced, which is released into the environment untreated, ultimately polluting groundwater, surface water, and other water resources as well (UNESCAP, 2013).
Pakistan, once a water surplus country, is now a water-deficient country. The water quantity has decreased to 1100 m3 per capita in 2006 and is projected to decrease to 700 m3 per capita by 2025. In Pakistan, wastewater released from different sources is directly discharged into natural drains, septic tanks, or other water bodies nearby.
Cities that have proper wastewater treatment have a low proportion of wastewater before disposal. In Lahore, about 12.5% of total wastewater is produced annually, out of which only 0.01% undergoes the treatment process; the rest of the water is discharged directly into other water bodies: Karachi (26.3%), Faisalabad (5.6%), Hyderabad (2.2%), and Peshawar (2.3%).
Produce wastewater annually, yet only 15.9%, 25.6%, 34%, and 36% of water are being treated before discharge, respectively.
However, other cities like Gujranwala, Sialkot, Multan, and Rawalpindi don’t follow any specific wastewater treatment procedures and dispose of their water directly into lakes, streams, and rivers, which leads to the deterioration of the quality of the aquatic environment.
Total wastewater discharge into major rivers is 392,511 million gallons, which includes 316,740 million gallons of municipal and 75,771 million gallons of industrial effluents.
Dairy Industry
Pakistan’s population in 2020 will be about 222,540,111, making it the 5th most populous country in the world, which is equivalent to 2.83% of the total world population. Despite decreasing gross domestic product (GDP), the milk sector and other major dairy production systems are still playing a major role in the national economy.
Pakistan is the 4th largest milk or dairy product in the world. In 2019, its production is estimated to have increased by up to 3% and produced about 47297 thousand tonnes of milk. Water is used in different stages of making milk or dairy products.
Estimated wastewater discharged from the dairy industry is about 1452.95 gallons to 7925.16 gallons per day during vehicle or tanker cleaning, floor cleaning, equipment cleaning, or condensed water during the milk evaporation procedure.
Textile Industry
The textile industry, which is the major industry in the industrial sector of Pakistan, plays a great role in the economy and shares 7.4% of the GDP of Pakistan. In Asia, Pakistan is the 8th largest textile exporting country.
Textile wastewater contains many hazardous chemicals and heavy loads of metals. However, some vital nutrients like copper, zinc, and manganese can also be found in textile wastewater. It is estimated that about 1,441,167 m3 of wastewater is being released per day during different processes that are being carried out by the textile industry.
Paper and pulp industry
At present, there are about 100 units in the paper and pulp industry that use wheat straw and bagasse as raw materials for the production of paper. It is estimated that the amount of wastewater that is produced in the paper and pulp industries is 205.6 m3/tonne of product that is being produced (S. Akhtar, 2013).
Agricultural Industry
The agricultural sector is considered to be the “backbone” of Pakistan’s economy. It contributes about 18.9% to the GDP of Pakistan (tribune.pk, 2020). The main agricultural products that are produced in Pakistan are wheat, cotton, sugar cane, rice, fruits, and vegetables.
Globally, Pakistan is ranked seventh, fourth, and sixth largest producers of wheat, cotton, and sugar, respectively. In a report, it is estimated that about 16% of wastewater is being discharged by the agricultural sector in Pakistan per year (G. Murtaza, 2013). And much of the wastewater is used for the irrigation of crops without proper treatment.
Automobile Industry
The automobile industry is another sector that is playing a huge role in the national economy of Pakistan, contributing 2.8% to its GDP. Almost 3200 automobile manufacturing plants are running in a country that is producing almost 200,000 vehicles and 1.8 million motorcycles. The wastewater that is produced by a single plant is almost 2.1 m3/hour however, this wastewater will be circulated for other purposes later on.
Recommended solutions:
Physical treatment
Physical procedures are utilised to purify the effluent at this stage. To remove the solids, processes such as screening, sedimentation, and skimming are used. There are no chemicals used in this technique.
- Aeration is another excellent physical water treatment technology. This method involves moving air through the water to offer oxygen to it.
- Filtration is utilised to remove all pollutants. To pass the effluent and separate the pollutants and insoluble particles present, specific filters can be used.
Biological Treatment
This employs a variety of biological processes to degrade organic substances found in wastewater, such as soap, human waste, oils, and food. In biological treatment, microorganisms decompose organic materials in wastewater.
Chemical Treatment
This treatment involves the use of chemicals in water. Chlorine, an oxidizing chemical, is frequently used to destroy microorganisms that degrade water by introducing toxins into it. Ozone is another oxidizing agent used in wastewater treatment. Neutralization is the process of adding an acid or base to water to bring it back to its natural pH of 7. Chemicals prevent germs from growing in water, resulting in pure water.
This article is jointly authored by Kaynaat Akbar, Rao Muhammad Sajjad Sharif, Shahid Majeed.