A Review of Wastewater Pollution, Its Impacts, and Treatment Challenges in Pakistan

Abstract

Global freshwater resources are under unprecedented strain, with water demands already surpassing supplies in regions inhabited by over 40% of the world's population. This scarcity is exacerbated by the widespread deterioration of water quality due to pollution from industrial discharge, municipal sewage, and agricultural runoff. Wastewater is a significant source of this pollution, containing harmful pathogens, organic matter, and toxic heavy metals that pose severe risks to human health and ecosystem integrity. In Pakistan, the situation is critical; the country faces severe physical water scarcity and rampant water pollution, with less than 10% of its municipal wastewater receiving any treatment. This review synthesizes the current state of knowledge regarding the composition and sources of wastewater in Pakistan, its detrimental impacts on human health—particularly through the contamination of the food chain—and the associated challenges in wastewater treatment. The analysis highlights the extensive use of untreated wastewater in agriculture due to its perennial availability and nutrient content, a practice that offers short-term economic benefits but leads to long-term consequences, including the accumulation of heavy metals in soils and crops. Finally, the review discusses the potential of constructed wetlands as a sustainable, low-cost treatment technology suited to the economic and technical constraints of Pakistan, offering a viable alternative to energy-intensive conventional treatment methods.