Harare, the capital of Zimbabwe, is facing serious water quantity and quality problems, with severe pollution downstream in Lake Chivero. These issues are often attributed to rapid population growth, inadequate maintenance of wastewater treatment plants, expensive technologies, and a poor institutional framework.
The worst-affected areas are high-density suburbs that accommodate low-income earners—Glenview, Budiriro, and Glen Norah—where raw sewage flows through the streets.
If left untreated, this poses dangerous health risks to the community and will be costly to manage in the event of disease outbreaks such as cholera, dysentery, and typhoid.
Glenview and Glen Norah are particularly vulnerable due to underground water contamination from uncontrolled sewage flow.
Harare’s tap water has been alleged to be unsafe for human consumption.
The mere sight of water flowing from a tap can deter even the thirsty.
If stored for a few days in a container, the water turns greenish, and algae begin to develop.
The consistent outbreaks of cholera in the capital city are deeply worrying, and out-of-the-box thinking is urgently needed to address this seasonal catastrophe.
According to UNICEF, Zimbabwe recorded 26,708 cholera cases in 2024, with 569 deaths across 62 districts.
Harare alone accounted for about 60% of the cases.
Untreated sewage is contaminating drinking water sources, with gut bacteria like Escherichia coli, Klebsiella, and Enterococcus—clear indicators of fecal contamination being detected during water analysis.
This write-up will explore cost-effective and reliable methods for wastewater treatment, promoting a safe environment for biodiversity and safe water.
The treatment method discussed here could become a best practice for poor and developing countries.
As such, it urges relevant departments to explore alternative solutions for ensuring safe water for human consumption.
Among various cost-effective wastewater treatment approaches, this article focuses on bioremediation, a biotechnology-based method.
Wastewater treatment is a pressing global concern, as the discharge of untreated effluent poses severe environmental and public health risks.
Chemicals and excess nutrients disrupt aquatic ecosystems, leading to algal blooms and depleted oxygen levels.
These problems often violate the World Health Organization’s water quality standards for both surface and groundwater.
Globally, approximately 300 billion m³ of municipal wastewater is generated each year, with projections estimating a 24% increase by 2030 and 51% by 2050.
On average, most cities in developing countries discharge 30–70 mm³ of wastewater per capita per day. Meanwhile, the availability of freshwater continues to decline.
Although conventional wastewater treatment methods were previously used to address this issue, innovative and sustainable alternatives like bioremediation are gaining prominence.
A case in point is the Hudson River in the United States, which was cleaned using bioremediation after being contaminated with polychlorinated biphenyls (PCBs)—toxic chemicals that threatened aquatic life and human health.
Conventional methods like dredging were costly and environmentally harmful. In contrast, bioremediation using Dehalococcoides bacteria broke down PCBs into harmless by-products under anaerobic conditions.
Biotechnology offers various solutions to effectively remove contaminants and provide safe environments.
Advanced filtration techniques using biodegradable membranes can remove harmful microbes and pollutants, ensuring water meets safety standards for human consumption.
Bioremediation enhances traditional biological wastewater treatment methods by introducing microbes, enzymes, or plants to degrade pollutants.
These techniques include both aerobic processes—using Pseudomonas and algae in systems like activated sludge and biofilters and anaerobic processes.
Bioremediation thus serves as a crucial tool in the quest for clean water.
A study conducted at the Karoi water station in Zimbabwe demonstrated the effectiveness of phytoremediation, a type of bioremediation.
The study used Azolla filiculoides, a small free-floating freshwater fern.
Water quality parameters such as pH, nitrates, and phosphorus were measured before and after treatment, showing a significant improvement in water quality.
Bioremediation offers several advantages as it improves hazardous waste cleanup efficiency, reduces energy consumption and emissions, and lowers the risk of contamination.
However, it is limited to biodegradable compounds.
Despite this limitation, it remains a promising technology for addressing environmental pollution.
Lake Chivero, heavily affected by sewage effluent, could benefit from water hyacinth (Eichhornia crassipes)—a fast-growing aquatic plant originally from Brazil.
This plant can absorb and digest contaminants when used in floating wetlands, effectively filtering wastewater.
Though water hyacinth is considered a weed due to its aggressive spread, its regenerative properties make it a powerful natural water purification system—at a fraction of the cost of a standard sewage treatment facility.
In light of Harare’s growing water crisis and recurring disease outbreaks, adopting sustainable and affordable wastewater treatment methods is essential.
Bioremediation, supported by biotechnology, presents a practical and eco-friendly solution for improving water quality.
With political will, public awareness, and investment in scientific innovation, bioremediation can transform waste into a resource and secure clean water for communities struggling with inadequate sanitation infrastructure.