Water is perhaps the most abundant yet inaccessible resource available on Earth. The amount of water that is currently available for use is infinitesimal compared to the quantity of unusable water in oceans and ice caps. Water scarcity has become a dire problem. An obvious solution is reusing water that is available. Unfortunately, the potential for reuse has not been fully realized in the European Union (EU). The current challenges include:
- Water reuse expenses are high (developing wastewater treatment plants (WTPs), potable and non-potable water segregation)
- Lack of unanimous legislation across EU members
- Scope for public distrust (capitalism-based paranoia, health risks)
The European Commission (EC) has initiated a discussion aimed at overcoming these problems and promote safe water reuse protocols. Based on a legislative proposal of minimum quality requirements (MQR) by the EC, their Joint Research Centre (JRC) was commissioned to prepare a scientific report (now published) which proposed MQR for reusing water on two primary fronts - aquifer recharge & agricultural irrigation.
The EC asked the Scientific Committee on Health, Environment and Emerging Risks (SCHEER) and the European Food Safety Authority (EFSA) for their scientific advice and commentary (Rizzo et al., 2018). SCHEER believes the MQR proposal does not provide sufficient shielding against 3 primary environmental risks.
● Effluent contamination risk: There would be an unwanted occurrence of Water Framework Directive (WFD) priority chemicals and the contaminants of emerging concern (CECs) such as personal hygiene and beauty products, pharmaceuticals, microplastics, etc. in WTP effluents (Pal et al., 2014).
● Antibiotic resistance risk: A pressing issue is a possibility of WTP effluents creating antibiotic resistance in irrigated crops. These effluents have a high proportion of mobile genetic elements like bacteria that carry antibiotic resistant genes which could assist antibiotic resistance in plants and soil (Rizzo et al., 2013; Becerra-Castro et al., 2015). The report failed to account for this known risk to water resources as well as humans and animals.
● Microbiological risk: The report does not account for the microbiological risk involving bacterial regrowth in treated wastewater storages which supply to irrigation. Extra care is needed as bacterial regrowth cannot be completely stopped under regular operating conditions found in WTPs (Li et al., 2013; Fiorentino et al., 2015).
These risks can be minimized and water reuse can be made safer with a minimum required tertiary treatment that includes conventional filtration and then disinfection. However other processes such as adsorption and advanced oxidation should be implemented when economically sustainable.
An appropriate program for monitoring should be implemented that checks CECs, indicators of antibiotic resistance, and disinfection byproducts along with the conventional parameters (TSS, COD, etc.). The precise nature of monitoring should be based on the current advancements at the EU level.
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