Unlocking the role of water reuse

The 13th IWA International Conference on Water Reclamation and Reuse, held in Chennai, India, in January, saw leading experts in water reclamation and reuse come together to present on and discuss the role of water reuse in overcoming the challenges of growth and climate change. Here, some of the leading speakers share their views. 

Melissa L Meeker, Chief Executive Officer, The Water Tower, USA  

We have seen potable reuse projects around the world that have failed to get off the ground, and those that have been a great success. Many times, the outcomes can be linked to public engagement, through either the failure to proactively address stakeholder concerns, or because of the conscious, consistent, and comprehensive inclusion of stakeholders. 

The role of public engagement is well documented in potable reuse social science. Although, in many instances, it is an afterthought, public engagement and community acceptance are critical to the success of a project’s implementation. By reviewing past research, collating successful case studies, and analysing failed projects, we are able to identify best practices that can be used to guide leaders charged with managing a community’s water management system.  

In 2023, the IWA Water Reuse Specialty Group’s Social and Economic Dimensions of Water Reuse Working Group will have a series of collaborative meetings to develop additional best practices and collate engagement materials that can be adapted for use in new programmes across the globe. As many utilities do not have the resources for in-depth engagement programmes, tools that can be easily adapted could provide the necessary support for reuse project implementation in areas that face water scarcity.

Professor Ligy Philip, Institute Chair Professor at the Department of Civil Engineering, Indian Institute of Technology Madras 

Water scarcity is a major problem faced by most developing countries. The indiscriminate discharge of untreated and partially treated wastewater is deteriorating the quality of already dwindling water resources. Wastewater treatment and reuse is the most sustainable solution to tackle these problems and provide a reliable source of water throughout the year.  

Chennai has faced severe water shortages for many years. In 2019, water was brought to the city by train, as there was none available in the city for drinking and other domestic purposes.  

Known as the city of lakes, Chennai is blessed with many large and small water bodies. Unfortunately, all of these water bodies are rainfed systems. When the monsoons fail, these lakes are dry. Often, these water bodies are filled with solid and liquid waste, which creates unhygienic conditions and contaminates groundwater resources.  

Unknowingly, many people are using the wastewater generated by others for drinking, because of towns and cities upstream discharging their wastewater to rivers that are the water source for people downstream. There is also a stigma against people using treated wastewater for domestic purposes.  

I have been involved in work that aims to address these problems. The solution is for the wastewater generated to be treated to drinking water level. It is then stored in lakes, before being pumped and treated again so that it can be used as drinking water.  

We have taken all measures necessary to avoid any risks associated with this treatment, and we believe this is a model that could be easily replicated.  

This system enables water bodies to be clean, enhances groundwater recharge, and provides a reliable source of water, while protecting the environment. 

Professor Akiça Bahri, Board / Advisory Committee member with UNU-INEWH, IRC and IWMI 

In Africa, 779 million people do not have sanitation services sufficient to ensure their waste is safely handled and treated, or reused/disposed of in a safe manner. Faecal sludge and wastewater management are, therefore, a priority.  

Africa could become a pioneer in resource recovery and reuse thanks to integrated, socio-technical solutions, based on local situations and knowledge. Options include:  

  • Innovation in technology and social acceptance such as the nature-based solutions for wastewater treatment used in Northern Uganda, and the Bill & Melinda Gates Foundation Transformative Technology Portfolio and the Generation 2 Reinvented Toilet that is field tested in people’s homes in South Africa. 
  • Innovation in the sanitation economy with various companies embracing the sanitation economy. This includes Firmenich, which is making toilets more appealing by using effective malodour control. 
  • Innovation in the organisation of services and governance with a number of institutions involved in the agricultural reuse of wastewater for fruit trees in Ouardanine, Tunisia, which recovers part of the operation and maintenance costs of irrigation. 
  • Innovation in financing models with public-private partnerships (PPP) using a mixture of financing opportunities to reclaim water for industrial purposes under a PPP agreement in Durban, South Africa. 
  • Innovation in policy, institutional, and regulatory frameworks with a systems approach making water reuse a long-term strategy in water resources management in the Seychelles under an integrated and comprehensive sanitation master plan. 

The promotion of such innovations in Africa requires multi-level and multifaceted efforts. There is a need to foster partnerships with industrial operators to overcome barriers to the diffusion of knowledge. City-Wide Inclusive Sanitation is required to provide equitable, inclusive resource planning and management. Kampala, in Uganda, provides a good example of a city that is working towards city-wide sustainability that builds resilience to climate change. 

Professor Stuart Khan, School of Civil & Environmental Engineering, University of New South Wales, Australia 

In my presentation, I focused on progress in the development of purified recycled water in Australian cities. I highlighted some of the technical methods that have been developed and applied to assess the public health risks associated with potential exposure to hazardous chemical substances and pathogenic microorganisms.  

In this regard, the use of quantitative chemical risk assessment and quantitative microbial risk assessment have been very important. Nonetheless, there are challenges associated with data gaps and other types of knowledge gaps. For instance, there is not exhaustive data available on all types of chemical substances that may be present in wastewater, or quantitative information about their removal by all water treatment technologies operating under all possible treatment conditions. 

Scientific research is playing an important role in addressing these data gaps by improving our understanding of the fundamental properties of contaminants, which render them more or less susceptible to removal by various treatment processes and conditions. With this understanding, it is possible to ‘group’ contaminants according to their expected removal performance without the need for direct analytical data for each contaminant. Robust methods for applying this grouping, and incorporating residual uncertainty, will greatly aid risk assessments for purified recycled water projects. 

The drivers to expand the use of purified recycled water in Australia are significant and growing. One driver is population growth, particularly in large established cities, such as Sydney, Melbourne, Brisbane, Perth, Canberra and Adelaide. These increasing populations produce greater demand for high-quality drinking water.  

Another driver is climate change, particularly with regard to increasingly severe drought. Even without significant changes in long-term average rainfall, some cities could become more exposed to severe multi-year droughts, producing significant water shortages. To help mitigate these shortages, Australian cities are considering the need to increase the proportions of demand that can be met by rainfall-independent water supplies. Seawater desalination and purified recycled water options are being pursued as future alternatives. 

Professor Kwang-Ho Choo, Department of Environmental Engineering, Kyungpook National University, Korea 

In my presentation, I focused on the challenge of removing hazardous organic contaminants from industrial wastewater effluents, including 1,4-dioxane, dyes, and perfluoroalkyl substances (PFAS), which are known to be resistant to conventional treatment methods. These substances pose a significant concern because of their stability, making eliminating them through conventional biological treatment processes difficult. Some contaminants can even pass through dense reverse osmosis membranes typically employed for water reuse. 

Various alternative approaches have been explored, including carbon adsorption and advanced oxidation processes. These processes, such as ultraviolet (UV) photolysis, UV/H2O2, solar photolysis, solar/H2O2, O3, and O3/H2O2, have shown promising results in removing hazardous substances from wastewater. However, they also present new challenges, such as waste generation, chemical requirements, and the formation of toxic by-products.  

Another area of interest in wastewater reclamation is electrochemical processes, which have gained attention for their ability to generate various oxidising agents on site by adjusting electrical power. 

In light of these considerations, I have developed and investigated an innovative technology called electrocatalytic membrane technology. This technology uses electrocatalytic microfilters, which are created using hydrothermal and coating processes. These microfilters demonstrate potential for the degradation of persistent organic matter, such as 1,4-dioxane and PFAS, and can separate particulate matter effectively from wastewater effluent. Additionally, the electrocatalytic microfilter removes chemical oxygen demand and inactivates bacteria, enhancing the overall purification process. 

My work has demonstrated the promising prospects for electrocatalytic membrane filtration as a viable solution for purifying industrial wastewater effluent in water reuse applications. Furthermore, it highlights the importance of developing advanced treatment technologies, particularly novel membrane technologies, to eliminate dissolved and particulate contaminants simultaneously.