Industries are seizing the benefits of water reuse. Following a recent IWA webinar, The Source looks at this increasing focus on the circular economy.
Water scarcity and environmental degradation are driving water reuse projects across the world. IWA recently hosted a webinar on reuse for industrial purposes, with a focus on emerging economies in Africa and Asia. This is part of a series of webinars also exploring reuse for drinking water and industrial applications in advanced economies.
After agriculture, industry is the second largest water consumer, generating 25% of all wastewater effluents. The demand for water and its disposal can have catastrophic impacts on water resources and the environment. With industrial activity rising, water reuse provides an important part of the solution towards long-term water security and economic prosperity.
Addressing delegates at the recent IWA webinar, Josef Lahnsteiner, technical research and development director of the WABAG Group and Chair of the IWA Water Reuse Specialist Group, explained that water shortages are the most immediate driver for industries to engage in water reuse. Brand protection is also a factor, with industrial users eager to negate the financial damage and reputational risk of a production facility being forced to shut down because of water shortages.
Reclaimed water is also generally cheaper than municipal supplies, in part due to wastewater discharge fees, policies and regulations.
Dr Nupur Bahadur, head of the Centre of Excellence on Water Reuse at the Energy and Resource Institute, New Delhi, and Vice Chair of IWA India, provided further context on how reuse is a response to the water risks faced by an industry driven by an ever-increasing demand for water.
Bahadur drew attention to the fact that in water stressed areas in India industrial supply is often cut to ensure that water security is maintained. She referred to the importance of policies, including the Zero Liquid Discharge (ZLD) compliance set by the Central Pollution Control Board of India requiring industries to treat water to standards fit for reuse – standards specified within a National Framework for Safe Reuse of Treated Wastewater. Government policies are the main driver for water reuse in India, as most funding for reuse comes from central government.
Industrial reuse scenarios
Several detailed case studies were presented within two main supply scenarios: reusing industrial effluents in industry; and treating municipal wastewater for use in industry. Effluent sources and industrial quality requirements have major implications for reuse processes, good practice measures, and commercial models.
Indian Oil Corporation (IOCL) Refinery in Paradip, Odisha
The largest water recycling plant in India, the Paradip plant recycles 54 MLD from the refinery complex, achieving 75% water recovery. Source water is composed of several effluent streams including oily water, contaminated rainwater, sour water, blow-down water, spent caustic, landfill leachate, and sanitary wastewater. These are kept segregated upon entering the recycling plant and treated separately in an Effluent Treatment Plant (ETP) and a Tertiary Treatment Plant (TTP).
Balkrishna Industries in Gujarat, India
This example demonstrates how reuse from multiple industries can be achieved. Three different water intensive manufacturing plants generate liquid wastewater, steam condensate, and blow-off water. These same plants are supplied with recycled water, reducing their dependence on raw water. Bahadur highlighted the success of regular reviews and monitoring, which enables the site to reduce leakage and optimise use of the recycled water.
Surat Municipal Corporation, India
This is a high-profile example of a reuse scenario, recycling domestic wastewater for industrial purposes. The plant treats 970 MLD domestic wastewater and generates 319 MLD. Of this, 160 MLD is supplied to textile clusters, 112 MLD supplies other industries, 28 MLD goes to agriculture, and the rest is used for various environmental purposes. The annual revenue of $18.3 million exceeds the annual Operational and Maintenance (O&M) costs of $14.4 million, demonstrating that it is possible to cover 100% of O&M costs from revenue.
Mathura Refinery, India
This example illustrates an alternative cost model. This project was the first One City project and shows how it is possible to integrate industrial water use and river conservation. The critical point in terms of financing reuse and environmental management is that 20 MLD is supplied to the Mathura Refinery, the revenue from which covers the O&M costs. This project represents an important example of the Public-Private-Partnership (PPP) model in the country.
Ujams wastewater treatment, Namibia
The Ujams wastewater treatment company operates the Ujams treatment plant according to a build, own, operate and transfer (BOOT) contract with the city of Windhoek. An original treatment plant was unable to meet the city’s discharge requirements and so a new plant was built to meet specifications to discharge into the Klein Windhoek River. It now supports the rehabilitation of the upper watershed using industrial water.
James Villet, Ujams’ plant manager, described the treatment processes in detail during the webinar. He noted that because the plant processes industrial wastewater from sites with varying production periods it must deal with periods of very high and very low pH, and that this is stabilised by hydrochloric acid or sodium hydroxide dosing.
The other crucial issue is the high cost of ultrafiltration membranes. Villet explained how the plant minimises expenditure via weekly tandem sodium hypochloride and citric acid maintenance cleans – the chloride to crystalise the high levels of total dissolved solids (TDS), and the acid to prevent crystals clogging the membranes. This is supplemented with two annual recovery cleans in which the whole process is switched off to allow for longer dosing that recovers membrane performance. The plant is eight years old and production averages 92% of design capacity. The design accommodates sludge retention of 12 days, and the plant typically runs at eight to 10 days, providing a further benefit to the maintenance of the membranes. The city contract states coliforms must be less than 200 CFU/ml. The plant exceeds that requirement, delivering less than 1 CFU/ml.
Dr Bahadur concluded by recognising that, despite the treatment and compliance levels, many industrial sites in India are still unable to achieve ZLD. She stated that these difficulties are due to a lack of sufficient knowledge of the science and technology used for water treatment. She stated: “The same kind of protocols are used to treat all kinds of water.” The reliance on membranes to treat colour, chemical oxygen demand (COD), and toxicity, sludge, and low biodegradability means fouling remains a huge problem. This is compounded by the subsequent energy and resource intensive treatment required to achieve ZLD.
To overcome these problems and make ZLD and reuse sustainable, affordable, acceptable and compliant, researchers at The Energy and Resources Institute have developed ‘TERI advanced oxidation technology’ (TADOX), which uses photocatalysis in secondary treatment. This new process uses UV light and radiation, which oxidises the molecules and breaks the chemical bonds of pollutants.
Lab and campus results show the technology is applicable to a large range of industrial wastewaters, including industrial wastewaters from the textile industry, oil and gas, pharmaceuticals and concentrate from Multiple Effect Evaporators (MEE). TADOX can be retrofitted into pre- or post-biological treatment or polishing stages. Further disinfection is not required, providing flexibility to bypass biological treatment and reduce energy, resources, and treatment times significantly. Initial results after applying TADOX to municipal wastewater show effective reductions in physical contaminants, COD, and biological oxygen demand (BOD), meeting the stringent requirements for drinking water and reuse.
Reuse as a commercial enterprise
The Surat and Mathura case studies from India demonstrate that reuse revenues can cover O&M costs. However, Thailand’s WHA Utilities & Power PCL (WHAUP) shows the scope to develop a strong commercial business by providing specialist reuse services and products. Varanon Laosuwan from WHAUP explained how the company has become the sole utilities provider to manufacturers across 11 industrial estates in Thailand and is now expanding its enterprise into Vietnam. At the core of this is the company’s understanding that each industrial estate needs a bespoke design, typically involving multiple treatment systems, recognising the water demands of potential industrial customers and the land area available for natural engineering systems, such as lagoons and wetlands, or traditional grey engineering.
Transitioning previous treatment systems to respond to customers’ pain points within the context of circular economy principles has been fundamental in developing the business. This business model has focused specifically on finding opportunities to add value and generating a demineralised product that can be sold to industries for a premium. This approach does not need government subsidies.
Finding the right buyer is the key to a feasible investment.
It is clear that emerging economies are progressing industrial reuse rapidly in response to growth trajectories, forecast demand for water, and the significant economic risks associated with water scarcity. More research and investment is required to continue developing and implementing reuse and to this end the IWA Water Reuse Specialist Group invites experts to join and contribute to discussions and also to submit papers for the 13th IWA International Conference on Water Reclamation and Reuse set to be held in Chennai on 15-19 January 2023. •
View this webinar at https://iwa-network.org/learn/industrialwaterreuse/