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Industrial wastewater: a liability or an asset
Written by Brandon Lee, Research and development engineer at Kurita R&D Asia, who previously worked in Sembcorp-NUS corporate laboratories. Edited by Ismail Weiliang.
ISMAIL WEILIANG
The Climatebender
BRANDON LEE
Research Engineer
Views are entirely ours
and not connected to any company
An Asset or Liability?
According to research and markets, the global water and wastewater industry is projected to grow by 5.3% to $806.14 billion in 2022 [1]. Of which is it estimated that industrial wastewater would account for roughly 40% of that sector. In the ‘grey’ era, industrial wastewater is conventionally treated as a waste product; hence disposal has always been a priority. Moving into the ‘green’ era, there is a shift in mindset of industrial wastewater from waste to potential resource valuable to various industries. Increasingly there is growing interest for water reuse with resource recovery from industrial wastewater in Singapore. Recent grant calls from PUB [2] demonstrates Singapore’s focus in mindset. This is similarly echoed by JTC’s waste to resource incentive program and Zero liquid discharge (ZLD) for industrial wastewater program [3].
A Step Forward, A Step Change
The change in mindset is a step forward for greater progression into a new cleaner and greener era. Research institutes and water companies like Kurita™ are heavily invested in innovating new commercial solutions for industrial wastewater treatment and recovery. Both minimal liquid discharge (MLD) or zero liquid discharge (ZLD) focus on extracting clean water for reuse from wastewater. This brings potential benefits like reduction in solid waste disposal cost, enhancing water recovery and also recovery of valuable materials [4]. ZLD product is solid waste while MLD product is a concentrated brine. Further downstream treatment with Multi-component concentrated streams found in MLD processes can be done to recover precious materials [5]. ZLD may be an ambitious goal due to high cost from heating and hence MLD may be a smaller step for industries to work towards. Towards the green era, both industries and government agencies are looking at such commercial solutions.
MLD / ZLD
MLD/ ZLD solutions generally consist of stages, and at each stage fresh water is extracted. Membrane processes consist of processes such as electrodialysis (ED), forward osmosis (FO) and reverse osmosis (RO) with ED/EDR and FO having more resilience to high fouling wastewater. The concentrate brines from membrane processes are passed on to concentrators for further processing. Concentrators generally consist of thermal processes that further concentrate brine, where membrane processes are deemed not economical or are physically limited. Thermal processes such as evaporators or membrane distillation (MD) are most commonly utilised. Crystallisation further vapourises remaining water in the concentrated brine to produce solid waste for disposal or the recovery of precious materials. At every stage of treatment, fresh water is removed and waste volume is reduced considerably. However, the cost of operations increases exponentially with succesive stages of treatment, with crystallisation having the highest unit cost of operation.
Challenges
The key issue is still on the cost effectiveness of such solution against the benefits it brings. In order for successful implementation of ZLD/MLD solutions, it is important to evaluate the efficacy and the benefits it brings. The selection of type of processes highly dependent on the feed water characteristic of the industrial wastewater. It is hence important to consider operation cost, capital cost for the the long-term and short-term horizon. There is no one-size-fits all solution and hence requires integration expertise for successful implementation. Companies like Kurita™ group has the domain expertise in the water field, with a large portfolio of products, services, water treatment chemicals, water treatment facilities, and maintenance services. This enables us to integrate system and customise solutions based on the customer’s needs.
An asset for the green era
To wrap up, industrial wastewater should not be viewed as a liability, rather as an asset. In the green era, industrial wastewater should be viewed as an asset due to commercial advantage of ‘net-zero’ in this sector. Reduction in waste disposal cost, recovery of valuable salts/ concentrated brines etc are amongst some of the potential benefits these solutions bring. Of course the implementation of such a system requires careful consideration of cost and benefit. MLD/ZLD solutions hence require domain expertise to have practical application.
Authors:
Brandon Lee is an environmental engineer at Kurita R&D Asia. He has a M.Eng. (Environmental engineer) and a B.Eng. (Environmental engineer) from the National University of Singapore (NUS). His primary role is the research and development of commercial solutions for industrial applications. He works on membrane and membrane related projects serving clients within the Asia Pacific region. His speciality is on industrial wastewater treatment and process integration.
Ismail Weiliang is a climate resilience consultant with over half a decade of experience and specialises in flood risk advisory for Asia. His work involves advising governments and development banks on strategies to transform climate risks into resilience. He also founded “The Climatebender” a non-profit organisation that provides humanitarian relief to communities vulnerable to the climate crisis.
Reference
[1] Research and Markets, “Global water and wastewater treatment outlook report 2022: Industry is set to grow by 5.3% to $806.14 billion in 2022,” GlobeNewswire News Room, 14-Dec-2021. [Online]. Available: https://www.globenewswire.com/news-release/2021/12/14/2351928/28124/en/Global-Water-and-Wastewater-Treatment-Outlook-Report-2022-Industry-is-Set-to-Grow-by-5-3-to-806-14-Billion-in-2022.html. [Accessed: 01-Feb-2022].
[2] Pub, “Request for proposal (RFP 2101 and 2102),” PUB, Singapore's National Water Agency. [Online]. Available: https://www.pub.gov.sg/globalhydrohub/Pages/RFP2102.aspx. [Accessed: 01-Feb-2022].
[3] C. Chung, “Catalysing industrial transformation for sustainability,” https://www.mnd.gov.sg/docs/default-source/urbansustainability/slides-by-jtc-calvin-chung.pdf. [Online]. Available: https://www.mnd.gov.sg/docs/default-source/urbansustainability/slides-by-jtc-calvin-chung.pdf. [Accessed: 01-Feb-2022].
[4] Muhammad Yaqub and W. Lee, “Zero-liquid discharge (ZLD) technology for Resource Recovery from wastewater: A Review,” Science of The Total Environment, vol. 681, pp. 551–563, 2019.
[5] A. Panagopoulos and K.-J. Haralambous, “Minimal liquid discharge (MLD) and Zero Liquid Discharge (ZLD) strategies for wastewater management and Resource Recovery – analysis, challenges and prospects,” Journal of Environmental Chemical Engineering, vol. 8, no. 5, p. 104418, 2020.
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