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Waste Treatment
Increasing interest in ZLD driven by costs and environment
In 2021 the global market for zero liquid discharge ( ZLD ) technology was estimated at $ 1 billion and is forecast to grow at almost 12 % over the next ten years [ 1 ] . The rise is being driven in particular by an increase in adoption of the technology by the food and drink and textile industries as a growing world population puts greater pressure on fresh water supplies .
By Matt Hale , International Sales & Marketing Director , HRS Heat Exchangers
About the author
Matt Hale joined HRS Heat Exchangers as International Sales Manager in 2013 and in 2015 he took on responsibilities for group marketing . Today , he is responsible for overseeing and developing the HRS Group ’ s strategies for business development and marketing . Matt has a proven background of over 20 years within process and mechanical engineering and holds a Sales & Marketing Management Diploma from the Ashridge Business School .
Zero liquid discharge ( ZLD ) is a liquid waste stream treatment which involves transforming liquid waste streams into clean water ( which can be reused ) and a minimum volume of solid residues . One of the advantages of ZLD over other treatment techniques is its theoretical ability to separate unwanted materials from water , whether they are benign , hazardous or toxic . The resulting solid residue is often more stable , making it suitable for recycling or landfill . However , poor management or handling of the remaining residue can result in unintended environmental consequences . For example , storage ponds may leak or affect local wildlife while there is the potential for toxic chemicals to leach into groundwater from landfill . It is therefore important that when implementing a ZLD system , full consideration is given to the entire process , including the ultimate fate of liquid and ( semi- ) solid waste streams . A well-designed ZLD system should minimise or even eliminate liquid waste streams , resulting in clean water for reuse or environmentally-friendly discharge , and a solid residue suitable for further processing ( often to recover valuable components for use elsewhere ) or for safe disposal .
The factors driving ZLD uptake According to Transparency Market Research1 , ZLD is being implemented across a wide range of industries , including chemical and petrochemical production , food and drink production , textiles , energy and power , and pharmaceutical manufacturing . These industries are being driven to adopt the technology due to growing environmental awareness of the hazards of toxic wastewater and increasing environmental regulation . In turn this has increased the costs of handling and disposing of such waste streams , and in some cases has made such disposal impossible . As a result , companies are looking for more sustainable alternatives , and ZLD is one of the leading technologies in this area . The specific factors driving uptake are different for each industry . For example , in the energy and power sector ( historically the largest user of ZLD technologies ), access to clean water suppliers is an increasing concern . Pollution control is also a major driver , and the US EPA considers zero discharge as the preferred treatment option for fly ash and bottom ash transport water , and wastewater from flue gas mercury control systems [ 2 ] . Elsewhere , growing awareness of the toxic effects of petrochemicals and petrochemical waste products is
HRS has installed ZLD systems for clients in Europe . Image courtesy of HRS Heat Exchangers .
driving efforts by the industry to clean up its waste processing systems . ZLD methods are already widely used in industrial wastewater treatment to recover useable and profitable minerals and by-products from waste streams , and the success of such systems is encouraging their take up by other businesses . In 2015 the Indian government issued a draft policy requiring all textile plants generating more than 25 cu . m . of wastewater effluent a day to install ZLD facilities [ 2 ] . ZLD technology has been utilised in various markets around the world , including Europe , Australia , Canada , the Middle East and Mexico , but the biggest markets , and the biggest potential for expansion , can be found in the United States , China and India [ 2 ] .
The benefits and challenges of ZLD In general terms , the use of ZLD reduces water pollution and augments water supply , but this is sometimes offset by high costs and energy consumption and in the past these factors have limited the uptake of the technology . Wastewater reuse minimises the volume and environmental risk of discharged wastewater , but also alleviates the pressures associated with the abstraction of freshwater , but these benefits have to be balanced against the economic and energy costs of implementing ZLD systems . As water scarcity and environmental pollution around the world intensifies , ZLD becomes more feasible and widespread , and the relative costs of ZLD technology versus the alternatives ( assuming alternatives even exist ) are lowered .
50 Heat Exchanger World February 2024 www . heat-exchanger-world . com