Zero Liquid Discharge Concept and a Few Business Cases
Mr. Ajay Popat
President
Ion Exchange India Limited

Pollution and increased demand have made good quality water scarce and expensive, both in terms of direct cost of water, and the effect of unsuitable water on plant economics and product quality. Meanwhile, disposal norms are getting tighter and their enforcement stricter. The author here explained how to effectively and economically solve water scarcity problems by conserving vast volumes of water and protecting the environment by reducing discharge while generating substantial savings. Four case studies have also been cited to make an analogy.

As per the present scenario, good quality water has become scarce and expensive due to pollution and increased demand. The mentioned expensiveness is imparted by the factorials viz direct cost of water, as well as the effect of unsuitable water on plant economics and product quality. Meanwhile , disposal norms are getting tighter and their enforcement stricter. Ion Exchange's effluent recycle solutions are integrated to yield optimal benefits. For instance, recycle systems are combined with specialty water treatment chemical programs that substantially reduce water discharge (for example, cooling tower blowdown); and state-of-the-art effluent treatment plants are integrated with Zero Liquid Discharge (ZLD) processes. These are backed by comprehensive operation and maintenance services for high performance continuity.

Industries that have installed our effluent treatment, recycle and ZLD systems have gained an excellent payback on their investment through:

1) Assured availability of water for process needs as well as low end uses
2) Less requirement of fresh water. Therefore, considerable savings in fresh water costs
3) Additional savings through recovery of valuable by-products for reuse in process
4) Compliance with pollution control regulations and a clean environment through reduced/zero effluent discharge.

Process:

Our ETP/RECYLCE/ZERO LIQUID DISCHARGE solutions integrate physiochemical, biological, membranes separation process, and multiple effective evaporators for optimum water recovery.

Based on the effluent characteristics, we customize various treatment process and equipments. Thus we offer a wide range of process separation equipments to remove different levels of contaminants like oils, suspended solids etc in the physiochemical process. Depending on the type of organic contaminants we offer the widest range of anaerobic and aerobic processes. For recovery of treated effluent, our range of membrane processes include ultrafiltration, nanofiltration, reverse osmosis (spiral, disc, and tube RO ). To treat RO rejects and enhance further recovery of water, we offer a wide range of evaporators. The concept is integrated with complete solid waste management process that includes dewatering equipments.

Our ZLD systems have been installed in almost all industries. A partial list of some complex liquid waste we have treated to a level of zero liquid discharge include:
  • A refinery at Jamnagar (Gujarat, India) installed a water treatment plant that is designed to contain and treat all internal process/utility waste water and storm/fire water, with the objective of zero liquid discharge.
  • A leading fertilizer company in North India has installed a recycling plant - design capacity 128 m3/h. Cooling tower blowdown and regenerate waste from the demineralization plant are recycled and reused in process.
  • A leading integrated steel manufacturer has implemented a series of near ZLD projects with the objective of reducing water conservation per tonne of steel produced to enhance their competitiveness through reduce water footprint.
Some case studies are given below:
Case Study 1:
Ion Exchange has supplied a state-of-theart ZLD plant for a cement manufacturer in Gujarat. The plant was successfully commissioned in the year 2009 and is in operation since then. The total effluent generated from the utility department of the power plant, is about 500 m3/day. This includes blow down from cooling towers, reject/effluent from softeners, DM plant, and pressure sand filters.

A sharp decline in the water levels of the region and an overall environmental consciousness led the company to set up the first plant of its type in their group, enabling them to achieve their vision for water conservation and zero discharge.

To treat the effluents, Ion Exchange recommended & implemented a scheme that includes extensive pretreatment of water, Indion Ultra filtration (UF) followed by two-stage Indion Reverse Osmosis (RO) and finally evaporation to handle the reject from the membrane systems. The plant, thus, recovers 85 percent of the waste water for reuse and achieves zero discharge. At the same time it helps conserve water by reducing fresh water intake through this recycling program.



Case Study 2

Ion Exchange has supplied a state-of-the-art ZLD plant for on EPC basis along with O & M for a synthetic rubber manufacturing facility in North India.



This is designed to treat 3000 m3/day of complex effluent generated by process with a treatment scheme, which includes physico chemical process and two stage biological process followed by state of the art membrane process consisting of Indion Ultra Filtration (UF), Indion Reverse Osmosis (RO), and finally evaporation (MEE) to handle the rejects from membrane systems. The plant, thus, recovers 91 percent of the waste water for reuse and achieves zero discharge.

Case Study 3

Ion Exchange has supplied a ZLD plant for a major synthetic fiber & polyester manufacturing plant in Gujarat.



This ZLD plant is designed to treat 50 m3/hr of waste water, with a treatment scheme, which includes Indion HRSCC, followed by Indion Ultra filtration (UF), two stage Indion Reverse Osmosis (RO) and finally evaporation (Multi effect evaporator) to handle the rejects from membrane systems. The plant, thus, recovers 90 percent of the waste water for reuse and achieves zero discharge.

Case Study 4

Ion Exchange executed a very large ZLD project for a large automotive manufacturing company which also included a water treatment plant for industrial and potable water supply, domestic sewage treatment systems using advanced Membrane Bioreactor (MBR) technology apart from dedicated facilities for water and sewage treatment plants for the company's township thus creating a world-class 'Water Complex' at the customer's location.



Conclusion: The Ion Exchange ZLD systems provide numerous economic and environmental advantages wherein water is recycled and reused, accruing savings on the cost and treatment of raw water. Since all water is reclaimed, no effluent is discharged from the plant, minimizing the environmental impact of industrial activity.