Antimicrobial resistance: Zero Liquid Discharge can help contain environmental AMR
Within the environmental dimension of antimicrobial resistance (AMR), the point sources of antibiotic pollution include waste from antibiotic manufacturing industries, hospitals, households and farms.
The pharmaceutical sector needs to employ appropriate waste management technologies in order to ensure the elimination of antibiotic residues from the effluents generated. One such waste management technology is Zero Liquid Discharge (ZLD).
ZLD is a water treatment process designed to recover and recycle all the liquid waste from an effluent system.
The focus of a ZLD is to reduce wastewater economically and produce clean water that is suitable for reuse (For example, boilers or cooling towers), thereby saving money and being beneficial to the environment.
ZLD systems employ advanced wastewater/desalination treatment technologies to purify and recycle all of the wastewater produced. ZLD technologies also help industries meet discharge and water reuse requirements, enabling businesses to:
- Meet stringent government discharge regulations
- Reach higher water recovery
- Treat and recover valuable materials from the wastewater streams
The conventional methods to reach ZLD uses technologies such as evaporators, multi-stage flash, multi-effect distillation, mechanical vapour compression and crystallisers.
ZLD technology includes pre-treatment and evaporation of the industrial effluent until the dissolved solids precipitate as crystals. These crystals are removed and dewatered with a filter press or a centrifuge. The water vapour from evaporation is condensed and returned to the process.
In the last decades, though, there has been an effort from the water treatment industry to revolutionise high water recovery and ZLD technologies. This has led to adoption of processes like electrodialysis, forward osmosis and membrane distillation.
A success story
A pharmaceutical company in Gujarat designed a ZLD unit to remove antibiotics from manufacturing wastewater.
This investment was necessary as the government-approved Central Effluent Treatment Plant was already at full capacity and could not receive liquid discharge from the company’s effluent treatment.
To design an effective ZLD, the company formed a cross-functional team consisting of internal planning, manufacturing, engineering and environment Health Safety team and externally certified analytical environment testing laboratory and a consultant.
The work involved performing a mass balance based on all inputs and outputs and the subsequent design included pre-treatment, treatment, reverse osmosis and multiple types of evaporators.
The ability of the company to identify appropriate vendors to establish the design and implement installation and operation of the Effluent Treatment Plant (ETP) were key enablers.
However, analytical testing of the API proved challenging and was not possible. Guidance was received from another lead association involved with AMR to develop the mass balance approach to calculate the antibiotic discharge in their own ETP system instead.
With the ZLD in place, the company was granted an environmental clearance consent after due verification by the authorities with certifications available on record. As a result of designing and operating a ZLD plant, the company is no longer concerned about antibiotics liquid discharge.
Measurement (by electronic flow meter at the inlet of the ETP plant and measurement of the consumption of the treated water in cooling towers / boiler) demonstrates the efficiency of the evaporators, which fully utilise all the treated water.
Industrial water supply is only used when there are excess requirements. Furthermore, installing ZLD reduced the company’s concern related to antibiotic emissions.
The company hopes that these improvements will position the company well in manufacturing supplier tenders, given ‘AMR-compliant’ manufacturing.