The next step is to remove the dissolved materials from the water. The plant does this through reverse osmosis (RO) – a pump pushes the liquid against a semi-permeable membrane, so that the smaller water molecules slip through the membrane to form a high-purity “permeate,” and the larger molecules of contaminant stay on the “concentrate” side of the membrane.
The water from the combined ultrafiltration and RO process is pure enough to meet national and international standards for drinking water and can be reused in the food production process.
The team’s work included preliminary process design, budget estimating, inspecting and evaluating existing water and wastewater systems, the final design of the improvements to be made, project management, site construction, commissioning and training support, and ongoing process support and operator training. The new water management system went into operation in 2016.
Pushing the Envelope on Water Recovery
One of the lessons learned was around managing the water stream. The team’s first efforts were around a water recovery system that would recover about 88% of the water for reuse. Although a high recovery, it still meant that 12% of the water went into the brine stream.
There was still room for improvement – squeezing more water from the brine stream. The team decided to use closed-circuit reverse osmosis (CCRO), which recirculates pressurized feedwater until a desired recovery level is reached. CCRO systems achieve recovery by recirculation and can reach any desired recovery percentage in a single stage.
This brought recovery at the plant up to 96%, leaving a much smaller brine stream to be dealt with. It’s now practical to use a mechanical evaporation system to produce from the brine a salt product, which is a saleable commodity into the fertilizer and feed industries.
Water Conservation: Why Getting Good at Water Recovery Matters More Now
The extra effort and capital investment needed to make the food processing plant more efficient in water provides a look at the future. Many industries have been significant users of water, but changing circumstances mean that they need to get good at water conservation.
Partly, this is because changing weather patterns are impacting water supplies, both surface and groundwater, in many parts of the world. And, with a growing global population and rising standards of living, there is more demand for water from domestic as well as industrial uses.
As a result, getting good at water conservation – applying changes to produce the same or greater output while using less water – is becoming more important. At the same time, there’s a growing need to invest in ways to reuse water that would previously have just flowed into the plant’s effluent. And as this example indicates, it’s important to make sure that the recovered water meets high standards for purity.
Providing a production facility, mine or other operation through investing in better water management is part of making it as sustainable as possible, able to deal with changing circumstances such as weather and water supply.
The water conservation initiatives undertaken by the facility in Asia point to a trend that is becoming worldwide. As companies come under stakeholder and regulatory pressure to shrink their environmental footprint, they’re taking a closer look at their water use efficiency. This means that even in “wet” parts of the world, they’re looking into ways to use less water and recirculate what they do use. It’s a good investment in the sustainability of the business and in the sustainability of the planet as a whole.
