A water treatment plant built at JSE-listed seafood company Sea Harvest’s internationally accredited Saldanha Bay operations, in the Western Cape, treats effluent and seawater and provides all the water the operations require, says Sea Harvest operations director Terence Brown.
“The most important deliverable of the plant is 1.15 Mℓ/d of potable water. This will ensure that there is no disruption to our business, that we remain sustainable and profitable and, importantly, protect jobs.”
Sea Harvest is the single largest employer in the Saldanha Bay municipality, he adds.
The quality of the water produced by the plant meets the drinking water specification of the SANS 241 standard for minimum requirements for potable water.
The quality of the water will be monitored continuously. In addition, the municipality will provide further quality assurance by testing the water to ensure compliance with the required standard.
Sea Harvest’s operations are National Regulator for Compulsory Specifications and European Union-accredited and, to retain this accreditation, stringent food processing requirements include the use of water, highlights Brown.
The fresh fish processing operations, based at the Saldanha Bay harbour, are dependent on municipal water to remain operational. Sea Harvest uses municipal water for factory hygiene, primary and secondary fish processing, human consumption, the washing of bins and tubs, production of ice and fresh water supply to vessels.
“This natural resource is, therefore, a key component of Sea Harvest’s operations,” he says.
The municipal potable water feed to Sea Harvest was reduced by 35% between March 2016 and December 2017 and, as a large water user in the municipality, the risks of a loss of water supply and the associated job losses prompted the company to build the plant.
The water treatment plant, which includes dissolved air flotation, ultrafiltration and seawater reverse osmosis, will replace the municipal water feed by processing factory effluent and sea water as a blended feed, says JSE-listed AECI water and process company ImproChem executive director Sepadi Mohlabeng.
“The first step of the process includes liquid-solid separation by means of mechanical screening, followed by dissolved air flotation. Further fine solids removal will be done by means of ultrafiltration, which also removes dissolved organics. Dissolved solids (salts) are removed through the high-pressure seawater reverse osmosis system to produce potable water.
“With the high energy costs associated with desalination, an energy recovery device is installed. The device reduces power consumption, in kilowatts per cubic metre, by 30% to 50%, depending on the feed source of the water,” explains Mohlabeng.
The plant will supply water to all potable water areas within the factories, including fish processing, cleaning and sanitation, and general use. The costs of the project have not been made public, but the expected return on investment is between five and ten years, based on the current municipal intake and discharge costs, he said.
“The desalination plant was designed, manufactured, built and commissioned within a 16-week period as part of ImproChem’s rapid deployment strategy. This also involved the use of local suppliers,” said Mohlabeng.
“A desalination plant, if designed correctly, is sustainable and cost effective. Such engineered solutions can be built in any area with seawater supply. Further, all secondary waste from water works can be processed similarly. The Potsdam wastewater treatment plant is an example of this sustainable process,” he concluded.