A desalination plant installed at JSE-listed sea food company Sea Harvest’s internationally accredited Saldanha factories includes, Dissolved Air Floatation (DAF), Ultra Filtration (UF) and Sea Water Reverse Osmosis (SWRO) systems to treat effluent or sea water, and will provide the company with all the water it requires, said Sea Harvest operations director, Terence Brown, on 22nd March at the launch.
“The most important deliverable of the plant is 1.15 Mℓ of potable water per day. This will ensure that there is no disruption to our business, we remain sustainable and profitable and, importantly, protect jobs.”
The quality of the water produced by the plant will conform to the South African National Standard (SANS 241-1:2015), as the requirement for potable water.
The quality of the water will be monitored continuously through the online plant instrumentation as well as the ImproChem quality management system and as a second tear through Sea Harvest quality management system.
Sea Harvest’s operation is National Regulator for Compulsory Specifications (NRCS) and European Union accredited and, to retain this accreditation, stringent food processing requirements include the use of water.
The fresh fish processing and added value factories, 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, washing bins & tubs, production of ice, and fresh water supply to vessels.
“This natural resource is, therefore, a key component of Sea Harvest’s operations,” he said.
The municipal potable feed to Sea Harvest was reduced by 35% between March 2016 and December 2017. However, as a large water user in the municipality, the risks of a loss of water supply, and the associated jobs, prompted the company to build the plant, said Brown.
The desalination plant will replace the municipal feed and process used factory water and sea water as a blended feed. With all process water now being self-supplied, the water availability to Sea Harvest will now be limited to plant throughput, said ImproChem Engineered Solutions 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 ultra-filtration. This filtration technology will also ensure dissolved organic removal. Finally the dissolved solids (Salts) will be removed through the high pressure Sea Water Reverse Osmosis system to produce potable water.
“With the high energy costs associated with desalination, an Energy Recovery Device (ERD) is installed in the system. This technology reduces the power consumption in terms of kW/m3 by 30% - 50% depending on the feed source of the water, explains Sepadi Mohlabeng.
The plant will supply potable water to the factories, including fish processing, cleaning and sanitation, and general use.
Some of the measures that have been implemented to reduce Sea Harvest’s consumption of water, include the following:
- Installed sea water supply line for our cleaning service provider to connect to the water pump system in order to do initial rinse using sea water;
- Hygiene water pressure increased to reduce the volume required;
- Increased inspections of freshwater lines and reduced the time to do any repairs;
- Daily monitoring and reporting of freshwater consumption in factories;
- Identification of freshwater leaks in facilities and remedial actions carried out ASAP;
- Meetings held with Saldanha Bay Municipality to discuss effectiveness of municipal flow meters;
- Meetings held with key stakeholders, including the Western Cape Premier and Saldanha Bay Mayor’s office;
- Installed nozzles on freshwater lines to reduce consumption;
- Installation of seawater line to hose down outside areas.