Water treatment company Water Purification Chemical & Plant (WPCP) has completed a water purification plant upgrade project, as mechanical and electrical contractors for State-owned water management entity Umgeni Water, which included a contract to strip existing nonfunctional pressure sand filters and replace these with new coated steel sand filters.

“Owing to the expansion of the population in the greater Ixopo area, in KwaZulu-Natal, the local water purification plant had been experiencing serious water shortages,” says WPCP MD Martin Overy, adding that outdated filtration equipment aggravated the problem and the urgency of the situation required that the upgrade be completed in a three-month period.

He says that the contract entailed the refurbishment of the filtration capacity of the Ixopo Water Purification Works.

Overy explains that the general assumption in the industry is that dirt and suspended solids are trapped in the spaces between the media, which is usually sand. But what actually happens, is the smaller dirt particles are attracted to the larger sand particles by Van der Waals forces, resulting in very clear water, down to less than 0.5 nephelometric turbidity units (NTUs) – the measure of the clarity of a liquid – if operated and backwashed properly.

WPCP, with the assistance of the Umgeni Water plant personnel at Ixopo, process technicians and design engineers at Umgeni Water Process Evaluation Facility (PEF), ensured the contact deadline was met.

“WPCP’s single- and dual- media pressure filters are used for the removal of suspended solids to ensure water is efficiently purified for human consumption, generally down to a turbidity level of less than 0.5 NTU, or effluent disposal down to less than 0.1 parts per million,” says Overy, highlight- ing that the pressure filters efficiently remove materials like iron, manganese, colloids and other precipitates in ground- or surface water.

“Even at fairly high filtration rates – more than 10 m/h – our pressure filters ensure water purification meets the stringent requirements of SANS 241 Class 0, or any SS specification for waste and industrial applications.”

The upgraded plant, with three new pressure filters, now has a filter capacity of two-million litres a day. According to stringent Umgeni Water specifications, the water quantity is 90 m³/h and the quality is less than, or equal to, 0.2 NTU.

Dedicated backwash and back- wash recovery pumps, air blowers, piping and valves, as well as a full set of instrumentation, enhance the new filtration plant.

The plant, which needed to become fully computerised, required automation of the entire pressure filter system, including the design, programming, installation and commissioning of a new motor programmable logic controller and human machine interface data visualisation solutions. This also included valve actuation, pump automation, cabling and the compilation of a functional design specification for the system.

This equipment was supplied by Electron Natal and all process design was undertaken by Umgeni Water’s PEF.