Invercargill City Council Clifton Waste Water Plant has experienced great success with its first NOV Mono EZstrip™ progressing cavity (PC) pump.
So much so, that it is already installing a second unit just six months later.
The plant, commissioned in 1969 for primary treatment, underwent a major upgrade in 1992 to accommodate secondary treatment. In 2003, a third major upgrade saw the building of both maturation ponds and wetlands.
Today, the treatment plant accommodates 50,000 residents and a 30 per cent proportion of trade waste. Inflow to the plant is around 20-25,000m2 per day in dry weather and up to 90,000m2 in wet weather.
The first EZstrip™ transfer pump has replaced one of three Robbins & Myers pumps at the plant. These pump raw sludge from the three primary sedimentation tanks to the digesters for further treatment.
The EZstrip™ pump runs at 182rpm via a 5.5Kw motor and VSD, which allows raw sludge of around 6 per cent of total solids pumped at 20m2 per hour compared with the Robbins & Myers units which pump at around 22-24m2 per hour, depending on the wear of the machines and the thickness of the sludge.
ICC Clifton Waste Water Plants Engineer, Dave Aitken, says the ongoing high costs resulting from maintenance, premature failure and repair costs, along with downtime and high stock inventories to cover breakdowns, were the main reasons leading to the installation of an EZstrip™ Transfer Pump.
"I am very satisfied with the performance of the pump in the first six months we have been using it," he says. "In this time we have had no problems whatsoever and it is a very easy pump to work with. Once a month it is opened to check on any ragging which I am very pleased to say has been clear every time."
"Because we - myself and three operators on site - are so pleased with the operation of the EZstrip™ Transfer Pump, we have already purchased a second which will replace another of the original pumps."