Innovative bottom sludge scraper put to use in Ivanovo

A rotating bottom sludge scraper based on a completely new design has been in operation in the Russian city of Ivanovo since October 2012. The design has proved very successful, with only a few adjustments required.

Ivanovo case

The challenge
The previous system used at Ivanovo’s waste water treatment plant featured a conventional sludge scraper with a wheeled bridge that moved around the tank. This set-up often suffered operational malfunctions, especially during the winter. The equipment, which had reached the end of its useful life, was evaluated and specifications were drawn up regarding the improvements to be achieved with the solution brought in to replace it. The most important requirements were to continue using the existing tank and to reduce servicing and maintenance.

The solution
After examining the different options available, the decision was taken to carry out a pilot installation in one of the plant’s four 40-metre tanks. The intention was to try out a completely new design for round tanks – Nordic Water’s Z3700 Rotating Bottom Sludge Scraper. Instead of a conventional bridge and drive unit in the middle of the tank, a central frame rotates around the structure in the centre of the tank. This frame, which is specially adapted for each individual tank, is supported and guided by sliding units. The scraping unit is fixed to the centre and the frame rotates around this. Also included in the equipment is a skimmer.

The result
The installation was straightforward and could be carried out directly in the existing tank without any structural changes. Since there was no bridge or anything else sticking up above the tank, this allowed for a lower profile, making covering the tank a simple and inexpensive matter. The structure’s low weight also makes it easy to handle, as well as reducing both wear and the need to have a perfectly flat surface for the concrete edge, thus keeping servicing and maintenance requirements to a minimum. Compared with the previous system, this one has needed much less servicing and maintenance despite collecting the same amount of sludge and retaining the same high water quality. Following a few minor adjustments to the sensor and the speed, the system has been working extremely well. The solution has proved robust and reliable and makes a strong case for itself as an option for replacing the scrapers in the three remaining primary sedimentation tanks.

Technical data
– 408,000 inhabitants
– Four round primary sedimentation tanks with a diameter of 40 m and a depth of 4.35 m
– Capacity: 10,000 m³/h
Installations: three Meva screens, three grit flaps with Zickert grit scrapers, eight secondary
sedimentation tanks (Ø 40 m)

Zickert installation in 2012:
– A Z3700 Zickert Rotating Bottom Sludge Scraper, 40 m
– A bottom scraper arm
– A peripheral surface scraper blade and scum remover

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