The Toveko S-450 filter in the above photograph has been installed to provide tertiary treatment of sewage. Peak design flow rate is 52m 3 /h giving a peak flow velocity through the filter of 11.56m/h.

Inlet suspended solids concentration is 30mg/l and the guaranteed outlet concentration is 10mg/l.

TOVEKO steel filters are only 2.3m high. This means that wastewater from the preceding final settlement tank flows into the filter by gravity, eliminating the need for a pumping station.

The filter control system incorporates automatic level detection in the inlet launder. This level is used to automatically control the stopping and starting of the filter and the sand-washing rate. This reduces the operator intervention required to infrequent checking only.

Since the wastewater arises from a rural area and has a very low chloride content, the filter is constructed in 304 stainless steel. This is the lowest grade available, which means that TOVEKO filters never need painting. The duty / standby wash water pumps were also pre-assembled onto the filter prior to delivery. This means that the installation and commissioning period is very short. On delivery to site, a crane is required to position the filter onto a pre-prepared concrete plinth before connecting:

• Service inlet and outlet pipes
• Dirty wash water discharge pipe
• Electric power to the panel (0.72kW installed in this case)
• Compressed air to panel.

The filter is then ready to be filled with sand and commissioned.