Preconcept study for the evaluation of phosphorus removal technologies for sewage of a paper (LA12)

ISSUE

A sludge treatment plant operated by City of Quebec has a series of band filters to desaturate the sludge. Sludge tends to foul the filter cloth, it is cleaned continuously after unloading the cake. This washing is done using large jet of water, which consumes nearly 100 m3 / h of water. Given the flow, the treatment plant is forced to use groundwater to meet this need.

The pumped water is then stored first in a huge tank before being sent to the filters to wash the canvases . However, the employees of the station realized that despite the intense washing of the canvases, they were clogging rather quickly which led to significant maintenance costs. An internal investigation then revealed that the washing water was loaded with colloidal particles of iron oxide clogging the filter cloth instead of washing. This investigation also revealed that these particles would form in the storage tank as a result of the interaction between the oxygen in the air and the large dissolved iron load contained in the groundwater. Since the station can not change wash water sources, it has asked STS Canada to help identify the best filtration technology to remove iron particles from the tank.

TECHNOLOGICAL CHALLENGE

The challenge of this project was to treat a large flow of water containing a large amount of very fine particles difficult to filter.

RECOMMENDED SOLUTION

After analyzing the groundwater characteristics, STS Canada proposed using an adjuvant to prevent iron precipitation in the reservoir. In this way, the water would not need to be filtered before being used as wash water for the band filters.

RESULTS

As a result of the STS Canada adjuvant being used by the sludge treatment plant, precipitation of the iron could have been prevented in the storage tank. This simple and inexpensive solution has eliminated the problem of clogging of the band filters by iron oxide particles while avoiding an investment of several million dollars for the acquisition of filters that would have been necessary. to the removal of these particles.