CONCEPT FOR WATER SUPPLY OF WASHING BAND FILTERS (LA13)

ISSUE

A sludge treatment plant operated by Quebec City is multiple band filters for sludge dewatering. The filters required frequent washing for cleaning the filter media after unloading the cake as the sludge tends to clog the filter cloth. The washing process requires a large amount of water almost 100 m3 / h of water. With this water consumption and flow rate, the treatment plant needs to use underground water to complete the cleaning process.

The groundwater is pumped and stored in a huge tank, then the water is transferred to the filters to clean the fabrics. However, the plant's employees observed that despite the heavy washing of the fabrics, the filter cloth still has a significant clog up within a short period raising the filter's maintenance cost. An internal investigation revealed that the washing water contained colloidal particles of iron oxide clogging the filter cloth instead of washing it. Moreover, the analysis showed the high Iron content in the groundwater transferred to colloidal particles in the storage. it was the result of the interaction between oxygen in the air and the large dissolved iron load in the groundwater. The plant could not change the wash water sources and requested the STS Canada intervention to identify the best filtration technology to clean the washing water from Iron Oxide particles.

TECHNOLOGICAL CHALLENGE

The vital challenge of this project was the removal of a very small and fine particles in water with a high flow volume and rate.

RECOMMENDED SOLUTION

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

RESULTS

The proposed admixture offered by STS Canada was implemented successfully by the sludge treatment plant and prevent the Iron precipitation in the storage tank. the suggested solution was a cost-effective treatment and made it possible to eliminate the clogging cloth at the band filters due to the iron oxides particles. additionally, the solution avoided an investment of several million dollars for the acquisition of filters which would have been necessary to the removal of these particles.