How to recover coal and treat runoff pond effluent?

The Challenge

The Client had a need to treat and discharge coal pile runoff water containing high amounts of total suspended solids from its facility.

The Client had tried in the past several other technologies such as conventional clarification, DAF & compressible sponge-like media filters, developed by Veolia’s competition with no satisfying result.

It led the Client to first contract Veolia for a four week pilot demonstration of the high-rate, sand ballasted clarification process, ACTIFLO®, to demonstrate the overall system performance with regards to the desired effluent quality (TSS <30 mg/l and/or < 20 NTU with inlet of 100 – 1000 mg/l TSS and particles distribution of 0.5 – 10 micron in inlet ) and to confirm full-scale design parameters.

A year later the client experienced a significant rainfall. They had 13 inches in a month compared to their average of 4 inches which caused the level in the coal pile runoff pond, usually maintained by evaporation rates, to rise up to the spillway.

The Solution

The Client contracted Veolia for the rental of an ACTIFLO® TURBO trailer (capable of 1200+ GPM) coupled with Hydrex™ chemicals. Veolia was also awarded an operations contract, offering the Client a hands-off approach.

Key to the overall success of the project, Hydrex™ chemicals supplied a blend of two coagulants and a flocculant / polymer needed with the microsand.

Results

Veolia treated over 50 million gallons of water in clarification mode; at instantaneous flows of 500 – 1000 GPM. The pilot indicated rise rates > 40 GPM/ ft2 were achievable; however, in the full-scale, the client did not have a feed pump big enough to provide more than 30 GPM/ ft2 ~ 1000 GPM. 

The cost of treatment using ACTIFLO® rental, Hydrex™ chemicals and the operations, was similar to typical sewer rates in the US.