Chongqing Steel is to benefit from a CISDI development which will dramatically improve waste water treatment at its coking plant.

An environmentally-friendly coking waste water rebuild will be carried out by CISDI on an EPC basis.

Cokes at Chongqing Steel are due to increase from 2.80 to 3.20 million tonnes during 2020.

Its current coking waste water treatment system will receive such heavy-polluting desulphurised waste liquids that indicators for treated COD (chemical oxygen demand) and cyanide will be severely affected.

Next year’s waste output is due to be even higher, so it is imperative for Chongqing Steel to take action to rebuild and upgrade its existing treatment system to ensure water meets quality standards and is not hazardous to the environment.

CISDI’s task is to improve the current treatment capacity of 90 to 110 cubic metres an hour and to upgrade existing facilities to meet a safe and stable treated water quality standard.

Surveys have enabled CISDI to identify on-site problems and production data and research results have been combined to find a number of effective solutions.

CISDI plans to add pre-treatment equipment before the existing system for removing oil and cyanide. This will reduce oil content and cyanide concentration in downstream waste water and ensure a stable downstream biological treatment operation.

The CISDI team will also be applying a patented combined process - MBBR (moving bed biofilm reactor) - and activated sludge for the system’s biological treatment, which has no dilution water added and is able to improve the system’s resistance to impact.

This will lay the groundwork for future improvement of discharge standards and may enable a zero liquid discharge target to be achieved.