Rubber stamp for Zeon effluent upgrade

ACWa Services Ltd has been awarded a £1.2m turnkey design and build contract from latex manufacturer Zeon Chemicals Europe Ltd to extend the company's effluent treatment system at Sully, South Wales. ACWa's site treatability study demonstrated that a 50-60 per cent reduction in the Chemical Oxygen Demand (COD) of the latex was possible, with the installation of an activated sludge system, modifications to the existing feed supply equipment and dissolved air flotation (DAF) system.

Research study
The new system comprises a fully automated secondary treatment activated sludge system including aeration, degassing, settlement and sludge dewatering stages. This system is fed with effluent from Zeon's existing primary treatment DAF system. The chemical dosing associated with the DAF system is to be fully automated as part of the contract in order to improve the operating efficiency of primary treatment. Also, the feed flow-balancing capacity is to be increased in order to provide a homogenous feed to the DAF system. Combined primary and secondary sludge produced is to be stored in a sludge holding tank and a belt press is then utilised to dewater the sludge (see diagram).

In order to optimise the operation of the existing DAF system, ACWa has implemented various recommendations from the treatability study, including the conversion of the existing small balance tank to a calamity tank, with the raw effluent diverted when pH, flow or load are beyond design parameters. Feed pumps have been installed with inverter drives to allow flow control into the DAF system. The modifications will provide controlled and average flow to aerobic secondary treatment, thereby improving operating efficiency and optimising effluent discharge quality.

Automatic monitoring of the final treated final effluent will be undertaken in a new treated effluent collection tank. Suspended solids and pH monitors are included and an automatic sampler will provide daily composite sampling of the treated effluent for routine analysis. Treated effluent transfer pumps are used to discharge effluent to the existing lagoon.



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