|ABATTOIR WASTEWATER – DISCHARGE TO A RIVER|
Micromac was asked by an abattoir processing 1,200 cattle and 3,000 sheep per week to design a completely new treatment system for all their wastewater. At the time, all the wastewater was tankered from the site. Not only was this expensive, with costs constantly increasing, but the lorry movements had a negative impact on the local area. Space on site was very limited, and any system had to be designed to fit.
A river runs near the abattoir site and offered the opportunity for disposal of the wastewater. Because of the sensitive nature of the river, the consent for discharge granted by the Environment Agency was demanding:
ammoniacal nitrogen < 10 mg/l
suspended solids < 15 mg/l
BOD < 15 mg/l
pH 6 – 9
The abattoir was producing over 100 tonnes of wastewater per day, comprising lairage washdown and general wastewater. The mix was high in ammonia, BOD and suspended solids, and the condition of the wastewater was highly variable. This presented a heavily loaded wastewater which was very demanding to treat.
Micromac’s solution was a system designed specifically to meet this loading, which would not only achieve the Environment Agency’s consent, but also fit into the limited space available. The new system comprised a balance tank with Helixor mixing; a Dissolved Air Flotation unit; an Activated Sludge System; Clarifier and additional treatment using Submerged Aerated Filters, and a Rotating Drum Microscreen. The final stage was a V-Notch with a monitoring system, so that any out-of-specification treated wastewater could be diverted for re-treatment before final discharge to the river. The system is designed so that it can be operated and maintained by the on-site maintenance engineer.
An important feature of this system is the continuous measurement of the treated wastewater, so that there is absolutely no possibility of any discharge outside the consent. The system therefore continually achieves its consent to discharge set by the Environment Agency.
The new system saved the company over £200,000 per annum on tanker charges; tanker movements through the local area have been substantially reduced, and the system is both robust and reliable. Both the local area and the abattoir itself gained positive environmental benefit, and the system is operating well within its capacity – providing for business growth for years to come.