Alpheus designed, financed, built and operates an effluent treatment plant capable of treating up to 1000m3 per day of high strength wastewater from a chicken processing plant.
Client: 2 Sisters
Business: Chicken abattoir and processing Background: The factory is located on the site of an old wartime airbase. Until late 1999, the old sewage works, discharging to a small stream, served as the factory’s wastewater treatment plant for c. 1100 m3/d of effluent. Over the years, various additional plant items were added to cope with increasing loads from the abattoir. The age and complexity of the plant made it difficult to operate successfully and compliance with the final effluent ammonia limit of 15 mg/l was very poor.
Business: Chicken abattoir and processing Background: The factory is located on the site of an old wartime airbase. Until late 1999, the old sewage works, discharging to a small stream, served as the factory’s wastewater treatment plant for c. 1100 m3/d of effluent. Over the years, various additional plant items were added to cope with increasing loads from the abattoir. The age and complexity of the plant made it difficult to operate successfully and compliance with the final effluent ammonia limit of 15 mg/l was very poor.
Contract: Following an initial feasibility study, a 3-year operating contract was signed in September 1994, taking on existing site labour. The contract was extended by a year and, in 1999, a new BOOT (Build, Own, Operate, Transfer) contract was agreed whereby most plant elements were replaced by new equipment under a scheme financed by Alpheus over a 10-year period. All costs associated with the plant are now the responsibility of Alpheus, transferring process and commercial risk from Buxted.
Process: When Alpheus took over the plant operation, the plant comprised inlet screen, 3 small balance tanks, DAF (dissolved air flotation) plant, followed by a flow split to the old trickling filter plant and to a small activated sludge plant. During the initial contract period, a nitrifying biotower was added to improve ammonia reduction in the final effluent (see graph overleaf). In 1999, the entire works apart from the DAF plant was replaced to comprise a much simpler process of: new inlet works and screening, balance tank, DAF plant, and activated sludge plant incorporating anoxic selector tank. As fail-safes, the old final clarifier was retained in case of settlement problems and the old activated sludge plant was converted to an emergency holding lagoon. Plant Features: The new plant was designed with lifecycle costs and health and safety as fundamental considerations.
Features include:
- Improved access to reduce health and safety risk
- Designing-out of confined spaces
- Overpumping connections and gravity overflows
- Full operating and emergency procedures
- “Tank within a tank” construction to reduce civils cost
- Dual power supply for operational security
- Anoxic selector tank to reduce oxygen demand
- Use of existing tanks as emergency overflow tanks
- Standardisation of pumps to reduce spares inventory and allow easy maintenance
- Localised isolators
- Plant labelled with detailed asset register
- External panel controls
- Automated and PLC-controlled plant with telemetry to reduce security labour
Achievements: Continual improvement in the final effluent quality; particularly in terms of ammonia as shown in the graph below:
