AFGRI, a leading agricultural services and food processing company in South Africa
required a new wastewater treatment plant to treat the effluent from one of their
chicken abattoirs.
A lagoon was excavated to treat a flow of 2,500 m3/day using an activated sludge process
Design parameters:
Lagoon dimensions: 57m X 30m X 4.5m with a slope of 1:2.5
Inlet BOD: 150 mg/l
Inlet Ammonia: 120 mg/l
Site elevation: 1,560m above sea level
Challenge
To supply an aeration system suited to the lagoon, with a standard aeration efficiency of more than 2.5 kgO2/kWh and to meet the required effluent quality of BOD<40mg/l and ammonia <5mg/l.
Solution
Four of Mapal’s floating aeration units were installed in the aerated lagoon to supply an oxygen transfer rate of 160 kgO2/hr (SOTR). Each unit included 40 meters of Mapal’s fine bubble diffusers. The floating units received an air flow rate of 2,800m3/hr from a positive displacement blower located next to the lagoon.
Results
The system operates at a power consumption of 60 kWh and continues to deliver high quality effluent and efficient aeration complying with the local regulations. The client ordered another Mapal system for a second site based on the success of the first installation.