Expansion of a distillery wastewater treatment plant in Trinidad & Tobago

This includes:

• Conversion of the existing anaerobic reactor to a CSTR so that reliable anaerobic degradation of pollutants in the wastewater can now take place.  
• The aerobic treatment system has been expanded to include a selector tank and an aeration tank.
• Sand and activated carbon filters have been installed for further wastewater treatment.

THE TASK

The wastewater treatment plant already operated by the client could not meet the required effluent values. CUSS was commissioned to expand the plant and renew it where necessary. In addition to a tender prepared by the client, a visit to the existing plant by a CUSS project engineer was taken as the starting point for the changes made.

Since wastewater from distilleries has very high concentrations of organic material, anaerobic processes are particularly suitable. A CSTR reactor was chosen because they are operationally stable and uncomplicated to operate. For the solid-liquid separation of the anaerobic sludge-water mixture from the reactor, a belt press and a dissolved air flotation system have been installed. The separated sludge is temporarily stored in a sludge tank and then returned to the reactor.

The anaerobic process keeps operating costs low, as no aeration is required and maintenance is low. Furthermore, biological sludge growth and the associated amount of waste is low. The biogas produced is collected in the gas phase of the reactor and then desulphurised and burnt to avoid the emission of climate-damaging gases such as methane. In the future, there will be the option of using the biogas for energy.

The biological load remaining in the wastewater is removed in a downstream aerobic process. This treatment step was optimised with a new selector and aeration tank. In addition, very efficient and quiet rotary lobe compressors were installed.

For further wastewater treatment, a sand filter, a post-aeration system and an activated carbon filter are installed. The required effluent values are reliably achieved.