Anaerobic Demonstration Plant For The Treatment Of Sugar Wastewater

Facts on our local Sugar Industry

  • The sugar industry is the oldest and largest agro-based industry in Jamaica. It plays a major social and economic role in the Jamaican society.
  • Currently there are eight (8) sugar factories operating on the island.
  • The industry provides employment for over 50,000 people and is the third largest earner of foreign exchange.
  • Each sugar production year a total of approximately 45 million cubic metres of wastewater is produced.
  • The sugar industry is the largest single source of organic effluent pollution in Jamaica.
  • A total of up to 30,000 tonnes *COD/ annum is released to the environment.

*COD – Chemical Oxygen Demand – a measure of the pollution load.

CHARACTERISTICS OF SUGAR WASTEWATER

COD 450 mg/l (ave). range 200 – 2000 mg/l
Temperature 33 degrees celsius (ave). range 29 – 38 degrees celsius
pH range 6.0 – 7.0
Nitrate 4.0 mg/l (ave). range (0.5 – 7.5)
Phosphate 0.58 mg/l (ave). range (0.47 – 0.68)
Conductivity 1.2 mS/cm ave
BOD/COD approximately 0.5

Anaerobic Treatment
Sugar wastewater is classified as a low strength wastewater due to the fact that the COD concentration is below 3g/l. The effluent leaving the factories have a high quantity of floating matter as well as suspended matter. Compared to other wastewaters, sugar wastewater is easily biologically degraded. For the crop year 1997/98 a 500 cubic metres Upflow Anaerobic Sludge Bed (UASB) reactor was operated at one of the island’s sugar factories and showed COD reduction of over 70%. Suspended solids in treated effluent showed very low values. The reactor was operated at a minimum hydraulic retention time (HRT) of 10 hrs, a 115 litre pilot plant was also operated and showed COD reduction of approximately 80% operating at 8 hrs. HRT. For the treatment of sugar wastewater anaerobically, HRT as low as 6 hrs. can be applied.

Advantages of Anaerobic Treatment

  • Capital Costs lower than conventional aerobic treatment
  • Operation and maintenance costs lower than aerobic treatment
  • Process control much simpler when compared to other methods of treatment
  • Tropical climate ideal for the anaerobic process
  • Production of energy source (Biogas)

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