Abstract:
Pharmaceutical industries are now increasing in Bangladesh along with other
industries which are a major polluting industry in Bangladesh. The liquid wastes of
these industries are discharged into nearby natural stream, surface drain, low land or
ditch. The effluents are usually characterized by low or high pH, high BOD and COD,
high turbidity, high color, high suspended solids etc. As a result, discharge of
untreated wastewater causes death of aquatic life and the resulting environmental
pollution effects on plants, animals and human. The study attempts to identify simple
and cost effective approaches to stabilize pharmaceutical waste.
Navana Pharmaceuticals Ltd. is one of the largest pharmaceutical industries of
Bangladesh which produces various types of products from different plants. Wastes
from different plants are discharged in a surface drain and then flow combinedly. This
study has been carried out for biological treatment of this liquid waste by aerated
lagoon process and Activated sludge process. For Aerated lagoon process BOD5,
COD, color, turbidity, EC and DO were taken as indicators for the assessment of
treatment efficiency; for activated sludge process BOD5, COD, turbidity, TSS and
TDS were taken as indicators. Chemical treatment was also carried out for color,
turbidity and COD removal. From chemical treatment process it was found that
chemical treatment was effective for color and turbidity removal but not so effective
for COD removal. 100 mg/l alum may reduce color by 50% and turbidity by 67%.
From aerated lagoon process, it was observed that treatment performance depends on
pH and pH of about 6.0 was effective for biological treatment by aerated lagoon.
Aeration with pH value 6.0 for four days can reduce COD by 88% and BOD5 by 96%.
And can also increase DO up to 5 mg/l. The rate constant was found as 5.6 d-1 at 30oC
temperature for four day aeration. COD can be reduced by 90% and BOD5 by 98% by
Activated Sludge process with detention time eight hours without physicochemical
treatment. Where the existing ETP which uses activated sludge process reduces COD
by 94.6%.
A comparison among existing ETP and different processes tried in this study was
carried out, focusing on the treatment efficiencies and area requirement. In this study
COD removal efficiency was found higher in existing ETP than coagulation process,
aerated lagoon process and activated sludge process tried in the laboratory due to
presence of a physicochemical treatment unit. Area requirement was higher for
aerated lagoon process but lower for activated sludge process. However, aerated
lagoon process is economical where land cost is insignificant.
