Question

Indicate risk or environmental concern associated with the following parameters when receiving on water sink, if it was not treated.

BOD, COD, TPH, PAH, TKN, Sulfate, Phenols, PCBs

Answer 1

BOD ( Biological Oxygen Demand ) - Discharge containing higher BOD to water, can take the dissolved oxygen content of water source, to threshold level or zero. This will kill all the aquatic animals, as water is now void of dissolved oxygen.

COD ( Chemical Oxygen Demand ) - Discharge containing higher COD to water, have the same effect as that of BOD. It can take the dissolved oxygen content of water source, to threshold level or zero, which will kill all the aquatic animals, as water is now void of dissolved oxygen.

TPH (Total Petroleum Hydrocarbon) - The TPH is a environmental concern subjected to proper analysis of individual petroleum components (fuel oil, gasoline, naphtha, benzene etc ) . If higher TPH contaminated water is used as a drinking source, then it is also a concern on human health. The contents of TPH is very important to decide the effect on human health. For eg: If TPH analysis of ground water confirms the presence of benzene, then it is unsafe to drink, as benzene is known to be highly carcinogenic (cancer causing compound).

PAH (Polynuclear Aromatic Hydrocarbon) - PAH in water is a risk. It is known to affect human health and major compounds within PAH group (like FluoroAnthene-FA) are known to cause cancer if consumed by humans.

TKN (Total Kjeldahl Nitrogen) - Higher TKN is a environment concern and not a risk as presence of nitrogen increases the multiplication of biological organism, algae etc with potential for odour. This may also render the water unsuitable for drinking.

Sulfate - Low sulfate level do not pose any risk to humans. However at high sulfate levels , a risk of potential diarrhoea exists if consumed.   

Phenols - Phenol compound is highly toxic to humans (not carcinogenic) and can be fatal above certain concentration. Phenol is irritating to the skin & eyes under acute or short term exposures to humans. Phenol is considered to be quite toxic to humans on chronic (long-term) exposure. Chronic exposure may cause weight loss, diarrhea, etc.

PCB (Poly Chlorinated Biphenyl) - PCB's are likely to be carcinogenic (cancer causing) in nature and hence toxic to humans and aquatic life.