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198 Chapter Six

Table 6.1 Potential sources of groundwater pollution arising from domestic, industrial and agricultural activities. Adapted from
Jackson (1980).
Contaminant source Contaminant characteristics
Septic tanks Suspended solids 100–300 mg L −1
BOD 50–400 mg L −1
Ammonia 20–40 mg L −1
Chloride 100–200 mg L −1
High faecal coliforms and streptococci
Trace organisms, greases
Storm water drains Suspended solids ~ 1000 mg L −1
Hydrocarbons from roads, service areas
Chlorides or urea from de-icing
Compounds from accidental spillages
Bacterial contamination
Industry
Food and drink manufacturing High BOD. High suspended solids. Colloidal and dissolved organic substances. Odours
Textile and clothing High suspended solids and BOD. Alkaline effluent
Tanneries High BOD, total solids, hardness, chlorides, sulphides, chromium
Chemicals
Acids Low pH
Detergents High BOD
Pesticides High TOC, toxic benzene derivatives, low pH
Synthetic resins and fibres High BOD
Petroleum and petrochemical
Refining High BOD, chloride, phenols, sulphur compounds
Process High BOD, suspended solids, chloride, variable pH
Plating and metal finishing Low pH. High content of toxic metals
Engineering works High suspended solids, hydrocarbons, trace heavy metals. Variable BOD, pH
Power generation Pulverized fuel ash: sulphate, and may contain germanium and selenium. Fly ash and flue
gas scrubber sludges: low pH, disseminated heavy metals
Deep well injection Concentrated liquid wastes, often toxic brines. Acid and alkaline wastes. Organic wastes
Leakage from storage tanks and pipelines Aqueous solutions, hydrocarbons, petrochemicals, sewage
Agriculture
Arable crops Nitrate, ammonia, sulphate, chloride and phosphates from fertilizers. Bacterial
contamination from organic fertilizers. Organochlorine compounds from pesticides
Livestock Suspended solids, BOD, nitrogen. High faecal coliforms and streptococci
4
Silage High suspended solids, BOD 1–6 × 10 mg L −1
Carbohydrates, phenols
Mining
Coal mine drainage High TDS (total dissolved solids), suspended solids. Iron. Low pH. Possibly high chloride
Metals High suspended solids. Possibly low pH. High sulphates. Dissolved and particulate metals
Household wastes High sulphate, chloride, ammonia, BOD, TOC and suspended solids from fresh wastes.
Bacterial contamination. On decomposition: initially TOC of mainly volatile fatty acids
(acetic, butyric, propionic acids), subsequently changing to high molecular weight
organics (humic substances, carbohydrates)
+
BOD, biological oxygen demand; TOC, total organic carbon; pH, −log (H ).
10

the scientific information with which decisions on political, legal and socioeconomic issues, policy
water quality can be based, for example toxicity data, makers are able to set water quality objectives for the
information relating to the available water treat- attainment of good quality.
ment technology and environmental degradation For groundwater, the setting of chemical quality
rates. With this information, and taking into account objectives may not always be the best approach since