Describe the key contaminants in sewage which wastewater treatment targets, and their likely concentrations. Use journal articles and text books to assist

The contaminants in sewage varies depending on the source of the sewage. There are organic component and inorganic components such as: metal and solids components. Industrial and household waste have a large contribution in the content of sewage that are targeted by wastewater treatments. There are various wastewater treatment technologies available depending on the chemical properties of the contaminant. Composting is one the main treatment technology available for organic waste that contain harmful chemicals like linear alkylbenzensulphonates (LAS) that are highly toxic and are also endrocrine disruptors and pharmaceutically active chemical. The table below contains main contaminants in a typical sewage system, their likely concentration and possible treatment.

Contaminants Likely concentration (average)

Possible Treatment process

Anions(Graczyk, Chalew et al. 2009)

85 mg/l -190 mg/l Chemical treatment

Cations 60 mg/l -110 mg/l Chemical treatmentOther Al, B, Mn, SiO2 2 mg/l -12 mg/l SedimentationTotal dissolved solids 150v-380 mg/l MembranesDissolved organic carbon 22.1mg/l-56.2 mg/l Composting,

Total Carbon on Demand 204 mg/l -440 mg/l Carbon adsorptionSoluble COD 108 mg/l -372 mg/l Air StrippingDissolved organic carbon(Huang, Li et al. 2010)

22.1 mg/l -56.2 mg/l Air stripping

Nutrients such as Nitrogen and Phosphorus

50 mg/l -70 mg/l Chemical treatment, ion exchange

The composition depicted in Table 1 is for domestic wastewater obtained from Graczyk, Chalew et al. (2009) and Huang, Li et al. (2010). Industrial waste water, compared with domestic will have different composition. In addition to the chemicals listed below, there are other emerging chemicals in the wastewater. These chemicals have only been identified recently and their toxicity is unknown.(Graczyk, Chalew et al. 2009). These chemicals could be a result of an increase in industrial and pharmaceutical applications.

Graczyk, T. K., T. E. Chalew, Y. Maschinski and F. E. Lucy (2009). Wastewater Treatment (not infectious hazards). Encyclopedia of Microbiology (Third Edition). M. Schaechter. Oxford, Academic Press: 562-568.Huang, M.-h., Y.-m. Li and G.-w. Gu (2010). "Chemical composition of organic matters in domestic wastewater." Desalination 262(1–3): 36-42.