HeavyMetals and Organics
ReportNo WSAA 79
Thissurvey of heavy metals and organics in domestic sewage was carried out in theAdelaide metropolitan area in 1992-93 in order to determine the pollution loadrelative to that of Commerce and Industry. Surveys of four households and fourwet wells were undertaken.
Theresults indicate that the metals with significant loadings are copper,aluminium and zinc. At least half of the copper comes from the householdplumbing whilst a similar proportion of the aluminium is in the water supplyentering the households. Most of the zinc is from the bathroom. Boron loadingis significant and is a component of both bathroom and laundry wastewater.
Organicand TDS loadings in household discharges were generally proportional to thevolume of water used in each area, with more TDS (Total Dissolved Solids) andsuspended solids discharged from the laundry than from the bathroom. Althoughthe kitchen had high concentrations of organics, the low volume gave a loweroverall load. The overall organic load structure from household sampling wasincomplete, however, as the household samples did not include the toiletwastes, the wet wells consequently gave better data for comparison with the loadingson treatment works.
Phosphorusloadings from households were significant, exceeding the highest metal load byat least a factor of ten. The levels of phosphorus in some household laundrysamples were almost twice that recommended in the AWRC guidelines fordischarges to sewers. Even where there was a significant industrial input, thehousehold load was some 50 percent of the total.
Thephosphorus load pattern requires further clarification but it is the pollutantmost obviously a target for load reduction. Aluminium and copper loads are notdue to household activities but zinc and possibly boron loads might betargetted for reduction.
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