Page 249 - Materials Chemistry, Second Edition

230 Life Cycle Assessment of Wastewater Treatment

Steps required for analysis of heavy metals

Representative sampling

To prevent analyte loss
e.g. sorption on vessel wall

Contamination form the environment, wares,
chemicals added to the sample

Transfer the sample to the lab

Treatment of sample prior to analysis

Choose of the method considering its limitations

Calibration of the vessels, instrument

Preparation of sample, all solutions, standards correctly

To test the accuracy of the method using certi ed
reference materials (CRM)

Evaluation of results statistically

FIGURE 11.3 Steps needed to analyze the heavy metals in wastewater.
Heavy metal removal from inorganic profluent can be accomplished by ordinary
treatment forms. The removal of heavy metals from industrial wastewaters can be
accomplished through different treatment choices, including such unit operations
as compound chemical precipitation, coagulation, complexation, activated carbon
adsorption, ion exchange, solvent extraction, electro-winning, cementation, and
membrane operations. Figure 11.5 demonstrates treatment methodologies for the
removal of heavy metals. The advantages and disadvantages of different treatment
methodologies for heavy metal removal from groundwater are listed in Table 11.2.

11.5.1 cHeMical precipiTaTion
Chemical precipitation stands out among the most widely used methods for heavy
metal removal from inorganic emissions in industry because of its straightforward
operation. The conventional forms of chemical precipitation deliver insoluble forms