Multivariate analysis of heavy metals in pharmaceutical wastewaters of National Industrial Zone, Rawat, Pakistan

Water is the basic necessity of life, and its quality affects biological processes. Anthropogenic activities increase concentration of harmful pollutants like heavy metals in the environment. The current study is the first attempt for the assessment of heavy metals in the wastewaters released from pharmaceutical industries of the National Industrial Zone, Rawat, Pakistan. The metal concentrations depicted the following trend: Fe » Zn > Ni > Pb > Mn > Cr 6+  > Cd > Cu. Mn, Cu and Zn were recorded within the maximum permissible limits of Pakistan National Environmental Quality Standards (Pak-NEQS) and World Health Organization (WHO) in all the pharmaceutical wastewater samples; but Cd, Pb, Fe, Cr 6+ and Ni surpassed one or both the admissible limits which can be the potential threat to the underground water resources, aquatic life and human health. The highest concentration was detected for Fe (10.86 ± 0.01 mg.L −1 ) in the wastewater sample of MB-12, which was much higher than the maximum NEQS limit of 2 mg.L −1. Maximum significant correlations were observed for Cr with various water quality parameters, including dissolved oxygen, phosphates, salinity and Cu during Pearson's correlation analysis. Multivariate techniques including cluster analysis and principal factor analysis were used to extract the latent information from the data set to assess the water quality. Three principal factors were extracted during factor analysis containing high positive factor loadings of Cd, Fe; Cu, Mn; and Pb in the principal factors 1, 2 and 3 respectively, indicating the contribution of the anthropogenic and industrial operations in the water contamination due to the discharge of improperly treated or untreated pharmaceutical wastewater. Cluster analysis based dendrogram resulted in the formation of single cluster containing reverse osmosis treated wastewater samples along with the untreated wastewaters which strongly recommends the need to adopt wastewater treatment methods with efficient processes for proper discharge of their pharmaceutical effluents into fresh waters, thus reducing the potential ecological hazards.