A comparative study of occurrence and fate of endocrine disruptors: diethyl phthalate and dibutyl phthalate in ASP- and SBR-based wastewater treatment plants.

Phthalates are endocrine-disrupting chemicals which affect endocrine system by bio-accumulation in aquatic organisms and produce adverse health effects in aquatic organisms as well as human beings, when come in contact. Present study focuses on occurrence and removal of two phthalates: diethylphthalate (DEP) and dibutylphthalate (DBP) in two full-scale wastewater treatment plants (WWTPs) i.e. sewage treatment plants (STPs) based on well-adopted technologies, activated sludge process (ASP) and sequencing batch reactor (SBR).Gas chromatography-mass spectrometry (GC-MS) analysis was performed for both wastewater and sludge sample for determination and identification of the concentration of these compounds in both STPs by monitoring the STPs for 9 months. It was observed that the concentration of DEP was less than DBP in the influent of ASP and SBR. Average concentrations of DEP and DBP in sludge sample of ASP were found to be 2.15 and 2.08 ng/g, whereas in SBR plant, these values were observed as 1.71 and 2.01 ng/g, respectively. Concerning the removal efficiency of DEP, SBR and ASP plants were found effective with removal efficiency of 91.51 and 91.03 %, respectively. However, in the case of DBP, SBR showed lower removal efficiency (85.42 %) as compared to ASP (92.67 %). Comparative study of both plants proposed that in ASP plant, DBP reduction was higher than the SBR. Fourier transformation infrared (FTIR) analysis also confirmed the same result of sludge analysis for both STPs. Sludge disposal studied with scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and thermo-gravimetric analysis (TGA) techniques confirmed that sludge of both STPs have high calorific value and can be used as fuel to make fuel-briquettes and bottom ash to make firebricks.

Occurrence and fate of endocrine disrupting chemicals in ASP based sewage treatment plant in Hardwar.

The occurrence of emerging contaminants such as endocrine disrupting chemicals (EDCs) in our water resources is of prime concern. With this context, fate and seasonal variation of six EDCs (testosterone, T; progesterone, P; diethyl phthalate, DEP; dibutyl phthalate, DBP; propyl-paraben, PP and butyl-paraben, BP) were assessed throughout the year, i.e. in rainy, winter, spring and summer seasons in the raw, treated wastewater and activated sludge in an activated sludge process (ASP) based sewage treatment plant (STP) located in Haridwar, India. Qualitative and quantitative measurements were performed by gas chromatography-mass spectrometry (GC-MS) analysis. Results indicate that in summer, the examined STP could effectively remove 82.9% of T, 86.4% of P, 95.5% of DEP, 92.4% of DBP, 91.5% of PP, and 89.9% of BP from the wastewater. Among the EDCs considered, higher removal efficiencies were achieved for phthalates in the summer season. GC-MS analysis showed that a small fraction of EDCs was sorbed on the solid fraction of activated sludge. Scanning electron microscopy, energy dispersive X-ray spectroscopy and Fourier transformation infrared spectroscopy analysis were also performed to investigate the occurrence of EDCs in biomass samples. Results of this study also demonstrated that removal efficiency, assessed in terms of physicochemical and microbiological parameters, was maximum in summer and reached minimum in rainy season.