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Table 3 Summary of some studies conducted for biological removal of PAEs

From: A comparative study of anaerobic fixed film baffled reactor and up-flow anaerobic fixed film fixed bed reactor for biological removal of diethyl phthalate from wastewater: a performance, kinetic, biogas, and metabolic pathway study

Treatment method Substrate type (PAEs) Experimental conditions and removal efficiency Important observation Refs.
Anaerobic/anoxic/oxic (AAO) treatment system DMP The optimal HRT and SRT for DMP and nutrients removal were 18 h and 15 days, respectively, and the degradation rates of anaerobic, anoxic and aerobic zones for DMP were 13.4, 13.0, and 67.7%, respectively The biodegradation process of DMP by the selected method was in accordance with the first-order kinetics model. Under the optimal conditions, about 73.8, 5.8, 19.3, and 1.1% of DMP was biodegraded, released in the effluent, accumulated in the system, and remained in the waste sludge, respectively [60]
Trickling filter DEP and DEHP Trickling filter achieved 94–99% of DEP and 44% of DEHP removal DEHP was the most recalcitrant among the selected phthalates and DEP with less molecular weight was biodegraded with higher rate [61]
Cyclic activated sludge technology (CAST), anoxic/oxic (AO), and anaerobic/anoxic/oxic (AAO) processes DEP, DMP, DnBP, BBP, DEHP and DOP The overall removal efficiency of all the selected PAEs was more than 72% in CAST while AO and AAO only achieved about 30% of PAEs removal The better performance of the CAST process was attributed to its better indoor-conditions for bacterial community [62]
Moving bed biofilm reactor (MBBR) DAP and DEP In optimum conditions with HRT of 9 h, about 95 and 94% of DEP and DAP were removed, respectively. In addition, more than 92% of COD removal was achieved for both phthalates MBBR tolerated both of the selected phthalates with the influent concentrations of 100–300 mg L−1. Sludge yield constants (Y) varied from 0.3 to 0.54. The maximum specific growth rates were 0.37 and 0.34 day−1 for DEP and DAP, respectively [8]
Up-flow anaerobic sludge blanket reactor (UASB) DMP More than 99% of DMP and 93% of COD were removed from the wastewater containing 600 mg L−1 of DMP (corresponding to 3 g COD L−1 day−1) of organic loading rate of) at 8 h of HRT The sludge yield was estimated as 0.08 g VSS g COD−1. DMP was first de-esterified to mono-methyl phthalate (MMP) and, then, to phthalate (or phthalic acid) and, subsequently de-aromatized and converted into methane and CO2. The maximum specific degradation rates of DMP, MMP, and phthalate were 415, 88, and 36 mg (g VSS day)−1, respectively [63]
Anaerobic/anoxic/oxic treatment system (AAO) DnBP The optimal HRT and SRT for DnBP removal were 18 h and 15 days, respectively. In the mentioned conditions, about 72.66% of DnBP was degraded by the selected process, 24.44% was accumulated in the system, 2.44% was released in the effluent, and 0.5% remained in the waste sludge Increasing SRT from 10 to 15–25 days resulted in increasing removal efficiency from 90 to 95%. Higher SRT improved DnBP biodegradation efficiency. The removal efficiencies of anaerobic, anoxic and oxic reactors were 17.14, 15.02, and 63.46% of the total DnBP removal, respectively [64]
Submerged membrane bioreactor (aerobic condition) DEHP The removal efficiency of DEHP under HRTs of 4 and 6 h, SRT of 140 days, and sludge concentration of 11.5 and 15.8 g VS L−1 ranged between 91 and 98% The removal of DEHP was closely dependent on the membrane pore size and about 74% of inlet DEHP was biodegraded [65]
  1. DMP dimethyl phthalate, DEHP bis(2-ethylhexyl) phthalate, DnBP di-n-butyl phthalate, BBP butyl benzyl phthalate, DOP di-n-octyl phthalate, DAP diallyl phthalate