Application of Advance Oxidation Processes to Achieve Zero Liquid Discharge in Pharmaceutical Industry

Abstract

 Water is a scarce resource and essential for all the industries and human being. Due to anthropogenic
activities, pollution problems of water are being critical today. To overcome water pollution problem, environmental
regulatory requirements are becoming more stringent and enforcing water intensive industries like pharmaceutical
industries to reuse of its treated effluent for various purposes which can be possible by adopting zero liquid discharge
(ZLD) system in industries to minimizing water consumption. Pharmaceutical industries are generating highly colored,
toxic and hazardous wastewater containing recalcitrant organic compounds which are highly hazardous, toxic, chemical
stable and low biodegradable in nature which are not treatable by conventional treatment methods and pose serious
human health and ecological risks. To achieve the zero liquid discharge in pharmaceutical industries, one of the most
challenging issues is the removal of recalcitrant compounds in pharmaceutical wastewater. Therefore, treatment of
pharmaceutical wastewater by using various advance oxidation processes (AOPs)are potential alternative solution to
remove recalcitrant organic compounds, reduce chemical oxygen demand (COD) and improve biodegradability index of
pharmaceutical wastewater which advantages to achieve zero liquid discharge in pharmaceutical industries. The
objective of present study was to assess the possibility of UV, H2O2, UV/H2O2 and Fenton process in a laboratory-scale
setup for the pretreatment of pharmaceutical wastewater and to determine the influences of various parameters on the
pretreatment of pharmaceutical wastewater. The experimental results show UV, H2O2 and UV/H2O2 are not effective for
the treatment of pharmaceutical wastewater except Fenton process. In the present study, the optimum conditions had
been determined for Fenton process, and it was found that % COD removal efficiency obtained after 120 min of reaction,
was about 68.2%. The optimal parameters were: initial pH=3; [H2O2] =600 mg/L; [Fe2+] =200 mg/L and for 8640 mg/L
initial COD of pharmaceutical wastewater. The results showed that COD removal efficiency first increased then
decreased with the increase of solution pH, and the highest COD removal appeared as pH was about 3.0. The COD
removal rose from 36.4 % to 68.2 % with H2O2 concentration from 50 mg/L to 1100 mg/L and from 4.1 % to 63.1 % with
Fe+2 concentration from 25 mg/L to 250 mg/L. The COD removal first increased then decreased with the mole ratio of
Fe+2
to H2O2. The maximum COD removal appeared as the mole ratio of Fe to H2O2 is 1:5. The COD removal increased
with time and leveled off after 120 minutes. At optimum condition, improvement in biodegradability index was takes
place from 0.95 to 0.27, which shows that the Fenton process is very suitable for the treatment of pharmaceutical
wastewaters. After combination of Fenton process with conventional methods, it can possible to reuse the treated
wastewater in the industry for various purpose or safely discharge into different streams or transfer into a sewage
treatment by means of advanced oxidation processes