Integration of ultrafiltration membrane process with chemical coagulation for proficient treatment of old industrial landfill leachate

• Coagulation integrated UF process for the treatment of landfill leachate. • Process showing higher reduction for color, odor, and turbidity. • Study on the performance efficacy of various chemical coagulants. • Cost estimation for integration process. • Kinetic of the supernatant liquid was studied using SMOLUCHOWSKI equation. Old industrial landfill leachate (OILL) poses a significant challenge to the environment, due to the large volumes of the solid waste directly discharged into landfills which leach out by percolation during rainfall and degradation of organic waste. Various separation processes have been used for the treatment of OILL to reduce environmental pollution. The innovation in the present study is the integration of membrane ultrafiltration (UF) process with chemical coagulation to remove pollutants such as total dissolved solids (TDS), conductivity, turbidity, and color from an OILL. Various coagulants such as ferric chloride (FeCl 3 ), activated carbon (AC) and their combinations with alum ((Al(SO 4 ) 3 ) and lime (Ca(OH) 2 ) were used to optimize pretreatment by coagulation. Experiments were conducted by varying the composition of coagulants and sedimentation time. Reduction in parametric values of TDS from 3200 to 1500 mg L -1 , conductivity from 5.00 to 2.34 mS cm −1 , turbidity from 226 to 1 FAU, color from 2930 to 10Pt-Co, and pH from 8.23 to 4.86 were achieved by a combination of coagulation by FeCl 3 and UF membrane process. Moreover, greater removal of turbidity and color of 98.7% and 99.48%, respectively were observed. Further, the coagulation kinetics were established on the basis of the pH of the supernatant liquid through modeling using SMOLUCHOWSKI equation and observed to follow first-order kinetics. FeCl 3 coagulant + UF was found capable of promoting maximum removal of color and turbidity compared to the other combinations. The integrated process exhibits advantages of small footprint of equipment used, economy, environmental safety, low energy consumption, and ease of scale-up for OILL treatment with simultaneous water reclamation of at least 70%.