Development of functionalized polymeric membranes for the recovery of value-added products and treatment of industrial / domestic wastewater
Creators: name: SHAIK, Nazia
Publisher: name: RMIT University
Year: 2024
Subjects: classificationCode: 400410
subject: Wastewater treatment processes
classificationCode: 400411
subject: Water treatment processes

description: Water is an essential resource for the survival of living organisms in the ecosystem. Nowadays, the world is facing problems due to the shortage of water from various resources. Water discharged from industrial, domestic, and agricultural sources can be recycled for reuse. With water demand increasing day-by-day, scientists are required to find sustainable solutions. Thus, the recovery of water from industrial wastewater (IWW) and domestic wastewater (DWW) is a feasible, cost-effective, and substantially positive benefit for the environment. Membrane technologies play a pivotal role in treating IWW and DWW due to their low energy consumption. In this thesis, membrane-based technologies have been applied widely for the treatment of real IWW/DWW, either individually or in combination with other processes, to reach reusable water quality standards. These processes have also been extensively used for the recovery of value-added products from food sources. Hence, the treatment of existing  IWW/DWW has been discussed briefly in the following sections.

Membrane-based hybrid processes have been used to treat food processing effluents such as kitchen and rice gruel wastewater to recover water, as well as an aqueous solution for isolation of value-added stevia leaves. For water reclamation, effective removal of chemical oxygen demand (COD) and electricity generation was investigated using a microbial fuel cell (MFC), which is an eco-friendly energy source. Hence, an ionically crosslinked nanocomposite membrane, based on aniline-treated polysulfone (APSf) doped with sulfonated multiwalled carbon nanotube (SMWCNT) was prepared to facilitate proton conduction. The APSf/SMWCNT membrane containing 1% by weight of carbon nanotubes provided a maximum power density of 304.2 mW/m2 with substantially high columbic efficiency (17%) and considerable removal of COD (82%) as compared to Nafion 117 or APSf incorporated nanotubes (0.5%).  Domestic rice gruel wastewater (RGW) was treated by methanol coagulation integrated aerobic membrane bioreactor (AMBR) incorporated with a spiral wound hydrophilized ultrafiltration (HF-UF) membrane module of 5 kDa MWCO at its available temperature of 80 °C and also after the feed was cooled down to room temperature (30 ± 2 °C), for the reduction of turbidity, total dissolved solids (TDS), conductivity and COD. Other coagulants such as ethanol and HCl were also tried. A comparison study was carried out using various coagulants such as methanol, ethanol, and hydrochloric acid for integration with HF-UF membrane to determine overall process efficiency at 30 °C. Methanol coagulation + HF-UF membrane based integrated process was able to achieve removal of total dissolved solids (TDS) of 94 %, turbidity 95 %, conductivity and COD of 91 % and 79 %, respectively. The overall process was economically feasible and eco-friendly. Stevia is 300 times sweetener than sucrose, and used as a substituent by diabetic patients to control blood sugar levels. Stevia leaves are dewaxed by hexane at 60oC and then the sweetener is extracted along with several impurities by water at 120oC. The solution is then passed through membranes such as microfiltration (MF) and ultrafiltration (UF) to remove impurities before concentration of stevia by nanofiltration (NF).
 
The next chapter discusses processing of the environmentally hazardous old industrial landfill leachate (OILL). A coagulation/ultrafiltration hybrid process has been used to reduce impurities such as turbidity, color, and TDS from the wastewater. Various coagulants such as alum (Al(SO4)3), lime (Ca(OH)2), ferric chloride (FeCl3), and activated carbon (AC) were used individually and in combination. Experiments were conducted by varying the composition of coagulants, stirring speed, and sedimentation time. Reduction in parametric values of TDS from 3200 to 1500 mg/L, conductivity from 5.00 to 2.34 mS/ cm, turbidity from 226 to 1 FAU, color from 2930 to 10 Pt-Co, and pH from 8.23 to 4.86 were achieved by a combination of coagulation by FeCl3 and UF membrane process. Moreover, greater removal of turbidity and color of 98.7 % and 99.48 %, respectively, were observed. The efficiency in reduction of turbidity and color was found virtually by simulation and modelling to validate experimental data.

The last chapter deals with the treatment of effluents from steel and aluminium manufacturing industries. The reduction in the chloride ion concentration from coke oven wastewater in the steel industry from 2000 ppm to &lt; 500 ppm is crucial for its recycle. Polyvinylpyrrolidone (PVP) coated polyamide (PA) nanofiltration (NF) membrane was used for recovery of more than 80% of water from the corrosive effluent with 75% chloride rejection. The effects of feed pressure on permeate flux, chloride rejection and water recovery has been studied to optimize the NF process. The reduction in parameters such as TDS, conductivity, turbidity, hardness, and chloride concentration in the permeate samples was evaluated. The experimental results of NF were compared with that of electrodialysis and reverse osmosis processes for chloride removal from a synthetic feed. The process was scaled-up to an industrial scale of 5 M3/h at TATA Steel, Haldia wherein the NF plant is running successfully since three years. (SA). A highly alkaline wastewater containing sodium aluminate along with high TDS, COD and conductivity was collected from National Aluminium Company Limited (NALCO), Orissa, India. Pre-treatment followed by reverse osmosis using flat sheet polyurea membrane worked well. During pretreatment by hydrochloric acid (HCl), the pH was decreased from 12.5 to 7.1. The experiments were conducted by varying the feed composition of the  wastewater. The maximum water recovery and flux were found to be 74 % and 73.9 L/m2h.