Filtration Cathode Bioelectrochemical Systems For Advanced Wastewater Treatment And Desalination

Bioelectrochemical system(BES),as a device which can treatment wastewater and at the same time produce electricity from the oxidiation of organic matter contained in wastewater,is a newly developed technology for wastewater treatment and energy recovery.However,traditional BES has some shortages,such as insufficient organics removal,limited energy production,etc.In this thesis,to enhance the wastewater purification performance,a conductive filtration membrane was fabricated and combined with BES as its filtration air cathode;to utilize the“low grade” energy produced in BES,a resin packed microbial desalination cell(MDC)was built to in-situ utilize the energy for water desalination.By combining these two technologies,a modularized filtration cathode MDC was invented and fabricated for simultaneous advanced wastewater treatment and self-driven desalination.Homogeneous conductive carbon membrane and nitrogen doped carbon nanotube(N-CNT)membrane were fabricated.They both have small pore size(<0.6?m),high porosity(>43.4%),and high specific surface area(>32.2 m2/g).They were assembled in BES as filtration cathodes and operated with wastewater flowing from anode to the filtration cathodes.Results showed that filtration cathode BES exhibited higher power generation and organics removl performance than traditional BES.The cathode mass transfer and inter-electrode ion migration could be enhanced by increasing filtration flow rate.The power generation of BES could be improved by increasing cathode surface area and thickness.In addition,operation at high current could mitigate fouling formation on the filtration cathode.Proposed ion-exhange resin packed MDC achieved higher desalination rate and lower ohmic resistance compared to traditional MDC,and multi-ions contained in salty water could be effectively removed.A stacked resin-packed MDC with 10 L was further fabrited to desalinate synthesized secondary wastewater.The desalination efficiency realized 96.3% with only 4.2% production of concentrate.The final conductivity of diluate was only 42 ?S/cm,which was comparable with the effluent quality of first stage reverse osmosis.The volume production of diluate was96%,and that of concentrate was only 4%.By combining these two technologies,a modularized filtration cathode MDC was invented and built using N-CNT membrane as filtration cathode.With wastewater successively flowing from anode to the filtration cathode and finally to the middle desalination stack,the filtration cathode MDC realized a diluate volume production of 82.2%,with COD removal efficiency of 97.2% and desalination efficiency of 98.7%.The concentrate volume production was 17.8%,and it recovered almost all the salt and phosphorous,and 74.1% of nitrogen,which can be further concentrated for production of valuable chemicals.This filtration cathode MDC was a successful combination of filtration technology with BES,realizing simultaneous advanced wastewater treatment and self-driven desalination.