Investigation of solid waste leachate treatability by submerged membrane electro-bioreactor system

Membrane electro-bioreactor system (SMEBR) is a new system composed of biological process, membrane filtration process and electrokinetic process for the treatment of leachate from landfill. The main purpose of this thesis is to investigate this new technology which was carried out in three stages. In the first stage of work; an extensive characterization of leachate from the Sanitary Landfill "ISTAC" in Istanbul - Turkey has been carried ouAt the second stage, optimization studies were carried out to determine the appropriate currents and exposure time. For this purpose, different currents and exposure time was run in the activated sludge where the optimum current is determined as 2A (current density is 24 mA/cm2) and exposure time is 15 minutes. Activated sludge was provided from taken the aerobic tank of the leachate biological treatment plant at the ISTAC Odayeri Sanitary Landfill. As a result of the studies carried out at. In the last stage, the installation, operation and optimization of the reactors have been carried out. In order to investigate the effects of the electric current on the biological treatment, the studies were performed in parallel with the conventional submerged membrane bioreactor (SMBR) systemwas inoculated with the same activated sludge mentioned above. After the reactors reach the steady-state condition, aluminum electrodes with different perforated rates were placed in the SMEBR system. 24 mA/cm2 CD and the 15-minute exposure time divided by the steady-state 5-day hydraulic retention time (HRT). The SMEBR system was supplied with two different combinations. Period I; 3 minutes per day at a current density of 24 mA/cm2, Period II; 6 minutes per day at a current density of 24 mA/cm2. The SMEBR system was operated for 25 days in both periods for a total of 50 days. The performance of SMEBR system for leachate treatment was evaluated by comparing the performance of the two periods with each other and with the SMBR system, following parameters such as temperature, pH, conductivity, dissolved oxygen (DO), color, chemical oxygen demand (COD), total organic carbon (TOC), ammonia nitrogen (NH3-N), total nitrogen (TN). The electric current applied in Periods I and II didn't show any negative effect on the bacterial life. In addition, system efficiency was evaluated based on pollutants removal parameters in the effluent water such as the changes in the activated sludge characteristics (EPS, SMP, CST, Particle Size, Zeta Potential) and the membrane flux results. The general trend of the pollutantsremoval parameters efficiency was variable during all the 50 days of study. However, SMEBR was found to be more effective than the conventional SMBR treatment especially with the application of Period II conditions. EPS analysis in sludge showed that electrical current expose bacteria to stress and induce a slight increase in EPS value resulting in membrane fouling in comparison to the conventional system. Compared with conventional SMBR, membrane fouling occurred in SMEBR later. There was no significant difference between SMEBR and SMBR regarding EPS results. However, according to the SMBR, the SMPP value was lower in SMEBR. During the electric current, the sludge filterability in the SMEBR was increased and zeta potential values varied from -50 mV to -10 mV in close proximity to each other in the two systems. The chemical properties of surfaces of the SMEBR and SMBR membranes were characterized by FTIR spectroscopy. The FTIR of both systems showed similar FTIR spectra. Passivation or precipitation occurred on the electrodes during operation. The SMEBR dissolved Al electrode was used to assess the daily accumulation in waste sludge. In addition, a cost analysis was carried out for the treatment of leachate with SMEBR. In Period II, SMEBR system COD removal efficiency was higher than SMBR for for about 4000 mg/L which is equal to a total cost of 0,175 €/m3. SMEBR effluent quality was evaluated based on the discharge standards in ISKI and SKKY. All parameters except COD were found to be in accordance with the discharge standards noting that study results were considerably lower than these values. The evaluation of the xperimental work shows that the new system SMEBR is able to treat leachate from landfill.