Study Of EGSB-MBR-Ozone Processes For Bamboo Wastewater Treatment

With the transformation of bamboo material from production and living timber to indursty timber, most recently, bamboo production processing factory have been developing rapidly. Althought it brought great vitality to the local economy, the tons of wastewater produced from bamboo industry made a huge chanllenge to the surrounding environment. Therefore, the treatment of bamboo industry wastewater (BIWW) should be accomplished with urgency.Based on the properties of BIWW and the treatment processes for wastewater of the same type as well as anaerobic static tests, EGSB-MBR-Ozone proceses had been designed to treat BIWW. The feasibility of anaerobic biodegradation BIWW and inhibition effects of Cu (Ⅱ) as well as their kinetic paramters were investigated, the effects of parameters on EGSB, MBR and Ozone processes treatment efficiency and it's optimizing were also studied, the sludge in EGSB rector was scanned by a environment scanning electron microscopic (ESEM), finally the main pollutants and it's molecular distribution of wastewater before and after ozone oxidation were researched. The results were concluded as follow:1. Study on the inhibitory effects of Cu (Ⅱ) on fermentative methane production using bamboo wastewater as substrat. Typical BIWW was chosen to conduct the anaerobic static tests, methane produced from each system was collected by Smith fermentation tube, and then the cumulative methane production curves were fitted by using Gompertz equation. The results showed that the anaerobic treatment of the BIWW was quite feasible; the adaptation time required for the anaerobic microorganisms increased with the increasing COD in wastewater. The optimum COD concentration for methane production was 22780 mg L-1, with a maximum Rm (maximum CH4 production rate) value of 2.8 mL h-1, corresponding to a specific methanogenic activity (SMA) of 2.38mLCH4 (gVSS)-1 h-1.Low concentrations (5 mg L-1) of Cu (Ⅱ) showed a stimulating effect on methanogenesis, which was confirmed by Gompertz equation. When the concentration of Cu (Ⅱ) was below 200 mg L-1, the ability of methane-producing sludge would recover after certain period of adaption; while the Cu (Ⅱ) concentration above that value, inhibition effects appered throught the experimental time. However, methanogenic activity was completely blocked at the Cu (Ⅱ) concentration of 300 mg L-1, and the IC50 value for Cu (Ⅱ) was 183 mg L-1 (156 mg Cu (Ⅱ) gVSS-1).2. Study on the efficiency of EGSB reactor treating BIWW. After the research of the start up of EGSB reactor, the effectes of influent pH and organic loading rate (OLR) were investigated, and the sludge inside the reactor was scanned. The results showed that controlled the inflent pH in the range of 7.0-7.2, and increasing the OLR from 0.48 to 5.0 kg COD m-3 d-1 by way of increasing both quatity and COD concentration of infulent, the rector can be strated up successfully within 40 days with a constant 90% COD removal efficiency and stable effluent pH,VFA,TA and VFA TA-1.The OLR showed a greater impact, campred with pH, on EGSB reactor treating efficiency. The optimal influent pH and OLR were in the range of 4.5-5.5 and 3.5-5.5 kg COD m-3 d-1, respectively. The EGSB reactor showed a stable running with the constant COD removal efficiency of 85%-90% and stable giogas production as well as other normal efflent index.The sludge from the reactor showed a spherical appearance with smooth surface and briht black color. The ESEM image revealed that the density of bacteria increased significantly after the experiment, the occobacteria contained in the seeded sludge disappeared and the dominant bacter after the inoculation was bacillus.3. Study on the MBR reactor treating anaerobic effluent, and the effectes of hydraulic retention time (HRT) on organics removal efficiency and membrane fouling. The results showed that controlled the influent COD concentration in the range of 2 000-2500 mg L-1 and the pump-to-stop ratio was 3 min:1 min, when the HRT was 24h, the MBR reactor showed the highest average COD reduction which was 75% and the transmembrane pressure (TMP) was in the range of 1.5-2.0 kPa. While decreased the HRT to 18 h, the TMP was incrased to 3.5 kPa rapidly which is beyond our safety value 3 kPa. Even though the membrane cleaned manual to run again, the TMP still surpass the safety value rapidly, which means a serious membrane fouling problem appeared.4. Study on the ozone as an advanced oxidant for the treatment of BIWW. The effects of ozone inlet and initial COD concentration of wastewater on ozone oxidation were researched, and the main pollutants and it's molecular distribution of wastewater before and after ozone oxidation were also investigated. The results showed that ozonation was very effective in decolorizing and reducing organic compounds in the BIWW. At the gas flow rate of 60 L h-1 (3.15 g h-1), the color, chemical oxygen demand (COD) and total organic carbon (TOC) removal efficiency can achieved 95%, 56% and 39.9%, respectively. The gel permeation chromatography (GPC) chromatogram revealed that ozonation resulted in breaking of high molecular weight compounds in raw wastewater into lower molecular weight components instead of complete mineralization of the compounds. The majority of these compounds were identified both in raw and ozonated samples through GC-MS. In addition to ester derivatives (the main intermediates of ozonation),1-Chloroctadecane, Methyl stearate, Benzophenone and Alpha-Cyperone were identified as the by-products of ozonation during the advanced treatment of bamboo industry effluent. Nitrile compounds could not be detected after ozonation.5. The EGSB-MBR-Ozone processs can achieve a COD reduction of BIWW in the range of reduce 97-99% with a constant effluent COD in the range of 200-750 mg L-1 Assume that the amount and COD concentration of influent were 300 t and 20 000 mg L-1, respectively, the annual COD reduction for this processes would be 1.98×106kg.