Study On The Advanced Electrolysis Treatment Process Of Incineration Plant Leachates

Burning can greatly decrease the volume and quantity of solid waste, thereby reducing the handling capacity. As landfill’s loading increasing, the garbage incineration is becoming an important way of city garbage disposal. In order to reduce the burden of subsequent disposal, before the garbage incineration, it must firstly be stacked and extracted large mount of garbage leachate using the drainage system. And the garbage leachate contains a high concentration of organic substance(COD, BOD) and high ammonia(NH3-N), volatile fatty acid(VFA), heavy metals and other toxic pollutants. As a result, the garbage leachate treatment becomes an important environment topic.The garbage leachate using by experiment is coming from Chongqing Tongxing Fen Shao Chang, due to be piled up a relatively short time, the leachate has well biological activity. The factory uses " UASB + facultative anaerobic + aerobic + ultrafiltration + reverse osmosis" to deal with the leachate. This process can effectively remove the most of the organic pollutants in the leachate. As the pollutants in the raw leachate is very complex,after treated by the biochemical combined with ultrafiltration method, the effluent is still containing lots of pollutant soluble organic pollutant(DOM).After measuring the effluent, the index of the COD is between 450 ~ 550 mg/L,which still cannot meet the primary level emissions standards of "Integrated wastewater discharge standard"(GB8978-1996).Thus, the factory further uses Reverse Osmosis technology for advanced treatment, the process can quickly achieve the effluent’s purification and enrichment. Due to high salt content in the leachate, reverse osmosis membrane often trends to blocking phenomenon, and the processing efficiency will reduce gradually over time, and if frequently replacing the reverse osmosis membrane the cost will greatly increase. In addition, we collected the effluent samples to test, and found that the COD concentration is about 105 mg/L, which cannot be stable to achieve corresponding sewage discharge standard in China.Therefore, this topic used the garbage leachate before OR process as experimental object, exploring treatment effect and mechanism of electrolysis process combined with chemical coagulation about the organic pollutants in the wastewater.Paper analyzes the optimal process parameters of these two kinds of process, and then using Three-dimensional Fluorescence and FT-IR to analyze the main mechanism the process.In this paper, the main conclusions are as follows.① Aluminum plate electrode’s COD treatment effect is better than iron plate’s.② Using the chemical coagulant polyaluminium chloride(PAC) to treat the reverse osmosis’ s entering leachate, under the condition of initial p H = 6, PAC dosing quantity 1600 mg/L, PAM dosing quantity 5 mg/L,the maximum COD removal efficiency can reach 35.65%;When using the electrochemical processing to treat the effluent, at the initial p H=5, electrolytic time 5 min, initial voltage 40 v, 3mm plate spacing, the best COD removal rate can reached 66.29%;When combined the above two methods to deal with the leachate, under the same conditions, the COD efficiency was 56.33% after using the process of chemical coalgulation+electrolytic treatment, and the COD has a higher removal efficiency about 65.28% when using electrolysis treatment + chemical coagulation.③ Using the three-dimensional fluorescence to analysed the entering and the discharging leachate of the OR,we can see the entering leachate containing lots of high molecular, complicated structure, relatively stable kind of fulvic acid material, and humic acid soluble materials. These organisms were all difficult or not biodegradable organic matter, and the waste water presents a high humification degree at this stage. Secondly, reverse osmosis technology cannot completely remove fulvic acids, but it can be a very good way to remove the humic acid substances in the water.④ Using the three-dimensional fluorescence to analysed the leachate treated by electrolysis and chemical flocculation process, the macromolecular substances in the effluent, such as aromatic structure or unsaturated conjugated system, can certain extently be destroyed, and the aromatic hydrocarbon compounds also trends to decrease. But this method cannot significantly reduce or remove all macromolecular organic matter. The electrolyte was further treated by chemical coagulation; the coagulant increased the stability of conjugated system in wastewater. At the same time, in the processing of the chemical coagulation tryptophan fluorescence peak was appeared, which showed that using this method may improve the biological degradability.⑤ Using the FI-IR to analysed the sediment produced during the process of electrolysis and chemical coagulation method, we can see the organic matter in leachate, such as aromatic, aliphatic compounds, the amide material, carbonyl compounds and so on all have removal effect. But in terms of removing aromatics and amide compounds, chemical coagulation method’s treatment effect is better than electrolytic process alone. In addition, as-OH stretching vibration peaks in spectra is the strongest, it showed that in this experiment,either the electrolytic process or chemical coagulation method, the main removal mechanism of the organic matter in waste leachate was coagulation precipitation effect. In addition, the process accompanied with electrode oxidation.