Research On Wastewater Treatment By Technology Of Divisional Influent ABR-Multi-stage Vertical-flow Constructed Wetland

This paper started with the practical wastewater treatment purposes, selected threekinds of typical wastewater, domestic sewage, aquaculture wastewater and landfillleachate, as the research objects, through the treatment of the three kinds of wastewaterby divisional influent ABR-multi-stage vertical-flow constructed wetland, theremoval efficiency and mechanisms were investigated for COD and NH₃-N, TN, TPand other major pollutants, the optimal operating conditions and parameters of thesetechnology were discussed. Besides, according to the experimental results, this workalso summarized the characteristics of divisional influent ABR and multi-stagevertical-flow constructed wetland for wastewater treatment and also revealed thefeasibility of wastewater reuse for agricultural irrigation using the two-stage process ofdivisional influent ABR and multi-stage vertical-flow constructed wetland technologyfrom a technical point of view. The results could provide technical support for theengineering applications of divisional influent ABR and multi-stage vertical-flowconstructed wetland technology in domestic sewage, aquaculture wastewater andlandfill leachate treatment.The results showed that the innovative design divisional influent ABR caneffectively reduce the organic load of the first cell of the reactor chamber, enhance thecapability of hydrolysis and acidification, significantly reduce the start-up time, andimprove the processing performance of the reactor. Meanwhile, the multi-stagevertical-flow constructed wetland changed the wastewater flow state, increased thecapacity utilization, optimized the function of the aerobic zone and anaerobic zone inthe wetland, strengthened the nitrification and denitrification effect, and improved theprocessing capacity of the wetland.The divisional influent ABR-multi-stage vertical flow constructed wetland wereused for treatment of domestic sewage; the optimal hydraulic retention time （HRT） fordivisional influent ABR and wetland were6h and1.5d separately. By divisionalinfluent ABR the removal efficiency of COD maintained at an average of34.5%, withthe maximum of44.2%. Multi-stage vertical-flow constructed wetland was followed, in winter the removal rate of COD, NH₃-N, TN and TP were in the range of70.7%-83.1%,53.60%-75.3%,72.5%-84.9%and55.8%-82.5%respectively; and insummer the removal rates of COD, NH₃-N, TN and TP were in the range of87.3%-96.1%,78.2%-86.1%,94.4%-95.1%and81.8%-89.6%separately. After thetwo-stage treatment, the maximum concentrations of COD, NH₃-N, TN and TP in thefinal effluent in winter were59.81mg/L,24.16mg/L,23.13mg/L and9.70mg/L; whilein summer the corresponding concentrations could be as low as7.36mg/L,6.54mg/L,3.64mg/L and2.81mg/L respectively.The divisional influent ABR-multi-stage vertical-flow constructed wetland wereused for treatment of aquaculture wastewater, the optimal HRT for divisional influentABR and wetland was8-12h and3d separately. By divisional influent ABR theremoval efficiency of COD was35.0%-41.3%. Multi-stage vertical-flow constructedwetland was followed, in winter the removal rate of COD, NH₃-N, TN and TP were inthe range of71.6%-86.4%,69.8%-77.5%,68.0%-79.6%and64.3%-71.2%respectively; and in summer the removal rates of COD, NH₃-N, TN and TP were in therange of89.2%-93.9%,86.4%-91.2%,86.5%-89.4%and78.6%-85.6%separately. Themaximum and minimum removal rate of COD, NH₃-N, TN and TP were in August andJanuary separately.The divisional influent ABR-multi-stage vertical-flow constructed wetland wereused for treatment of landfill leachate, the optimal HRT for divisional influent ABRand wetland was12h and3d separately. By divisional influent ABR the removalefficiency of COD was33.1%-36.7%. The removal trends of following multi-stagevertical-flow constructed wetland for the pollutants in landfill leachate weresignificantly different with that for domestic sewage and aquaculture wastewater, inlate July the removal efficiency of pollutants tended to decrease. After the two-stageprocess of divisional influent ABR and multi-stage vertical-flow constructed wetlandthe removal rate of COD, NH₃-N, TN and TP in landfill leachate were73.5%-91.5%,62.6%-84.2%,59.7%-83.9%and71.5%-84.4%. Reed had stronger absorption capacityfor Zn²⁺than Cu2+; wetlands had significantly different removal efficiency for Zn²⁺inwinter and summer.The divisional influent ABR-multi-stage vertical-flow constructed wetlandtechnology had better treatment effect on typical high or low concentration of organicwastewater. The divisional influent ABR reactor improved the capability of hydrolysis and acidification; multi-stage vertical-flow constructed wetland enhanced thenitrification and denitrification effect. Domestic sewage after treatment by thetwo-stage process of divisional influent ABR-multi-stage vertical-flow constructedwetland could reach the standards of agricultural irrigation.