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Constructed wetlands system because of its various advantages, such as its lowinvestment and operating costs, wide range of applications, stable quality of drainage water,ecological and energy saving, etc; So it is respected by water treatment workers. CWS hasbeen widely used in various fields, such as domestic sewage, industrial wastewater, eutrophicwater. However, the single type of CW has some shortcomings, such as easy to plug, lowdissolved oxygen levels in the wetland, limited capacity in removal of pollutants, strictrequirements of influent water and other shortcomings. In this paper, through the pilot studyof the deeper anaerobic pond and micro-aeration as the pretreatment of CWS, analyze andsummarize the characteristics and influencing factors of each process, and studied the effectof combination process in domestic sewage treatment.First, experiments on deeper anaerobic pond and constructed wetland, the experimentsshowed that the anaerobic pond could start in a short period of time by adding manure;constructed wetlands can also be quick start in a month by transplanting plants anddischarging into the tap water.Secondly, experiments on the level of dissolved oxygen in the anaerobic pond and itsinsulation effect, tests showed that the anaerobic pond has good insulation effect, in winter thetemperature can be maintained at14-15℃; addition, it can maintain a low level of dissolvedoxygen in the pond, the level of dissolved oxygen in the depths can be lower than0.2mg/L.Experiments on different hydraulic loading and pollution load conditions, tests showed thatthe anaerobic pond removal gradually decreased with increasing hydraulic loading, so thepond in the experiments has a lower hydraulic loading, because the volume of anaerobic pondis small; however, when the pollutant load is high, the removal of anaerobic pond is better, sothe anaerobic pond is suitable for high concentration wastewater.Then, experiments on the factors of constructed wetland treatment. Tests showed that theconstructed wetland effluent pollutant concentration gradually increasing with increasinghydraulic loading, hydraulic loading to0.1m/d, water can only reach 《Technical specificationof constructed wetlands for wastewater treatment engineering (GB18918-2002)》 as a Bstandard, the load in the test is lower than in most practical engineering, but when the area ofconstructed wetland is large enough, the load capability of the system can be better; Theamount of pollution removed by the two wetlands and the volume of pollution of the influentwater showing a better line relationship; through pre-aeration test showed that this methodcan not be effective in improving the level of dissolved oxygen in the wetland, but it can beeffective in improving the influent water quality; at the same time,the two wetlandsexperiments showed that the vertical flow wetland have a better treatment result. Finally, To test the treatment effect of the combination system, tests showed a good resultin removal of pollutants, but due to the high influent nitrogen levels, nitrogen removalcapacity is limited, the result is not ideal in removal of nitrogen. In addition, the constructionof greenhouses in winter showed better insulation effect.
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