| The control of non-point source pollution in rural areas is the most significant part of the current defending fight to keep our water clear in China,and agritainment sewage is an important part of it.Agritainment is a new form of tourism and recreation integrating catering,entertainment and accommodation that originated from Chengdu in the Sichuan Province of China.Agritainment attracts a large number of urban residents,which not only promotes the development of local society,culture,economy and tourism,but also poses a huge risk to the local ecological environment.Agritainment is scattered and a huge amount of sewage produced by tourists' eating,drinking and playing cannot be collected and treated uniformly,which makes sewage treatment more difficult.At present,there are few researches on the characteristics and treatment process of agritainment sewage discharge.In view of this,it is of great practical significance to find out the basic characteristics of agritainment sewage discharge and develop the treatment process for agritainment sewage.This paper takes agritainment in Sichuan province as the representative,the questionnaire surveys were carried out on the characteristics of sewage discharge from 280 agritainment sites in 15 cities,among which 25 surveyed sites were monitored for sewage quantity and quality,and a Garden Restaurant was selected as a model to monitor the characteristics of sewage quality for a year.Based on the model of the Garden Restaurant sewage,the technology of “Homogenize tank+ Oil separating tank+ Purification tank + Constructed wetland” was studied to treat agritainment sewage.The research provides the basic data and reference for the management of agritainment sewage discharge,and the main conclusions are as follows:(1)The characteristics of agritainment sewage discharge in Sichuan province are found out and the prediction model of agritainment sewage discharge is established.In general,the proportion of direct sewage discharge is relatively high,the discharge sewage volume is large and the sewage quality is poor with huge fluctuation.It was found that 5.3%agritainment sites discharged toilet sewage directly while 25.3% of sites discharged kitchen wastewater directly into the environment.The average annual sewage discharge volume of agritainment is 2.48 million L,and the ratio of average sewage discharge volume to agritainment operating income is 9.24 L/yuan.According to the correlation between the sewage discharge volume and the operating income of agritainment,the prediction models of agritainment sewage discharge in different types were established(Hot pot:y=5.74x+24834;Barbecue:y=20.1x-136341;Chinese food:y=11.3x-1847),which is of great important to fully understand the risk of agritainment sewage discharge.The main pollutants in Sichuan agritainment sewage were total suspended solids(10-2470 mg/L),total phosphorus(0.07-17.1 mg/L),chemical oxygen demand(144-2580 mg/L)and anionic surfactant(3.5-411mg/L),which are more serious in autumn and winter than in spring and summer.(2)The technological process of "Homogenize tank + Oil separating tank + Purification tank + Constructed wetland" has evident effect on the agritainment sewage treatment.The purification tank is a classic equipment for the treatment of decentralized domestic sewage,but the research shows that the process of “Homogenize tank + Oil separating tank +Purification tank” is not stable without satisfactory treatment effect.It has great effect on the removal of COD and ammonia nitrogen with the highest removal rate of 81% and 68%,respectively;meanwhile,the removal rate of total phosphorus is less than 50%.In order to achieve high effect treatment of agritainment sewage,vertical flow constructed wetland is connected to the outlet of purification tank for advanced treatment.The result shows that the vertical flow constructed wetland has obvious effect on the deep removal of TP and COD,with the highest removal rate of 63% and 86% respectively.Moreover,the effluent quality is stable,both of which can reach the discharge standard of water pollutants for rural domestic sewage treatment facilities in Sichuan Province(DB51/2626-2019 Level II)and the discharge standard of pollutants for municipal wastewater treatment plant(GB18918-2002 Level IB)... |
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