Researches on Classification Features of Rural and Urban Domestic Waste in Tianjin City Under Secondary Classification Mode

Haitian LlANG，Xianbiao GAO，Zongjun HE，Yan Ll，Di WU，Defang WANG，Shan QlAN，Yuhua Ll

Tianjin Institute of Agricultural Resource and Environmental Science，Tianjin 300192，China

Researches on Classification Features of Rural and Urban Domestic Waste in Tianjin City Under Secondary Classification Mode

Haitian LlANG，Xianbiao GAO*，Zongjun HE，Yan Ll，Di WU，Defang WANG，Shan QlAN，Yuhua Ll

Tianjin Institute of Agricultural Resource and Environmental Science，Tianjin 300192，China

In order to investigate the influence of secondary classification mode on waste generation features，this study classified domestic waste generated by 310 rural and urban households at urban areas and Shuigaozhuang Village of Xiqing District into 3 groups:compostable materials，recyclable materials and toxics on the basis of the constructed secondary classification mode of domestic waste.The study focused on waste generation strength and classification features，compared the waste generation features between rural and urban residents，and analyzed the relation between waste generation strength and economic and cultural factors.The results indicated that the average generation speed of urban domestic waste was 423.08 g/（d·capita），and that of rural domestic waste was 629.89 g/（d·capita），there was significant difference between rural and urban compost generation strength （P= 0.00002），while the generation strength of recyclable materials and toxics between rural and urban areas had no significant difference （P=0.471 andP=0.099，respectively）.Secondary classification mode is an effective source classification mode for domestic wastes and has positive effects on waste reduction and treatment.

Secondary classification mode；Domestic waste；Compostable materials；Classification features；Generation strength

P rotection of rural environment is related to the quality of most farmers’lives，while a series of rural environment problems have been caused by the extensive economy growth mode in rural areas and ignorance to the value ecological environment［1-2］.Waste problem is a worldwide problem，and rural waste problem has always been one of the important problems that perplex rural development in China，concerns the vital interests of farmers and the sustainable development of agriculture and rural areas and must be solved in the process of new rural construction.

Differentwith urban domestic waste，the generation features of rural waste could reflect various information including local living habits，humanistic characteristics and economic conditions［3-5］.With the new rural construction in China，farmers’living standard has been improved with the accompany of increase in amount of rural domestic waste，and the domestic waste generated in rural areas in China was about 7 500 000 t per annum according to the amount of domestic waste generated by rural residents as 0.6-0.8 kg per capita daily.Owing to relatively-weak rural environment infrastructures，rural areas are in lack of the collection and transportation facilities for domestic waste，the waste management system is immature，and stacking rural waste at will is very common，resulting in dirty，disordered and poor hygienic conditions in rural areas［6］.With rapid improvement in living standard of rural residents and increasing emphasis on rural environment and food safety problems in China，waste classification treatment experiments have been conducted in Beijing，Jiangxi，Henan，Zhejiang，Hainan and so on，to explore suitable local waste treatment modes，and certain effect has been obtained［7-9］.Most of these modes are recycle of organic matters in waste in two manners，of which one is compost and the other one is marsh gas production［10-13］.However，owing to differences in factors including territory and economic conditions，most of these treatment modes are in the situation of shrinkage even abandonment，andthuscould not solve the problem of rural waste treatment and elimination，leaving still severe environment pollution.There are following reasons:the selected treatment mode is not suitable for practical requirements；halfway waste classification restrains subsequent treatment process；the third one is restriction by economic factor；and the technical services fall behind［14-15］.Consequentially，establishing resource management mode of rural domestic waste suitable for local situation and capable of operating sustainably is a sustainable rural waste treatment way capable of realizing quantity reduction，harmless treatment and resourcelization of waste，and plays an important role in improving rural environment quality and rural environment sanitary condition［16-18］.

The secondary classification mode has been experimented in rural areas of Tianjin［19-21］.This study compared the generation features of rural and urban domestic waste under the secondaryclassification mode with peasant households as the starting point，and identified the generation strength，componentcharacteristics and influence factors of urban and rural domestic waste.The proposed classification treatmentmode has been acknowledged by vast farmers，achieved a good effect，and has important guiding significance for the sustainable development of agriculture，rural areas，farmers and whole society of China，improvement of rural ecological environment and comprehensive construction of new socialist countryside.

Table 1“Two barrels and one net cage”classification method for domestic waste

Materials and Methods

General situation of study area

Rural demonstration area Shuigaozhuang Village of Tianjin City is located at Xinkou Town of Xiqing District，with 1 772 households in total，having a total population of about 6 000.

Shuigaozhuang Village is one of pilot villages and towns for rural waste treatment of the inter-governmental cooperative projectby China and Canada，in which domestic waste was subjected to classified treatment by the secondary classification mode of“household classification， village transportation，station treatment”and aerobic biological treatment technique. The waste classification investigation was set at the typical demonstration plot of waste classification in the village，which occupied an area of 4.5 hm2，involving 190 farmer households. The Rural per capita net income in the demonstration plot was 2.5×104Yuan/year，at the average level of rural areas in Tainjin，and the main sources of income were greenhouse vegetable cultivation and taking jobs in cities.

Urban demonstration area In order to compare the domestic waste generation features between rural and urban residents，the study selected 120 urban households，which were located at 6 districts of Tianjin，respectively，with an urban per capita net income of 6.5× 104Yuan/year，at the average level of the urban areas of Tianjin，and the main source of income was working as employee in companies.

Study method

Domestic waste classification mode： secondary classification method The domestic waste generated in daily life by the rural and urban households participating in this study was classified at home by the secondary classification mode of“two barrels and one net cage”，and the classification way was shown in Table 1.The secondary classification mode took household as unit，and classified domestic waste generated in daily life into compostable materials，recyclable materials and toxics.The compostable materials referred to the substances which could be converted into organic soil by fermentation，rot and degradation under the action of microorganisms.The recyclable materials referred to the waste which could be separated，recovered and processed conveniently.The toxics were substance containing complex chemical components and heavy metals which caused pollution to environment and were harmful to human health，and articles which were dangerous in treatment process，increased treatment difficulty and affected the product formed in waste treatment.The classified domestic waste could be collected according to compostable material collection barrel，recyclable material collection barrel and toxic collection net cage，and collected and transported by cleaners at regularintervals.The compostable materials and recyclable materials were transported to eco-stations and waste treatment plants for classified treatment，and the toxics were transported to special treatment mechanisms to perform treatment.

lnvestigation method for generation features of typical domestic waste This study investigated the outputs and features of various kinds of domestic waste generated by rural and urban residents for 8 months continuously from November of 2013 to June of 2014，and the 310 households participating in this investigation lived in urban areas and shuigaozhuang Village，Xinkou Town，Xiqing District. Among them，190 households lived in ruraldemonstration plot，and 120 households were urban residents.

The domestic waste generated by the residents participating the investigation was collected by the secondary classification mode，i.e.，the residents classified the domestic waste generat-ed in daily life by themselves into such three classes as compostable materials，recyclable materials and toxics，which were put into compostable material collection barrels，recyclable material collection barrels and toxic collection barrels，respectively，and further classified the recyclable materials into such five sub-classes as paper，plastic，metals，glass and fabrics，which were weighed on electronic scales in the evening of each day.The data was recorded in tables，which were collected once a week to perform summary statistics.The classified recyclable materials and toxics were collected and investigated.After the investigation，the residents participating in it were rewarded.

Data analysis

The statistic analysis of domestic waste generation strength adopted one-way analysis ofvariance by SPSS.Data and tables were processed with Excel 2007 and OriginPro.

Results and Analysis

lnvestigation of generation strength of rural and urban domestic waste

Fig.1 showed that during November of 2013 to June of 2014 in rural and urban demonstration plots，the average generation speed of urban domestic waste was 423.08 g/（d·capita），and that of rural domestic waste was 629.89 g/（d·capita）.The investigation result of rural and urban domestic waste showed that the amount of domestic waste generated by urban residents was remarkable lower than the amount of domestic waste generated by rural residents.This difference was due to the fact that the compostable materials generated by urban residents were less than that generated by rural residents，which might be related to the living habits of rural and urban residents.Most compostable materials in domestic waste are kitchen waste，while most fruits and vegetables purchased by urban residents are processed commodities，the inedible parts or rotten leaves of which have already been removed in harvest and circulation process，resulting in reduced percentage ofdiscardable parts.Rural residents have the characteristic of producer of agricultural products，and the percentage of compostable materials in domestic waste thus might increased.

Feature identification of domestic waste generated by rural and urban demonstration households

Feature identification of the three classes of rural and urban domestic waste under secondary classification mode Fig.2 showed the differences in the amounts of the three classes of rural and urban domestic waste after classification according to the secondary classification mode. The daily domestic waste generated by rural and urban residents was compostable materials mainly，specifically，the average generation speed of rural compostable materials was 510.99 g/（d·capita），accounting for 81.12%of the amount of domestic waste，and the average generation speed of urban compostable materials was 330.89 g/（d·capita），accounting for 78.21%of the amount of domestic waste.The next was recyclable materials，specifically，the average generation speed of rural recyclable materials was 103.53 g/（d·capita），accounting for 16.44%of the amount of domestic waste，and the average generation speed of urban recyclable materials was 86.83 g/（d·capita），accounting for 20.52%of the amount of domestic waste.The average generation speed of rural toxics was 15.38 g/（d·capita），accounting for 2.44%of the amount of domestic waste，and the average generation speed of urban toxics was 5.34 g/（d·capita），accounting for 1.27%of the amount of domestic waste.The results of statistic analysis showed there was significant difference between the generation strength of rural and urban compostable materials（P= 0.000 02），while the generation strength of recyclable materials and toxics between rural and urban areas had no significant difference（P=0.471 andP= 0.099，respectively）.

Under secondary classification mode，the generation features of the three components of rural and urban waste reflected the difference between lifestyles of residents to certain degree.The amount of recyclable materials generated by residents participated in the investigation showed that the average output of recyclable materials by ruralresidents was 103.53 g/（d·capita），which was slightly higher than that of 86.83 g/（d·capita）in urban areas，while the statistic analysis showed there was no significant difference （P=0.471），which might be related to the factthatthe rural demonstration plot selected for this investigation is located at the suburb of Tianjin，where the economic is developed，resulting in little difference between lifestyles of rural and urban residents.

The average output of toxics by rural residents was 15.38 g/（d·capita），which was slightly higher than that of 5.34 g/（d·capita）by urban residents. This result might be related to agricultural chemicals used in agricultural production.The investigation showed that，the domestic waste of rural residents showed a higher proportion of discarded pesticide bottles and pesticide bags，with other types of toxics less observed，while the toxics in the domestic waste of urban residents were a few batteries and small electronic products.It was thus clear thatthere was obvious difference between types of toxics generated by rural and urban residents，and the rural residents generated more toxics than urban residents.However，the statistic analysis showed there was no significant difference （P=0.099），which accorded with the difference between lifestyles of rural and urban residents.

Feature identification of rural and urban recyclable materials under secondary classification mode

The average outputs of recyclable materials in rural and urban domestic waste were 86.83 g/（d·capita）and 103.53 g/（d·capita），respectively，without significant difference in statistic analysis（P=0.471）.Fig.3 showed that recyclable materials in domestic waste were further divided into five classes，i.e.，paper，plastic，metals，glass and fabrics，the amounts and features of which were also shown.The average outputofpaperin ruraldomestic waste was 33.87 g/（d·capita），which was slightly lower than that of 40.75 g/（d·capita）in urban domestic waste，and there was no significant difference by statistic analysis（P=0.584）；plastic had an average output in rural domestic waste of 21.38 g/（d·capita），which was slightly lower than that of 23.14 g/（d·capita）in urban domestic waste，and there was no significant difference by statistic analysis （P= 0.815）；in the case of metals，the average outputin ruraldomestic waste was 11.61 g/（d·capita），which was slight higher than that of 2.17 g/（d·capita）in urban domestic waste，and the statistic analysis showed that there was no significant difference（P=0.081）；the average output of glass in rural domestic waste was 14.87 g/（d·capita），which was slightly lower than that of glass in urban domestic waste as 15.69 g/（d·capita），and statistic analysis showed that there was no significant difference between them （P=0.910）；and when it came to fabrics，the average output in domestic waste was 21.79 g/（d·capita），which was slightly higher than 5.09 g/（d·capita）in urban domestic waste，and the statistic analysis showed there was a significant difference between them（P=0.007）.The investigation results showed that there was no significant difference between total outputs of recyclable materials in rural and urban domestic waste，the generation features of various components were not significantly different substantially as well，and therefore，recyclable materials in rural and urban domestic waste were not the main factor influencing the total generation strength of domestic waste.

Conclusions and Discussion

（1）The investigation results of typicalruraland urban residents showed that the average outputs of rural and urban domestic waste were 423.08 g/（d·capita）and 629.89 g/（d·capita），respectively，among which the output of compostable materials was the main factor influencing the total generation strength of domestic waste despite of still higher domestic waste generated by rural residents.Due to the difference in lifestyles of rural and urban residents，the generation features of recyclable materials and toxics were different，but were not the main factors influencing the total generation strength of domestic waste.The differences in the generation features of rural and urban domestic waste indicated that the secondary classification mode of“two barrels and one net cage”was more suitable for the classified treatment of domestic waste in rural areas.Therefore，such reduced-amount treatment and recycling mode，by which the domestic waste is subjected to classification of “two barrels and one net cage”at sources and compostable materials are isolated for separate treatment by performing aerobic bioconversion treatment at eco-stations to produce high-quality organic soil for resource recycling，is more suitable for rural areas than the treatment ways for urban domestic waste.

（2）The lifestyles of rural and urban areas are remarkably different，and significantly affect implementation of waste classification，mainly in that: rural residents have relatively fixed living areas for generations，and posses more close common interests in the aspects of the effects of waste to soil，underground waste and food safety；rural households are associated with each other，while urban residents are relatively independent，i.e.，the behaviors of rural residents were affected by local customs and the behaviors of neighbors more easily；and rural residents were more concentrative，with convenient organization and management.As a result，the secondary classification mode ofdomestic waste could be popularized and accepted more easily in rural areas.

（3）The secondary classification mode ofdomestic waste is an effective management mode.Performing classified collection and classified treatment on the domestic waste generated in rural area of Tianjin by the secondary classification mode of“two barrels and one net cage”could classify domestic waste at its sources，which is beneficial to realization of quantity reduction，harmless treatment and resourcelization of domestic waste，thus reducing harm of domestic waste to rural ecological environment and promoting safe production of agricultural products.This mode could reduce buried waste by 93.5%，and the aerobic bioconversion rate is above 70%.The rural waste treatment mode of classifying and collecting waste in unit of household，performing united collection and transportation in unit of village and establishing medium and smallscale centralized treatment nearby could improve the efficiency of comprehensive waste treatment and reduce cost，providing an example for classification and treatment mode of rural domestic waste in China.This mode is one of the demonstrative modes for domestic waste treatment in rural areas of Tianjin，as well as guiderules for treatment of rural waste in Tianjin are enacted for popularization，setting an example in Tianjin.Meanwhile，this mode has been accepted by rural residents gradually as it is suitable for practical conditions of rural areas and has the characteristic of convenient propaganda，further improves the environmental awareness of rural residents，and generates long-term socialbenefit and socialbenefit. Therefore，the secondary classification mode of domestic waste is a kind of resourcelizationmanagementmode for rural domestic waste suitable for rural social，economic and cultural conditions as well as natural condition and capable of operating sustainably.

In conclusion，the treatment of rural domestic waste is not only a technical problem，but also a social problem.It is necessary to enhance the popularization of the scientific knowledge about waste classification and environment protection with the assistance of incentive measures，to thereby promote rural waste classification and improve rural environment as well as humanistic quality，and the sustainability of classification and treatment of rural domestic waste could be realized only by solving the problem of fund for construction and operation maintenance from various aspects.

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Responsible proofreader：Xiaoyan WU

二级分类模式下天津市城乡生活垃圾的分类特征研究

梁海恬，高贤彪*，何宗均，李妍，吴迪，王德芳，钱姗，李玉华 （天津市农业资源与环境研究所，天津 300192）

为了研究生活垃圾二级分类模式对垃圾产生特征的影响，以天津市区和西青区水高庄村共310户城乡居民为研究对象，依托已经建立的生活垃圾二级分类模式，将生活垃圾分为可堆腐物、可回收物和有毒有害物3类，重点调查居民生活垃圾的产生强度及分类特征，对城乡居民生活垃圾的产生特点进行比较，并分析生活垃圾的产生强度与经济、文化等因素的关系。结果表明，城市生活垃圾平均产生强度为423.08 g/（d·人），农村生活垃圾平均产生强度为629.89 g/（d·人）；可堆腐物产生强度城乡之间呈现显著差异（P=0.000 02），可回收物和有毒有害物的产生强度城乡之间未呈现显著差异，分别为P=0.471和P=0.099。二级分类模式是有效的生活垃圾源头分类模式，对垃圾减量处理起到积极的作用。

二级分类模式；生活垃圾；可堆腐物；分类特征；产生强度

天津市农业科技成果转化与推广项目"农村垃圾和生活污水处理与利用技术示范"（201003010）。

梁海恬（1980-），女，天津人，助理研究员，硕士，主要从事固体废弃物利用技术研究，E-mail：haitianlan1017@163.com。*通讯作者，研究员，主要从事农村环境生物保护研究，

2015-08-30

Supported by Agricultural Scientific and Technological Achievement Transformation and Popularization Project of Tianjin（201003010）.

*Corresponding author.E-mail:soils@163.com.

Received:August 30，2015 Accepted:December 3，2015

E-mail：soils@163.com。

修回日期 2015-12-03