IEEE EDUCON 2024 - Global Engineering Education Conference

2.2.4.2 Garbage transportation

Two types of transit vehicles, one is electric vehicle with four garbage bins (Fig.6) and one with trash can with special number (Fig.7), were used for transportation of campus garbage. The vehicle with four bins is mainly responsible for transportation of residential garbage and these four bins will be filled with kitchen waste, recyclable waste, and other garbage respectively. Staff will do a simple classification to correct the wrong classification from each garbage bin printed with a mark named by logistic departments of Beihang. The other one is mainly responsible for the wastes from office area, teaching area and campus roads and landscape area, and cafeteria and laboratory waste will be transported separately by the vehicles with special numbers printed on it.

2.2.4.3 Processing of garbage recycling station in green campus of Beihang University

In order to implement green campus in Beihang University, garbage recycling station must have the following features: less occupied area, fully enclosed, no undesirable odor, and little impact on the surrounding environment, advanced waste classification and processing facilities.

As shown in Figure 2, garbage is transported to Beihang garbage recycling station where the first step is to weigh garbage and then the transported garbage are mixed to do first manual screening for selection of recyclable waste, such as plastic bottles, paper and white plastic bags. After the first screening, the garbage will be screened again by wind machine. The rest garbage can be categorized mainly into the followings: light weighed rubbish, compostable waste and garbage required to undergo secondary screening. Light weighed rubbish is screened in the conveyor by blowing with wind from above to continue the secondary manual selection, compostable garbage will be processed in pulverizer to become compostable material, while the rest garbage will be continued for secondary screening along the original conveyor, and finally, garbage will be compressed and packaged to finish completely the secondary screening.

Leachate generated during waste processing will be transferred to the sewer treatment through plash pumps of garbage recycling and processing station, and then it will be treated along with the sewage.

Garbage recycling and processing station also has a suction outlet that relates to biological deodorization reactor by piping. While the processing of garbage is running, workshop and all internal devices are all in the vacuum state to ensure that the undesirable odor cannot leak. The undesirable odor is collected to be deodorized by biological deodorization reactor. For deodorization process of undesirable odor of garbage, the smell generated in vacuum state will be inhaled by suction outlet to transport to biological deodorization reactor, and then deodorizing filter layer will "capture" and "fixed" the undesirable odor. Microbes in the filter will decompose and synthesize these undesirable odors to become carbon dioxide, water, and a trace amount smell. Finally, the odor will be discharged from air-vent after passing through gas processing in biological deodorization reactor.

In the garbage recycling and processing station, kitchen waste is not allowed to be mixed with other garbage; the kitchen waste from canteen will go directly into hogwash machine for being composted in order to make organic fertilizer. For this treatment process of kitchen waste, degreasing step must be done to remove the oil from food waste and this removed oil are not suitable as edible for no longer and so these oils will be transported to factory for making biodiesel fuel in order to provide energy.

According to statistics Table 1 The total daily waste production from per capita waste production is 21.4 tons. By monitoring result the daily disposal rate of the four types of waste as shown in Figure 2. The perishable amount reached to 53% of total amount of garbage processing can be accounted as the largest. All types of waste proportion for the total amount of garbage processing were shown in Table 2.

Table.2 Proportions of various waste from garbage processing

Currently, the perishables are transported to recycling center for organic resources in Sijiqing where these wastes collectively with feces and landfill leachate, will be transformed into biogas, bio-organic fertilizer, and other renewable resources. The recyclable materials will be transported to the recycling market. And thus, two parts of garbage material can be eventually converted into renewable resources. It has proved that 59 percent of campus living garbage achieved resourceful treatment in Beihang green campus processing station. The utilization of campus garbage as "resources" can be greatly improved by doing this practice.

3. According to the experimental results, the students summed up the problems needed to counteract for improvement of garbage classification system

3.1 Less knowledge and accuracy rate of garbage classification

Residents are lack of professional knowledge in garbage classification. The residential garbage has many categories and their components are complex. Only few categories of garbage can be roughly classified. As an example, some residents do not know that battery, thermometer etc. are toxic and harmful, and so they will discard these toxic and hazardous waste with recyclable waste together into the trash bin. Because of this, these hazardous wastes will contaminate the recyclable waste and thus the campus waste resource utilization ratio will decline significantly. Therefore, it’s important to define various types of garbage. To define these wastes, the first thing to consider is the cost of garbage follow-up process [3], and the second thing is the value of recovered recyclable waste. For example, a clean newspaper and a clean plastic bag can be classified as recyclable garbage, but oil-soaked newspapers and plastic bags full of food should be assumed as other waste to deal with. If the cost of recycling is more than its recovered value, waste classification would change with it.

3.2 Bad garbage classification

For residents in the campus, there are only two kinds of garbage classifications bins for kitchen waste and other garbage, and for campus area, garbage bins are only three categories including kitchen waste, recyclable waste, and other garbage. Hazardous waste classification is not included in these categories. If residents have hazardous waste, such as batteries, thermometers, and lamps, they will put these hazardous wastes to recyclable waste bins, and so, it can cause these recyclable wastes to be contaminated and can no longer to be recycled. This can cause not only a waste of resources but also a certain risk for people`s health and the surrounding environment.

3.3 Incomplete facilities for garbage classification

3.3.1 Indoor garbage bins did not match with outdoor garbage bins

According to garbage bins shown in Fig 3 and Fig 4, for residents, the garbage bins inside buildings did not match with the garbage bins outside buildings; there are three trash classification bins outside the buildings compared to trash bins inside lack of trash bin for "recyclable waste". Because of this, it is easy to become residents confused about classification of residential garbage and so, they cannot make accurately classification of garbage. On the other side, the recyclable garbage from indoor garbage bins of household cannot be recycled very well resulting in a waste of resources.

3.3.2 Lack of necessary facilities conducing garbage classification

Inside the dormitory of Beihang University, there is no garbage classification bins and so students put the mixed garbage into a trash can. Then, this mixed garbage will be classified by the staff. This can cause not only greatly increase in workload for garbage classification but also reduce the resources for utilization of recyclable waste.

3.4 Imperfection of garbage collection, transportation, and processing systems

After treating the campus garbage in garbage treatment station of Beihang green campus, the treated garbage has only two possible ways, landfilling and composting, in the end of the process. There is no garbage that can be sent to garbage incineration plant for incineration process. It has indicated that garbage is not classified very well, processing system is imperfect, and this will result in wasting of some recyclable garbage and imperfect recycling of garbage.

3.5 Lack of publicity and public awareness in garbage classification

Publicity for garbage classification pilot generally stays in traditional ways and simple forms of garbage processing. Before performing activities for public awareness of garbage classification, it is very important to consider the limited scope of residential areas. As an example, while giving trash bins and plastic bags to residents, simply explanations of how to classify garbage to residents cannot play the role of publicity for introduction of garbage classification. And if there is no publicity of garbage classification in dormitory and other places, it could fail to guide public to understand the meaning of garbage classification. If the time for activities of public awareness is short, this can result in less effectiveness on classification of campus garbage, and so a certain effect of publicity cannot be achieved.

4. According to the experimental results, the students summed up the countermeasures for garbage classification and processing system

4.1 Scientific formulation of garbage classification

Garbage classification method should have strong inclusiveness, easy defining characteristics and good adaptability, which should relate to regional and social conditions, treatment facilities, public awareness, waste composition and so on. According to the status of Beihang campus garbage classification pilot, the garbage should be divided into the following categories.

(1) Recyclable waste: it refers to the garbage that can be recycled, used again, and must have low cost for recycling. It usually refers to the goods that can be recycled as long-term renewable resource in recycling site. It includes: (1) non-severely tarnished paper, such as newspapers, magazines, packaging cartons, paper plates, etc., (2) non-severely tarnished plastic, such as various clean plastic bottles, plastic foam packaging, and rigid plastics and so on, (3) metal, such as cans, tin cans, etc. and (4) glass: such as bottles and so on.

(2) Kitchen waste: food residues, leaves, offal from meat, pericarp and kernel of foods, waste food, etc. which are mainly consisted in school canteen garbage. These kitchen wastes can be processed to make organic fertilizers by microbial fermentation.

(3) Toxic and hazardous waste: they are hazardous substances that can be harmful to human health and natural environment directly or potentially, including abandoned household electronic products, such as batteries, fluorescent tubes, mercury thermometers, and abandoned paint barrels and buckets, expired cosmetics, expired medicine and so on. The recycled batteries including button batteries and lead-acid batteries that are used in watches and hearing aids for elder people, the abandoned and usual lithium batteries are not dangerous and they don’t need to be recycled.

(4) Other garbage: this includes food bags, storage bags, waste paper towels, discarded bottles and other cans with sticky foods.

4.2 Rational allocation of garbage classification facilities

In Beihang campus, the garbage classification barrels should be configured in accordance with uniform standards and technical requirements. Firstly, the color of trash bin must be unified: the color of bins for kitchen waste or compostable trash should be green, the color of bins for recyclable trash should be blue, and the color of bins for other trash should be gray. Secondly, the trash bin for toxic and hazardous garbage must be improved and added, and its color should be red. The volume of hazardous garbage bins can be smaller than others, and the classification frequency may be reduced depending on the amount of waste. Configuring garbage collection bucket must also be reasonable layout in order to be convenient for residents and school staff to do refuse delivery.

Garbage bins should be placed also in dormitory. If the space for garbage bin is limited in dormitory corridor, it will not be easy to put larger volume of garbage pails and the volume of garbage pails should be reduced. However, dormitory cleaners would require increasing the frequency of garbage collection and classification because of small volume of garbage pails, thereby it can prevent from incursion of mosquitoes and pollutions for corridor environment resulting from overflow of excessive garbage.

4.3 Establishment of impeccable garbage transport and treatment system

(1) For residential garbage transport process, the color of garbage transport vehicle should be consistent with the color of corresponding bins, which can be convenient for staff to do the garbage classification and transportation.

(2) Campus garbage treatment stations and Beihang logistics department can generalize the model for booking to recycle or going to the residents’ house to recycle garbage. This will save time, improve work efficiency, and can greatly improve resource utilization and garbage recyclable effectiveness.

(3) Using information technology to build video monitoring platform and realize visual management. Establishing digital monitoring in the school area with larger flow of people and places with garbage bin distribution to monitor the surrounding environment, and promptly correct the wrong garbage classification behavior. At the same time, installing video monitoring to realize the garbage disposal terminal orientation supervision and improve garbage treatment rate.

4.4 Creation of good awareness for garbage classification in public

Implementation of garbage classification, transportation and processing requires participation of all crew in campus of Beihang University. In additions, the Haidian district government departments should play a leading role in the activities for society and public awareness by performing with various media forms, such as newspaper column, campus education, theme activities, special movie, welfare animation, and volunteer activities. Taking advantages of newspapers, television, mobile media and network, knowledge concerning with garbage classification, transportation and processing can publish broadly, deeply, and persistently by printing and distribution of the popular science books to become popularize garbage classification knowledge and create incentives for public participation, mobilize public participation enthusiasm.

Recruiting some volunteers of campus through the Communist Youth League, various ways of different publicity for garbage classification can be carried out occasionally, and garbage classification awareness of the residents, teachers and students can be improved continuously.

Beihang University and Haoye Property Management Company will response the status of campus garbage classification and processing back to the campus community residents and students at regular intervals. Through the feedback of information, residents, teachers, and students will know the importance of classifying and recycling garbage for protection of campus environment and this will enhance the awareness of residents and teachers to protect campus environment [4].

In Western countries, environmental education started from the garbage at first. Garbage is the object that is closely related to our life. Accordingly, Beihang green campus waste recycling stations may become environmental education base for Beihang Elementary School, High School and College.

5. Conclusion

Garbage recycling and disposal is a major trend to help China become a "Beautiful China". In addition, it is also an important manifestation of green campus culture. The green campus waste treatment station established by Beihang University is used as the experimental base for solid waste treatment and disposal engineering course, which greatly improves students` ability to further understand the content of classroom teaching and apply it to practice. The experiment was designed to systematically grasp the general steps and process flow of waste resource treatment process and analyze the problems of campus waste classification system. Although there are still some problems in the campus waste separation, transportation and treatment system of Beihang University, these problems can be recognized and can be solved by proposing countermeasures. The relevant countermeasures derived from the results of this experiment can solve the problems in the waste disposal system, make up for its shortcomings, and maintain the eco-friendliness of the green campus. The further improved waste separation and disposal model of Beihang campus will be promoted and applied in Beijing and even in the campus of whole country.

References

[1] Wei Cui, Fei Li, Shaofei Kong. Circular economy and campus classified garbage recovery. Shanxi energy and energy saving, 2006,3:16-17.

[2] Huaqiang Sun, Defeng Yin, Lingyu Bu. Collection and utilization of campus life garbage. Cooperation of economy and technology. 2012:117-119.

[3] Yu Jiang, Jian Zhang, Bo Yan. Collection and transportation system construction of Chengdu city life garbage. Environmental sanitation engineering. 2012，20（6）:4-7.

[4] Espinosa R.M, Turpin S et al. Integral urban solid waste management program in a Mexican university. Waste Management, 2008, 28:527-532.