Songming Waste fruit and vegetable resource comprehensive utilization project in Yunnan

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Songming County, part of Kunming city in Yunnan Province, produces nearly 1,500 tons of discarded vegetable leaves every day, with a peak of more than 3,000 tons. Only a small part of these fruit and vegetable wastes were taken to landfill sites in counties and townships by professional cleaners and transporters, and most of them were left by farmers on the roadside, in ditches and in fields. The leachate produced by waste vegetable leaf garbage landfill and roadside dumping has caused direct pollution of surface water and groundwater, threatening the water quality of Niulan River.

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The production of fruit and vegetable waste organic waste disposal project is by "Shanghai xing energy environmental protection technology co., LTD." to provide technical support of large-scale biogas project, the construction since June 2017 to June 2018 debugging is completed, the project with methane as a link to a project, the construction of environment and resource recycling energy organically combined into an organic whole, implementation of agricultural waste recycling use. After the completion of the project, it can not only reduce the emission of pollutants, but also create certain economic benefits and form a pollution-free sustainable development of ecological recycling economy system.

The anaerobic facilities in this project cover an area of about 8 mu, and there are 4 single fermentation tanks of 3300 cubic meters, with medium temperature fermentation at 35℃. The semi-dry anaerobic fermentation process was used to treat the vegetable waste of 1200t per day, and the daily output of methane was about 40000 cubic meters. The whole plant includes feeding system, pretreatment system, anaerobic fermentation system, dehydration system, methane purification - storage system, sewage treatment system.

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Process selection

However, due to the large scale of treatment, traditional wet process will produce large amount of biogas slurry, which is difficult to be absorbed, especially in the non-fertilizing season in winter. Due to large treatment scale, large scale of anaerobic fermentation system, large investment and large floor space; In order to maximize the benefit after the completion of the project, increase the project biogas production, reduce the discharge volume of biogas slurry, and avoid the problems of scum and sand settling caused by the wet fermentation process. Therefore, it is recommended to adopt the dry anaerobic fermentation technology as the core technology of the biogas project.

Low solid anaerobic digestion dry anaerobic digestion

Fermentation concentration is 5%-10%, 10%-15%

Hydraulic retention time 15 ~ 20 days 20 ~ 30 days

Pool capacity and gas production rate 0.8 ~ 1.2 m3 / m3. D 2.0 ~ 2.5 m3 / m3. D

The thermal biogas production capacity is higher, about 20% ~ 30% biogas production capacity is lower, about 10 ~ 15%

There is little or no need for water

Biogas slurry amounts to little or no base

The possibility of fermenter operation in tank production scum and precipitation is threatened

Stable operation of fermenter. Basically, no scum and no sediment will be produced in the tank,

Thus ensuring the stable operation of fermenter.

 

The process flow

After the vegetable waste is transported to the plant, it is first put into the pretreatment system for crushing and dehydration. Vegetable pressing liquid enters the sewage treatment system, and is discharged after purification to the standard. The vegetable dregs enter the fermenter system and produce biogas by anaerobic fermentation. The biogas enters the whole plant biogas utilization system. The slurry after anaerobic fermentation enters into biogas slurry dehydration system for solid liquid separation, producing biogas slurry and biogas slurry. Dehydrated biogas residue is used to produce organic manure by composting. Biogas slurry is used as liquid fertilizer in the surrounding planting area.

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Project summary

1. The solid residue after anaerobic fermentation of this project becomes excellent organic matter, which can be provided to flower enterprises in the agricultural park. Flower enterprises no longer need to buy organic matter from abroad, and at the same time help enterprises to save the treatment cost of waste fruits and vegetables.

2. In the whole production process, waste from waste fruits and vegetables can be made comprehensive utilization of resources, which is more energy saving and environmental protection, and no secondary pollution will be generated in the whole process. Meanwhile, the circular economic model of planting industry - biogas - organic fertilizer - organic planting agriculture has also been formed.