论文部分内容阅读
Abstract Taking the anaerobic digestion products of sludge as the object, through the analysis on the development of garden substrate market at home and abroad and the development status of horticultural products from the anaerobic digestion products, the direction for the utilization of the anaerobic digestion products of sludge was pointed out. Based on the demand of Chongqings garden market, this paper analyzed the potential utilization of sludge anaerobic digestion products in Chongqing, and briefly introduced the research status of landscaping utilization of sludge anaerobic digestion products in Chongqing, in order to provide reference for the industry.
Key words Sludge; Anaerobic digestion; Treatment product; Landscape application
Received: May 21, 2019Accepted: August 8, 2019
Supported by Project "Synergistic Anaerobic Digestion Technology of Municipal Sewage Sludge and Incineration Plant Landfill Leachate and Its Productivity Test" of Chongqing Water Asset Management Co. Ltd.
Sheng HE (1970-), male, P. R. China, senior engineer, devoted to research about environmental engineering.
*Corresponding author. Email: 2196341117@qq.com.
With the rapid development of the construction of sewage treatment facilities in China, the amount of sludge generated by sewage treatment plants is increasing. According to statistics, the sludge production of sewage plants in China has reached 43 million tons (calculated on the basis of a water content of 80%), and is expected to reach 60-90 million tons by the end of the "13th FiveYear Plan"［1-2］. The longterm sludge development strategy has led to the accumulation of sludge backlog becoming one of the major problems in Chinas environmental field. Anaerobic digestion is one of the mainstream technologies for sludge treatment in China［3-5］. The way out of the anaerobic digestion products of sludge from urban sewage treatment plants is a major problem faced by Chinas urban sewage treatment industry. With the acceleration of urbanization in China, the disposal of products produced by a large number of anaerobic digestion projects in urban sewage treatment plants will face increasing pressure. The resource utilization of sludge anaerobic digestion products is considered to be an appropriate disposal route for sludge because of its low cost and no entry into the human food chain［6］. The development of anaerobic digestion products of sludge special for landscaping can realize the diversification and functionalization of products for garden fertilization. The products are rich in organic matter and nutrients required for plant growth, and can be applied in landscaping after high temperature aerobic fermentation. Development of Garden Substrate Market at Home and Abroad
Development and research status of cultivation substrates at home and abroad
From the history of culture substrates at home and abroad, the research and production of substrates are mainly concentrated on crops. There is still no systematic research on culture substrates for garden plants, and the research on culture substrates for garden plants is still at the initial stage. For the research and development of substrate materials, there have been specialized substrate research and development institutions and production enterprises in countries with developed horticulture such the United States, Britain, Japan, etc.［8］. The substrates developed successively include peat, rock wool, vermiculite, perlite and other cultivation substrates, and mixed cultivation substrates of these substrates.
Chinas agroforestry development and cultivation substrate processing started late, while the use of natural substrates such as gravel and sand was earlier. Currently, coir dust, vermiculite and perlite have been industrially produced and widely used. Shandong, Henan and Hebei try to conduct industrialization exploitation of substrates using straw, rice husk, dregs and other materials. Hainan Province uses coir dust to cultivate crops and garden plants, and Guangxi and other places use bagasse for indepth research and development. Locally rich and cheap agricultural waste resources have been utilized according to local conditions. Jiangsu Academy of Agricultural Sciences and Nanjing Fiberglass Research & Design Institute Co., Ltd. cooperated in the research and development of agricultural rock wool, and achieved good results in the cultivation of vegetables and flowers, but they failed to keep on due to various reasons［7-9］.
Development status and research trends of garden cultivation substrates at home and abroad
Peat is commonly used as a light cultivation substrate for landscaping in China. However, since peat is a nonrenewable resource, mining in large quantities not only goes against the protection of resources, but also causes damage to the local ecological environment. When developing landscaping, China imports large amounts of peat, wood fiber and soil amendments from abroad, but these materials are expensive and cannot be applied in a large area. Therefore, it is necessary to develop cultivation substrates and fertilizers suitable for landscaping in China［7］. Aerobic fermentation products of organic waste such as sludge are often processed into light substrates or special fertilizers for flower cultivation, or used as soil conditioners. The substrates that have excellent physicochemical properties and good cultivation effect and can be used in large quantities are still traditional peat, perlite, vermiculite and rock wool, and other newly developed substrate materials are still insufficient. Some newly developed garden substrates have better effects in cultivation and seedling raising, but there are still problems of unstable quality and insufficient industrialization. In recent years, various local agricultural organic solid wastes such as mushroom residue, coir dust, straw, bar and straw have been used as raw materials to research and develop organic cultivation substrates［10］. These organic cultivation substrates have been applied to the cultivation and cultivation of garden plants, and have achieved certain effects. Some industrialized substrate products have been initially formed. The development of garden cultivation substrates that can be produced in large scale with good quality and low price is an important direction to promote the development of this industry.
Development Status of Garden Products from the Products of Sludge Anaerobic Digestion
Development of agricultural and forestry products from the products of sludge anaerobic digestion treatment
In recent years, some cities in China have begun to process sludge and anaerobic digestion products of sludge by hightemperature aerobic fermentation treatment into substrates, fertilizers, etc., which are mainly for agricultural use, and also have wide potential use. Qualified products are not only directly used as organic fertilizers, but also can be made into various types of special compound fertilizers, seedling substrates, etc., which can be applied to flowers, gardens, nurseries, etc.［11］. Some studies have shown that aerobic fermentation products of municipal sludge have high organic matter content, and complete longlasting nutrients including nitrogen, phosphorus, potassium and micronutrients. After being applied to the soil, their organic components can increase the buffer capacity of soil and increase the ability of soil to coordinate water, fertilizer, gas and heat, which plays an important role in increasing production, increasing income and sustainable agricultural development［12］. However, there are still obstacles other than technology in the agricultural use of aerobic fermentation products of sludge. Their use in landscaping does not suffer from great resistance currently, but compared with the agricultural market, the landscaping market has limited consumption capacity. It has been recognized that to improve the market competitiveness of sludge production products, it is necessary not only to make full use of the abundant resource advantages of municipal sludge according to local conditions, but also to carry out appropriate deep processing to effectively improve the reuse value and promotion of sludge treatment products. Development of landscaping substrate products from the products of sludge anaerobic digestion treatment
To prepare light and efficient roof greening cultivation substrates on the basis of combining the development of roof greening and sludge disposal problems by mixing urban sewage sludge with waste plant materials and adding beneficial microorganisms and other chemical and biological additives through biodegradation and fermentation is an important direction for the utilization of sludge in landscaping. This not only can solve the problem of lack of roof greening cultivation substrate production technology and promote the popularization of roof greening, but also can provide a new way for the disposal of sludge and waste plant materials to realize resource recycling. With the rapid rise of roof greening in China, localized research and development of localized roof greening substrates, especially those produced by industrial and agricultural wastes, have been valued［13］. Medium waste in the production of edible fungi, the waste bagasse in sugar industry, vinegar residue and reed residue are widely used in the production of roof greening cultivation substrates. At the T3 terminal of Chongqing Airport, plants including Sedum lineare Thunb. are cultivated in a roof greening soil prepared from sludge treatment products, peat, perlite and sand, and a good effect has been achieved. However, due to geographical differences, the resources available in different regions are not the same. The use of readymade products in other cities is bound to be limited by transportation costs and raw material sources, resulting in high prices of cultivation substrates and difficulty in popularizing roof greening. The localization of roof greening cultivation substrate preparation technology has become one of the technical bottlenecks for the development and popularization of roof greening in various cities.
In terms of the preparation technology of roof greening substrates, foreign technology is relatively mature. Under the premise of ensuring the waterretaining capacity of cultivation substrates, it is the development direction for foreign roof greening cultivation substrate preparation technology to reduce volume weight as much as possible. For example, roof greening in Japan uses artificial light soil synthesized from light aggregates such as vermiculite, perlite, cinder and peat; roof greening soils prepared in the United States and the United Kingdom use sand, humus and artificial lightweight materials; and Germany uses humus, peat, foamy scraps and organic fertilizers to synthesize roof greening soil［14］. The roof greening substrates in these countries are marketbased and have achieved significant economic, social and environmental benefits. Market Demand Analysis and Research Status of Sludge Anaerobic Digestion Products for Gardens in Chongqing
Quality of landscape soil in Chongqing
The main urban area of Chongqing is located in the parallel ridgevalley region of the fold belt in the eastern part of Sichuan Basin. The urban soil is dominated by neutral and calcareous purple soil developed from the weathered materials of purple sandearth rock［15］. As a special kind of urban soil, gardening soil has different characteristics from general urban soil or farmland soil. It mainly comes from foreign soil, and a large part is foreign soil or additives. The urban construction in the main urban area of Chongqing makes the garden soil complex and the soil layers disordered. The topsoil is often removed or buried by the subsoil, and the soil layer is often mixed with the bottom layer of dead soil or raw soil, as well as a large amount of gravel and construction waste. In addition, the strong influence of human activities changes the physical and chemical properties of the soil, degrades its structure, and leads to nutrient deficiency, thereby affecting the ecological greening effect of garden plants.
There are three main problems in the garden soil of Chongqings main city: slightly alkaline, low nutrient contents and poor physical properties. The organic matter content of street soil in Chongqing is between 1.6 and 45 g/kg, with an average of 14.4 g/kg, and 55% of the soil has a low soil organic matter content. The available nitrogen (alkalihydrolyzable nitrogen) content is between 9.5 and 551 mg/kg, with an average of 63.1 mg/kg, and 41% of the soil shows a low available nitrogen content. The available phosphorus content is in the range of 0.857-94.7 mg/kg, overall at a deficient level, with an average of 14.9 mg/kg, and 61% of the soil exhibited a low available phosphorus content. The average value of rapidly available potassium is 137 mg/kg, and the content is medium. Such levels of nutrients tend to cause slow recovery and growth retardation. In addition, the replenishment of nutrients in garden greenbelts cannot balance soil fertility, and the soil fertility is gradually decreasing, which restricts the improvement of urban green space productivity. With the rapid development of landscaping, improving the maintenance quality and level of garden has become an urgent task for urban landscaping. Of all the tasks, soil fertilization is an important one in the landscaping maintenance work, and it is also a work with high technical requirements and difficult operation. Research status of garden utilization of anaerobicallydigested sludge in Chongqing City
In 2012, Chongqing supported the construction of a sludge disposal base for Chongqing, which was designed with a daily treatment capacity of sludge (water content of 80%) of 200 t, which enabled the garden utilization of sludge in Chongqing to enter the stage of engineering demonstration. However, the aerobic fermentation treatment technology that the project relies on is based on dewatered sludge, not the products produced by anaerobic digestion of sludge. There are various kinds of garden plants and rich types of garden green space, while the single sludge anaerobic digestion products cannot meet the diversified needs of the garden market. In recent years, Chongqing Water Asset Management Co., Ltd. and Chongqing Landscape and Gardening Research Institute have used sludge anaerobic digestion products as raw materials to study the aerobic fermentation technology of sludge anaerobic digestion products and garden product production technology and to research and develop series landscaping special fertilizers according to the quality characteristics of Chongqing garden soil and the growth characteristics of different garden plants. Garden application tests were carried out on the products, forming a comprehensive utilization technology of sludge anaerobic digestion products, which comprehensively improves the technical level of garden resource industrialization of sludge anaerobic digestion products. Talent support and technical support can be provided for the utilization of garden anaerobic digestion products in Chongqing, and the utilization of garden anaerobic digestion products is developing towards a refined and scientific direction. The outlet for the anaerobic digestion products of sludge is greatly expanded, which ensures the stable operation of sludge anaerobic digestion projects in turn.
Sheng HE et al. Analysis on Present Situation of Anaerobic Digestion Products of Sludge in Landscaping Application and Market Demand in Chongqing
Conclusion
Sludge anaerobic digestion is one of the commonly used methods for sludge reduction and stabilization, by which the organic matter in sludge is decomposed by anaerobic reaction, and a large amount of high calorific value biogas can be used as energy source［1-3］. Since the application of sludge in gardens is separated from the food chain, it does not pose a direct threat to human health. Together with the support of the national economic policy, the anaerobic digestion products of sludge are more competitive in the market and can be widely used in urban landscaping. The use of sludge anaerobic digestion products for garden utilization is an important direction for its resource utilization. According to the analysis of the garden substrates and soil market in Chongqing, Chongqings garden market has a large demand for solid digestion products produced by anaerobic digestion of sludge. The research and exploration of the landscaping utilization of sludge anaerobic digestion products by the water and garden departments of Chongqing provides an important reference for the comprehensive utilization of sludge anaerobic digestion products in China. References
［1］ WANG T, WANG XJ. Anaerobic digestion technology status of sludge disposal and concerned problems［J］. China Environmental Protection Industry, 2013(5): 49-54. (in Chinese)
［2］ WU J, JIANG J, ZHOU HM, et al. Current operation status of sludge anaerobic digestion system in municipal wastewater treatment plants in China［J］. China Water and Wastewater, 2008, 24(22): 21-24. (in Chinese)
［3］ CHEN J, YANG Q. Stateoftheart and development trend of biosolid advanced anaerobic digestion technologies［J］. China Water and Wastewater, 2016(6):19-23. (in Chinese)
［4］ LI L. Application status and trend on anaerobic digestion technology development of sludge［J］. China Environmental Protection Industry, 2013(8): 57-60. (in Chinese)
［5］ CAO XQ, CHEN AN, GAN YP, et al. New development of anaerobic digestion technology of sewage sludge［J］. Environmental Engineering, 2008, 26(S1): 215-219, 223. (in Chinese)
［6］ YUE J, MA YH, WANG Q, et al. Application of urban living sludge in garden and ecological risk assessment［J］. Northern Horticulture, 2018(7): 98-104. (in Chinese)
［7］ WANG LH, YANG QS. Research progress on new horticultural cultivation substrates［J］. Journal of Henan Agricultural Sciences, 2015, 44(3): 9-13. (in Chinese)
［8］ GUO SR.Research progress, current exploitations and developing trends of solid cultivation medium［J］. Transactions of the Chinese Society of Agricultural Engineering, 2005(S2): 1-4. (in Chinese)
［9］ TIAN JL, WANG YH. Current situations and prospects of researches on soillessculture substrates［J］. Acta Agriculturae Shanghai, 2000(04): Acta Agriculturae Shanghai, 87-92. (in Chinese)
［10］ MAO Y, ZHANG WD. Advances in research on soilless culture substrates［J］. Agriculture and Technology, 2004(3): 83-88. (in Chinese)
［11］ WANG S, BAO JG, LIU CL. Study on characteristics of urban sludge and analysis of its prospects for landscaping utilization［J］. Environmental Science & Technology, 2010, 33(S1): 238-241, 247. (in Chinese)
［12］ LI GB, DU X. Use and prospect of municipal sewage sludge in forestland and green areas［J］. Environmental Protection, 2001(12): 37-38. (in Chinese)
［13］ SHI ZJ, LEI JL, TAN YF, et al. Study on light roof greening cultivation substrate［J］. Civil Engineering & Architecture, 2005, 2(2): 52-54. (in Chinese)
［14］ LI QS. Growing media selection for green roof［J］. Journal of Anhui Agricultural Sciences, 2005, 33(1): 84-85. (in Chinese)
［15］ WANG M. The formative characteristics of soil resources and its distribution principle in Chongqing［J］. Journal of Chongqing College of Education, 2002(6): 60-63. (in Chinese)
Key words Sludge; Anaerobic digestion; Treatment product; Landscape application
Received: May 21, 2019Accepted: August 8, 2019
Supported by Project "Synergistic Anaerobic Digestion Technology of Municipal Sewage Sludge and Incineration Plant Landfill Leachate and Its Productivity Test" of Chongqing Water Asset Management Co. Ltd.
Sheng HE (1970-), male, P. R. China, senior engineer, devoted to research about environmental engineering.
*Corresponding author. Email: 2196341117@qq.com.
With the rapid development of the construction of sewage treatment facilities in China, the amount of sludge generated by sewage treatment plants is increasing. According to statistics, the sludge production of sewage plants in China has reached 43 million tons (calculated on the basis of a water content of 80%), and is expected to reach 60-90 million tons by the end of the "13th FiveYear Plan"［1-2］. The longterm sludge development strategy has led to the accumulation of sludge backlog becoming one of the major problems in Chinas environmental field. Anaerobic digestion is one of the mainstream technologies for sludge treatment in China［3-5］. The way out of the anaerobic digestion products of sludge from urban sewage treatment plants is a major problem faced by Chinas urban sewage treatment industry. With the acceleration of urbanization in China, the disposal of products produced by a large number of anaerobic digestion projects in urban sewage treatment plants will face increasing pressure. The resource utilization of sludge anaerobic digestion products is considered to be an appropriate disposal route for sludge because of its low cost and no entry into the human food chain［6］. The development of anaerobic digestion products of sludge special for landscaping can realize the diversification and functionalization of products for garden fertilization. The products are rich in organic matter and nutrients required for plant growth, and can be applied in landscaping after high temperature aerobic fermentation. Development of Garden Substrate Market at Home and Abroad
Development and research status of cultivation substrates at home and abroad
From the history of culture substrates at home and abroad, the research and production of substrates are mainly concentrated on crops. There is still no systematic research on culture substrates for garden plants, and the research on culture substrates for garden plants is still at the initial stage. For the research and development of substrate materials, there have been specialized substrate research and development institutions and production enterprises in countries with developed horticulture such the United States, Britain, Japan, etc.［8］. The substrates developed successively include peat, rock wool, vermiculite, perlite and other cultivation substrates, and mixed cultivation substrates of these substrates.
Chinas agroforestry development and cultivation substrate processing started late, while the use of natural substrates such as gravel and sand was earlier. Currently, coir dust, vermiculite and perlite have been industrially produced and widely used. Shandong, Henan and Hebei try to conduct industrialization exploitation of substrates using straw, rice husk, dregs and other materials. Hainan Province uses coir dust to cultivate crops and garden plants, and Guangxi and other places use bagasse for indepth research and development. Locally rich and cheap agricultural waste resources have been utilized according to local conditions. Jiangsu Academy of Agricultural Sciences and Nanjing Fiberglass Research & Design Institute Co., Ltd. cooperated in the research and development of agricultural rock wool, and achieved good results in the cultivation of vegetables and flowers, but they failed to keep on due to various reasons［7-9］.
Development status and research trends of garden cultivation substrates at home and abroad
Peat is commonly used as a light cultivation substrate for landscaping in China. However, since peat is a nonrenewable resource, mining in large quantities not only goes against the protection of resources, but also causes damage to the local ecological environment. When developing landscaping, China imports large amounts of peat, wood fiber and soil amendments from abroad, but these materials are expensive and cannot be applied in a large area. Therefore, it is necessary to develop cultivation substrates and fertilizers suitable for landscaping in China［7］. Aerobic fermentation products of organic waste such as sludge are often processed into light substrates or special fertilizers for flower cultivation, or used as soil conditioners. The substrates that have excellent physicochemical properties and good cultivation effect and can be used in large quantities are still traditional peat, perlite, vermiculite and rock wool, and other newly developed substrate materials are still insufficient. Some newly developed garden substrates have better effects in cultivation and seedling raising, but there are still problems of unstable quality and insufficient industrialization. In recent years, various local agricultural organic solid wastes such as mushroom residue, coir dust, straw, bar and straw have been used as raw materials to research and develop organic cultivation substrates［10］. These organic cultivation substrates have been applied to the cultivation and cultivation of garden plants, and have achieved certain effects. Some industrialized substrate products have been initially formed. The development of garden cultivation substrates that can be produced in large scale with good quality and low price is an important direction to promote the development of this industry.
Development Status of Garden Products from the Products of Sludge Anaerobic Digestion
Development of agricultural and forestry products from the products of sludge anaerobic digestion treatment
In recent years, some cities in China have begun to process sludge and anaerobic digestion products of sludge by hightemperature aerobic fermentation treatment into substrates, fertilizers, etc., which are mainly for agricultural use, and also have wide potential use. Qualified products are not only directly used as organic fertilizers, but also can be made into various types of special compound fertilizers, seedling substrates, etc., which can be applied to flowers, gardens, nurseries, etc.［11］. Some studies have shown that aerobic fermentation products of municipal sludge have high organic matter content, and complete longlasting nutrients including nitrogen, phosphorus, potassium and micronutrients. After being applied to the soil, their organic components can increase the buffer capacity of soil and increase the ability of soil to coordinate water, fertilizer, gas and heat, which plays an important role in increasing production, increasing income and sustainable agricultural development［12］. However, there are still obstacles other than technology in the agricultural use of aerobic fermentation products of sludge. Their use in landscaping does not suffer from great resistance currently, but compared with the agricultural market, the landscaping market has limited consumption capacity. It has been recognized that to improve the market competitiveness of sludge production products, it is necessary not only to make full use of the abundant resource advantages of municipal sludge according to local conditions, but also to carry out appropriate deep processing to effectively improve the reuse value and promotion of sludge treatment products. Development of landscaping substrate products from the products of sludge anaerobic digestion treatment
To prepare light and efficient roof greening cultivation substrates on the basis of combining the development of roof greening and sludge disposal problems by mixing urban sewage sludge with waste plant materials and adding beneficial microorganisms and other chemical and biological additives through biodegradation and fermentation is an important direction for the utilization of sludge in landscaping. This not only can solve the problem of lack of roof greening cultivation substrate production technology and promote the popularization of roof greening, but also can provide a new way for the disposal of sludge and waste plant materials to realize resource recycling. With the rapid rise of roof greening in China, localized research and development of localized roof greening substrates, especially those produced by industrial and agricultural wastes, have been valued［13］. Medium waste in the production of edible fungi, the waste bagasse in sugar industry, vinegar residue and reed residue are widely used in the production of roof greening cultivation substrates. At the T3 terminal of Chongqing Airport, plants including Sedum lineare Thunb. are cultivated in a roof greening soil prepared from sludge treatment products, peat, perlite and sand, and a good effect has been achieved. However, due to geographical differences, the resources available in different regions are not the same. The use of readymade products in other cities is bound to be limited by transportation costs and raw material sources, resulting in high prices of cultivation substrates and difficulty in popularizing roof greening. The localization of roof greening cultivation substrate preparation technology has become one of the technical bottlenecks for the development and popularization of roof greening in various cities.
In terms of the preparation technology of roof greening substrates, foreign technology is relatively mature. Under the premise of ensuring the waterretaining capacity of cultivation substrates, it is the development direction for foreign roof greening cultivation substrate preparation technology to reduce volume weight as much as possible. For example, roof greening in Japan uses artificial light soil synthesized from light aggregates such as vermiculite, perlite, cinder and peat; roof greening soils prepared in the United States and the United Kingdom use sand, humus and artificial lightweight materials; and Germany uses humus, peat, foamy scraps and organic fertilizers to synthesize roof greening soil［14］. The roof greening substrates in these countries are marketbased and have achieved significant economic, social and environmental benefits. Market Demand Analysis and Research Status of Sludge Anaerobic Digestion Products for Gardens in Chongqing
Quality of landscape soil in Chongqing
The main urban area of Chongqing is located in the parallel ridgevalley region of the fold belt in the eastern part of Sichuan Basin. The urban soil is dominated by neutral and calcareous purple soil developed from the weathered materials of purple sandearth rock［15］. As a special kind of urban soil, gardening soil has different characteristics from general urban soil or farmland soil. It mainly comes from foreign soil, and a large part is foreign soil or additives. The urban construction in the main urban area of Chongqing makes the garden soil complex and the soil layers disordered. The topsoil is often removed or buried by the subsoil, and the soil layer is often mixed with the bottom layer of dead soil or raw soil, as well as a large amount of gravel and construction waste. In addition, the strong influence of human activities changes the physical and chemical properties of the soil, degrades its structure, and leads to nutrient deficiency, thereby affecting the ecological greening effect of garden plants.
There are three main problems in the garden soil of Chongqings main city: slightly alkaline, low nutrient contents and poor physical properties. The organic matter content of street soil in Chongqing is between 1.6 and 45 g/kg, with an average of 14.4 g/kg, and 55% of the soil has a low soil organic matter content. The available nitrogen (alkalihydrolyzable nitrogen) content is between 9.5 and 551 mg/kg, with an average of 63.1 mg/kg, and 41% of the soil shows a low available nitrogen content. The available phosphorus content is in the range of 0.857-94.7 mg/kg, overall at a deficient level, with an average of 14.9 mg/kg, and 61% of the soil exhibited a low available phosphorus content. The average value of rapidly available potassium is 137 mg/kg, and the content is medium. Such levels of nutrients tend to cause slow recovery and growth retardation. In addition, the replenishment of nutrients in garden greenbelts cannot balance soil fertility, and the soil fertility is gradually decreasing, which restricts the improvement of urban green space productivity. With the rapid development of landscaping, improving the maintenance quality and level of garden has become an urgent task for urban landscaping. Of all the tasks, soil fertilization is an important one in the landscaping maintenance work, and it is also a work with high technical requirements and difficult operation. Research status of garden utilization of anaerobicallydigested sludge in Chongqing City
In 2012, Chongqing supported the construction of a sludge disposal base for Chongqing, which was designed with a daily treatment capacity of sludge (water content of 80%) of 200 t, which enabled the garden utilization of sludge in Chongqing to enter the stage of engineering demonstration. However, the aerobic fermentation treatment technology that the project relies on is based on dewatered sludge, not the products produced by anaerobic digestion of sludge. There are various kinds of garden plants and rich types of garden green space, while the single sludge anaerobic digestion products cannot meet the diversified needs of the garden market. In recent years, Chongqing Water Asset Management Co., Ltd. and Chongqing Landscape and Gardening Research Institute have used sludge anaerobic digestion products as raw materials to study the aerobic fermentation technology of sludge anaerobic digestion products and garden product production technology and to research and develop series landscaping special fertilizers according to the quality characteristics of Chongqing garden soil and the growth characteristics of different garden plants. Garden application tests were carried out on the products, forming a comprehensive utilization technology of sludge anaerobic digestion products, which comprehensively improves the technical level of garden resource industrialization of sludge anaerobic digestion products. Talent support and technical support can be provided for the utilization of garden anaerobic digestion products in Chongqing, and the utilization of garden anaerobic digestion products is developing towards a refined and scientific direction. The outlet for the anaerobic digestion products of sludge is greatly expanded, which ensures the stable operation of sludge anaerobic digestion projects in turn.
Sheng HE et al. Analysis on Present Situation of Anaerobic Digestion Products of Sludge in Landscaping Application and Market Demand in Chongqing
Conclusion
Sludge anaerobic digestion is one of the commonly used methods for sludge reduction and stabilization, by which the organic matter in sludge is decomposed by anaerobic reaction, and a large amount of high calorific value biogas can be used as energy source［1-3］. Since the application of sludge in gardens is separated from the food chain, it does not pose a direct threat to human health. Together with the support of the national economic policy, the anaerobic digestion products of sludge are more competitive in the market and can be widely used in urban landscaping. The use of sludge anaerobic digestion products for garden utilization is an important direction for its resource utilization. According to the analysis of the garden substrates and soil market in Chongqing, Chongqings garden market has a large demand for solid digestion products produced by anaerobic digestion of sludge. The research and exploration of the landscaping utilization of sludge anaerobic digestion products by the water and garden departments of Chongqing provides an important reference for the comprehensive utilization of sludge anaerobic digestion products in China. References
［1］ WANG T, WANG XJ. Anaerobic digestion technology status of sludge disposal and concerned problems［J］. China Environmental Protection Industry, 2013(5): 49-54. (in Chinese)
［2］ WU J, JIANG J, ZHOU HM, et al. Current operation status of sludge anaerobic digestion system in municipal wastewater treatment plants in China［J］. China Water and Wastewater, 2008, 24(22): 21-24. (in Chinese)
［3］ CHEN J, YANG Q. Stateoftheart and development trend of biosolid advanced anaerobic digestion technologies［J］. China Water and Wastewater, 2016(6):19-23. (in Chinese)
［4］ LI L. Application status and trend on anaerobic digestion technology development of sludge［J］. China Environmental Protection Industry, 2013(8): 57-60. (in Chinese)
［5］ CAO XQ, CHEN AN, GAN YP, et al. New development of anaerobic digestion technology of sewage sludge［J］. Environmental Engineering, 2008, 26(S1): 215-219, 223. (in Chinese)
［6］ YUE J, MA YH, WANG Q, et al. Application of urban living sludge in garden and ecological risk assessment［J］. Northern Horticulture, 2018(7): 98-104. (in Chinese)
［7］ WANG LH, YANG QS. Research progress on new horticultural cultivation substrates［J］. Journal of Henan Agricultural Sciences, 2015, 44(3): 9-13. (in Chinese)
［8］ GUO SR.Research progress, current exploitations and developing trends of solid cultivation medium［J］. Transactions of the Chinese Society of Agricultural Engineering, 2005(S2): 1-4. (in Chinese)
［9］ TIAN JL, WANG YH. Current situations and prospects of researches on soillessculture substrates［J］. Acta Agriculturae Shanghai, 2000(04): Acta Agriculturae Shanghai, 87-92. (in Chinese)
［10］ MAO Y, ZHANG WD. Advances in research on soilless culture substrates［J］. Agriculture and Technology, 2004(3): 83-88. (in Chinese)
［11］ WANG S, BAO JG, LIU CL. Study on characteristics of urban sludge and analysis of its prospects for landscaping utilization［J］. Environmental Science & Technology, 2010, 33(S1): 238-241, 247. (in Chinese)
［12］ LI GB, DU X. Use and prospect of municipal sewage sludge in forestland and green areas［J］. Environmental Protection, 2001(12): 37-38. (in Chinese)
［13］ SHI ZJ, LEI JL, TAN YF, et al. Study on light roof greening cultivation substrate［J］. Civil Engineering & Architecture, 2005, 2(2): 52-54. (in Chinese)
［14］ LI QS. Growing media selection for green roof［J］. Journal of Anhui Agricultural Sciences, 2005, 33(1): 84-85. (in Chinese)
［15］ WANG M. The formative characteristics of soil resources and its distribution principle in Chongqing［J］. Journal of Chongqing College of Education, 2002(6): 60-63. (in Chinese)