-Beijing Example
Zhang Yi'an, Gao Ding, Chen Tongbin*, Zheng Main, Li Yanxia
Institute of Science and Resources, Academia Sinica, Environmental Remediation, Beijing, China, 100101
Abstract: Beijing Example: Estimation of the same tariffs and transportation distances for landfill, incineration, and composting. The basic discussion on the various treatment and disposal cases and the prospect of Beijing sludge treatment and disposal road sludge landfill regular main treatment and disposal style proportion gradually decline; composting economic more line treatment and disposal style is suitable for the force to promote; with the improvement of the economic strength and technical level incineration is suitable for other special points with the analysis of the impact of government subsidies on the effectiveness of sludge treatment and disposal
Keywords: Municipal sludge; treatment and disposal of this; landfill; incineration; composting
Figure number: X703 Literature identification code: A Article number: 1672-2175 (2006) 02-0234-05
Municipal sludge sewage treatment by-products of water content of 97% calculated volume of treated sewage accounted for 0.3% to 0.5%[1] depth treatment of the sludge production increased by 50% ~ 100% at present I discharged every dry sludge, and the volume of the sludge production increased by 50% ~ 100%. 100% At present, I discharged every dry sludge about 1.3 × 106 t and about 10% rate of increase
Beijing's entire regional planning sewage discharge volume of 330 × 104 m3 / d of its 2003 urban sewage discharge volume of about 230 × 104 m3 / d [2] planning the construction of 14 wastewater treatment plants in 2015 sewage treatment capacity is expected to be more than 320 × 104 m3 / d treatment rate of over 90% 2008 Beijing added 9 new water treatment plant depth treatment capacity from the current 1 × 104 m3 / d to increase 47.6 × 104 m3 / d session per output moisture content of 80% of municipal sludge over 80 × 104 m3 Beijing sewage treatment plant - Gaobeidian sewage treatment plant sludge outbound transportation costs accounted for the entire plant operating costs1 /3[3]
Municipal sludge production has caused more serious pollution and urban sewage treatment industry bottlenecks sludge treatment and disposal rate is low, and its non-important original investment and operation of the face of the limitation of the economic analysis of the case of the same sludge treatment and disposal of the case led to the same unit designers to choose the case of the existence of a more blind This paper Beijing example of several typical urban sludge treatment and disposal of the economic analysis of the case of the choice of municipal sludge treatment and disposal technology to provide a reference basis for the city sludge treatment and disposal of technology. Provide reference basis
1 Municipal sludge treatment and disposal cost estimation
1.1 Estimation
1 t of dry sludge (DS) calculation benchmark comprehensive cost = operation cost + equipment discount cost operation cost is currently more familiar treatment and disposal style for estimation
Beijing sludge mechanical dewatering efficiency through about 80% of each case costs estimate involves or includes incineration, transportation, landfill and other 3 processes; equipment discount cost is taken as 15 percent of the cost of the equipment. Process; equipment discount this take 15 a use limit depreciation 7% social interest rate 10% that is 17% discount equipment work 8000 h count equipment discount = equipment price × index × 0.17/8000
1.2 Estimation details
(1) unit of this
Landfill: garbage Wei landfill cost of about 60 ~ 70 ￥ / t sludge landfill in accordance with the compaction of garbage: soil: sludge volume to weight ratio of 0.8 ￥ / t. Sludge volume to weight ratio of 0.8:1:1 sludge landfill this 48~56 ￥ / t to take 52 ￥ / t
Drying: drying energy consumption and dehydration than the gas heating efficiency of 85%, the boiler thermal efficiency of 70%, the process of heat loss of 5% of the water evaporation energy consumption of 150 (kW?h)/t per removal of 1 t of water investment of 180 × 104 ￥ equipment [4]
Incineration: the current use of fluidized bed technology Incineration of 1 t of dry sludge per h equipment this 528 × 104 ￥ sludge by 60% reduction in dry mass incineration operating costs 24 ￥ / t flue gas treatment consumption of NaOH amount of about 37 kg / t discount of about 128 ￥ / t [5]
Electricity prices: Beijing industrial tariffs in the peak period, the flat section of the area, the trough period of 0.278, 0.488, 0.725 ￥ / (kW?h) according to the same Subsidized case tariffs set 0.30, 0.60 ￥ / (kW?h)
Freight: Beijing transportation prices 0.45 ~ 0.65 ￥ / (t?km) between the sludge special solid waste need special box trucks to deliver the price at the high end in addition to the recent trend of rising transport prices freight take 0.65 ￥ / (t?km)
Outside the drying and incineration of the equipment to add 30% of the cost! Material consumption labor management fees and civil construction support costs
(2) sludge moisture content
Sludge organic water content is high landfill storage series of problems before the main off-soil hydraulic properties moisture content is higher than 68% need to be mixed into the soil according to the ratio of m (soil): m (sludge) = 0.4 ~ 0.6 [6-8] moisture content to reduce the sludge properties of the existence of sudden changes in landfill dewatering target set at 80%, 30%
Moisture content sludge incineration treatment of key elements of high organic matter content, low moisture content is conducive to maintaining spontaneous combustion to reduce the sludge moisture content to reduce the sludge incineration equipment and treatment costs is critical to reduce the general sludge moisture content down to the ratio of volatile matter content than the 3.5 shape of the spontaneous combustion [9] Beijing City sludge organic matter content of 45% of sludge so that sludge to maintain the spontaneous combustion of the incineration of the water content should be less than 61.2% of the N. W. Zhu summarized several kinds of sludge outside the thermal drying technology sludge drying to 10% moisture content [10] sludge incineration comprehensive cost changes with the degree of drying state the higher the degree of drying drying energy consumption rises incineration equipment and operating costs with the decline of simplification for the sake of simplicity in this paper, sludge to maintain heat balance combustion estimation of the premise and then high water to add heavy oil this estimation of sludge incineration drying target is set at: 60% 10%
Table 1 Beijing Landfill Overview [11] and the proximity to the wastewater treatment plant
Table 1 Description of Beijing Landfill Overview [11] and the proximity to the wastewater treatment plant
Table 1 Description of landfill sites and wastewater treatment plants
Landfill site Landfill site location Treatment scale/(t?d-1) Expected closure between Near wastewater treatment plant Near straight-line distance/km 1)
Beijing Shenshu Tongxian Quixiang 980 2006 Gaobeidian 20
Anding Anding Township, Xing District 700 2006 Hongmen 36
Liu Tun Yongfengtun Township, Haidian District 1500 2017 Qinghe 15
Gao'antun Louzizhuang Township, Chaoyang District 1000 2018 Gaobeidian 15
Asuwei Tangshan Township, Changping District 2000 2012 Qinghe and Beihe 40
Jiaojiapo Yongding Township, Mengou District 600 2011 Lugouqiao 15
1) Nearby Data Author's Actual Measurements
Summary of sludge treatment and disposal: composting don't dry to 80% water, 30% landfill drying to 60% water, 10% incineration
1.3 Landfill Cost
Landfill cost=energy cost+transportation cost+equipment discount price Landfill cost + equipment discount cost
Energy cost = [1/(1-η0)-1/(1-ηe)]×150×α×Pele
Transportation cost = 0.65×L /(1-ηe)
Landfill cost = βPf /(1- ηe)
Equipment discount = [1/(1-η0)-1/(1-ηe)]×180×α× 0.17×104/8000
The η0, ηe don't deal with the beginning and end of the disposal of the moisture content; Pele electricity price of ￥ / (kW?h); L transportation distance km; α civil and industrial supporting cost index 1.3; β volume coefficient water content ≥ 68% 1.4 ~ 1.6 between take 1.5 water content <68% take 1; Pf landfill landfill price 40 ~ 60 ￥ / t to take 52 ￥ / t
Sludge landfill transportation distance: Beijing City, the current capacity of landfill is sufficient to meet the demand for garbage disposal even if the planning of landfill to build a landfill capacity of surplus limited to the sludge The landfill needs to find a new landfill with the development of the city and the landfill quality conditions require that the transportation distance is farther and farther with reference to Table 1 sludge
The landfill transportation distance of 40 km is estimated for today's landfill, respectively, 50, 100 km for the recent and long-term landfill transportation distance
1.4 Composting costs and revenues
City sludge composted by the composting of the harmful treatment of the soil is commonly used in the international community. Treatment and disposal type forced ventilation static stack composting treatment sludge composting mainstream technology and its treatment of this sludge with the initial moisture content, scale of treatment, composting plant and sewage treatment plant between the distance and the original production of equipment and other factors related to the composting plant is appropriate to build around the sewage treatment plant transportation costs 0 composting this mainly by the blower, drying, sieve energy consumption conditioning agent and equipment depreciation group of the current composting products market price of 350 ~ 500 ￥ / t minus 15% of the moisture content. The water content of 500￥/t DS
Using the CTB composting self-control system [12,13] to carry out forced ventilation static stack composting Luohe City, Henan Province, urban sludge composting plant application results show that the sludge moisture content of more than 80% of the blower energy consumption of 40 to 60 (kW?h)/t DS between the 60 (kW?h)/t DSCTB conditioning agent price of 300 ￥/t loss of the rate of the general 5% [14] After 10~14 d composting sludge dry matter reduction 30% water content 45% using thermal drying technology drying to 15% water content dewatering load 0.45 t/t DS; conditioning agent drying before the sieve from the drying need to sieve energy consumption; sieve load ***9.3 t/t DS sieve capacity 1 t/h power 3 kW whole energy consumption 95 (kW?h)/t DS considering unknown energy consumption take 100 (kW?) /t DS
Equipment discount: treatment of dry sludge capacity 0.3 × 104 t/a sludge composting plant equipment investment of about 7 million ￥ equipment discount 182 ￥ / t DS (including accounted for the cost of) to take 200 ￥ / t DS
1.5 incineration of this
Taking into account the incineration of emissions and other issues such as the incineration of waste gas transported out of the 30 km incineration of 30 km; incineration of the reduction in the amount of dry matter 60% of the burnt residues need to be transported to the landfill landfill transportation distance of 50 km reference to Table 3 know that drying to 10% incineration cost is lower than drying to 60% the higher the degree of drying the incineration plant occupies the more the incineration of the area of the pre-incineration of drying to 10% should be
1.6 drying of the agricultural cost
without stabilization of the sludge treatment of the existence of the danger of the safety of the application of the sludge to take into account the drying and stabilization of the effectiveness of the worse safety limit and then estimate
2 Discussion and analysis
2.1 Treatment cost and economic benefits
Table 2 Comparison of the estimated cost and benefit of sewage sludge treated and/or disposed by different ways
Table 2 Comparison of the estimated cost and benefit of sewage sludge treated and/or disposed by different ways
Table 2 Comparison of the estimated cost and benefit of sewage sludge treated and/or disposed by different ways
Filling and burying
Drying Transportation Landfilling Comprehensive cost/$
Target Energy consumption/$ Equipment discount/$ Distance/km Freight/$ Filling ratio Cost/$
80% 0 0 50 163 50% 390 5531)5532)
30 2091)4182) 178 50 46 0 74 5071)7162)
80% 0 0 100 325 50% 390 7151)7152)
30% 2091)4182) 178 100 93 0 74 5541)7632)
Incineration
Drying Incineration Incineration Burnt residue Composite Ben/$
Target Energy consumption/$ Equipment discount/$ Operation/$ Equipment discount/$ NaOH/$ Freight/$ Landfill/$
60% 1461)2932) 124 60 365 128 13 20 8561)10022)
10% 2281)4552) 193 27 162 128 13 20 7711)9982)
Composting
Energy consumption / ￥ equipment discount / ￥ loss of conditioner / ￥ total cost / ￥ sales / ￥ total benefit / ￥
391)782) 200 75 3141)3532) 410 961)572)
1) Electricity price to take 0.30 ￥ / (kW?h); 2) electricity price to take 0.60 ￥ / (kW?h)
A variety of treatment type of treatment cost estimates and knots shown in Table 2 by Table 2 know that the sludge treatment and disposal of composting type of this
Low about 300~350 ￥ / t DS; landfill type of about 500~760 ￥ / t DS incineration type of this high of about 800 ~ 1,000 ￥ / t DS composting this is lower than landfill type significantly lower than incineration type of with the increase in transport distance Landfill costs significantly higher than the composting costs outside the sludge incineration treatment investment operation and maintenance costs are high
Various treatment sludge landfill no resources to reap the benefits of zero; considering the level of calorific value of the sludge to receive the incineration of thermal energy energy of the lower net benefit impact; sludge drying dehydration effect stabilization effect limitations plus the drying process is prone to production of explosions fertilizer effect is slow, etc. It is appropriate to advocate; the product sales of the good situation of the same price of electricity with the composting treatment profit of 50~100 ￥ / t DS
2.2 Various treatment and disposal technology advantages and disadvantages
The current Ministry of landfill design and construction standards are low, the lack of pollution control measures to save the stability of the poor and other problems lead to the emission of gas odor pollution of the water can ensure the safety of landfill waste to delay the pollution did not end up eliminating the pollution of some of these problems to reduce the extent of the development of the physical characteristics of sludge to be disposed of low standards for the sludge to be disposed of in landfill treatment costs increased example of the German requirements Landfill sludge dry basis content of less than 35% to avoid the sludge organic matter to avoid water pollution 1992 German issued a "technical outline for the control and disposal of municipal waste" requires that from 2005 onwards, any landfill disposal of material with organic matter content of more than 5% [15] means that even after drying to meet the requirements of the landfill sludge landfill face landfill, the public and regulatory and other heavy pressure landfill costs are gradually rising in recent years, and outside of the proportion of landfill disposal of sludge is more and more [6].
Whether to promote composting treatment of municipal sludge should first effectively assess the potential environmental risks of sludge composting Du Bing et al. [16] showed that compared with the outside of a typical sewage treatment plant in Beijing phenols, phthalates, cyclic aromatic hydrocarbons are in the lower level of pollution composting treatment of sustained high temperature to ensure that kill germs to ensure the safety of sludge for agricultural use Chen Tongbin et al. [17] Heavy metal content of municipal sludge and its changing trends Research results show that the average content of my city sludge is generally low metal content basically does not exceed the agricultural standards [18] and shows a gradual decline in recent studies have proved: science and rationality of urban sludge agricultural use of soil and agricultural products to create heavy metal contamination problems [19] my city sludge soil use of heavy metal environmental risk is not as serious as imagined
Incineration reduction of a significant water content of 80% sludge incineration volume reduction rate of more than 90% sludge Containing a variety of organic matter incineration yield harmful substances dioxin, sulfur dioxide, hydrochloric acid, etc. by the internal incineration technology limitations dioxin pollution has not yet solved the problem of heavy metal fumes and combustion ash can create a second pollution outside the incineration waste sludge nutrients than the three treatment and disposal of sludge incineration accounted for the area of the integrated cost of the high equipment and maintenance requirements of the high risk of environmental protection more than some of the advantages are limited to the sludge incineration technology is widely used
In summary, the composting processing Realize sludge resource utilization Section reasonable application to ensure the safety of health and heavy metal safety with the more economic sludge treatment and disposal technology main development to the market sales point of view sludge composting product sales channels to be improved various treatment advantages and disadvantages are summarized in Table 3 (page)
2.3 The impact of electricity prices and government subsidies
Electricity prices affect sludge treatment and disposal of this tariff of 0.60 ￥/(kW?h) incineration for sewage sludge
Treatment and disposal type Income and Expenditure Balance/(￥?t-1) 1) Technical Difficulty Site Requirements Can Resourcefulness Degree of Harmfulness
Landfill -507~ -763 Simple Able to Delay Pollution, Not Eliminate Pollution Risks
Composting 57~96 Simpler More Able to Heavy Metals Lower Than Agricultural Use The heavy metals are lower than the agricultural standard to meet the requirements of pollution
Incineration -771~ -1000 Technical equipment requirements are high can tail gas can bring two pollution
1) Transportation distance of 100 km, the price of electricity 0.60 ￥ / (kw?h), 80% moisture content landfill is slightly lower than the cost of landfill of 30% moisture content, which accounted for 5.25 times, a comprehensive consideration to take the 30% landfill
Sludge moisture content of 80% and 60% landfill accounted for 30% and 60% landfill respectively. and 60% landfill accounted for 30% landfill 5.25 times, 1.75 times the government through subsidies to reduce the price of electricity and other regulatory means of sewage treatment inputs reasonable allocation of its sludge treatment unit to reduce the sludge treatment unit incineration, landfill accounted for the reduction of composting government subsidies to play the role of economic leverage to regulate the inputs and outputs of the sludge industry is conducive to the healthy development of the sludge treatment and disposal industry in general, the treatment and disposal of sludge should be suitable for the government to subsidize
3 Conclusion
(1) sludge composting cost changes with the price of electricity about 300~350 ￥ / t DS compost sales to compensate for the Ministry of treatment costs so that sludge composting to reach a micro-profit level reasonable application of compost to provide nutrients organic sludge treatment and disposal technology important to
(2) sludge landfill operation is simple its cost of about 500~760 ￥ / t DS is higher than the composting treatment considerations of the soil resource scarcity and second pollution problems and developed countries experience. The experience of developed countries shows that sludge landfill is gradually limited and its application ratio should be gradually reduced
(3) Sludge incineration has obvious reduction effect, and its initial investment and operating costs are high, with a comprehensive cost of about 771~1000 ￥/t DS, and its equipment maintenance is complicated, and its tail gas treatment creates secondary pollution
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