For a long time, the treatment and disposal of municipal solid waste in China is mainly landfill. With the continuous improvement of China's environmental protection laws and regulations and the enhancement of people's awareness of environmental protection, landfill, a single disposal method, is increasingly unsuitable for the requirements of "reduction, recycling and harmlessness" in garbage disposal, and more cities tend to diversify garbage disposal to optimize the environmental impact, economic benefits and social benefits generated by domestic garbage disposal. The physical and chemical properties of MSW are directly related to the effectiveness and accuracy of MSW treatment and operation, so it is very important to analyze its characteristics.
At the same time, in today's serious environmental pollution, it is more and more urgent to use a complete and advanced management system including garbage management, characteristic research, collection, transportation, transshipment, treatment, disposal and comprehensive utilization, as well as special facilities and mechanical equipment serving all aspects of this system. Investigation on the composition and characteristics of municipal solid waste is an important part of this integrated management system, which helps to identify various waste sources and potential recyclable energy sources, and estimate the physical, chemical and thermal characteristics of various components, thus ensuring the correct selection of treatment and disposal technologies and facilities, and becoming an important basis for ensuring the normal operation of the whole system.
It can be seen that a correct understanding of the physical and chemical characteristics of municipal solid waste provides the necessary basis for the city to formulate a comprehensive waste management plan, choose appropriate collection, transportation and treatment methods, and equip it with special facilities and mechanical equipment.
Investigation contents and commonly used norms and standards
According to the industry standard of the Ministry of Construction (CJ/T 3039-95) Sampling and Physical Analysis Methods of Municipal Domestic Waste, the basic physical and chemical characteristics of municipal domestic waste mainly include:
(1) Waste composition (%): paper, rubber, cloth, bamboo, kitchen waste, peel, glass, metal, slag, harmful substances (such as batteries) and others;
(2) Bulk density (kg/m3)
(3) Water content (%)
(4) Ash (%);
(5) Volatile matter (%);
(6) calorific value (kj/kg; );
(7) Elements: C, H, N, S, O, Cl (%);
(8) Heavy metals: chromium, mercury, cadmium, lead and arsenic (mg/kg).
General specifications and standards
Source Classification and Waste Discharge of Municipal Waste (CJ/T3033-1996);
Code for Investigation and Statistics of Domestic Waste Composition of Urban Residents (DB/J08-25-92);
Sampling and Physical Analysis Methods of Municipal Domestic Waste (CJ/T-3039-95);
Determination of calorific value of coal (GB 213-2003);
Industrial analysis method of coal (GB 212-2001);
General rules of elemental analyzer method (JY/T0 17- 1996)
Computer analysis system for physical and chemical characteristics of domestic waste
The composition of domestic waste can be regarded as a multivariate function system, and its physical and chemical properties, such as water content, bulk density, organic matter content and calorific value, are affected by many factors, so there may be significant differences in the physical and chemical properties of domestic waste between different cities, or between different urban areas of the same city, or even in different seasons of the same urban area or at different time periods of the same waste treatment plant (field). Therefore, it is a regular and repetitive work to measure the physical and chemical characteristics and changes of domestic waste.
At present, the widely used mixed sample method for determining the physical and chemical characteristics of domestic waste is not only troublesome and time-consuming, but also the measured data are scattered to a great extent due to the heterogeneity of domestic waste. In addition, it is difficult to obtain the physical and chemical characteristics of domestic waste in real time during the operation of the waste treatment plant.
Based on FoxPro forWindows technology, the computer analysis system proposed here is developed by using the weighted calculation of typical characteristic values of garbage components, which can obtain the main physical and chemical characteristic values of domestic garbage more accurately, quickly and conveniently.
1 waste composition analysis method
The analysis method of waste composition is a more accurate and practical method to determine the physical and chemical characteristics of domestic waste developed and used by the author in his work.
The method is to analyze the components of the domestic waste samples (mixed samples) of at least 100kg obtained by the quartering method, and then determine the physical and chemical characteristics of each component according to the specified sample (single component sample) and method, and then calculate the physical and chemical characteristics of the domestic waste according to the percentage of each component.
The physical and chemical properties of domestic waste depend not only on the percentage content of each component, but also on the moisture state of domestic waste. The measured physical and chemical characteristic values of each component of domestic waste are divided into three categories according to the different moisture content of domestic waste: 1 category is the characteristic value of natural state, and the moisture in this state is the natural moisture content of each component; The second is the characteristic value of high humidity state, and its moisture increases the external moisture (mainly rainwater); The third category is the characteristic value of low moisture state, which is mainly determined after partial moisture evaporation and air drying.
The experimental data processing shows that for the same batch of samples, the error of weighted physical and chemical characteristics of domestic waste by mixed large sample component analysis method is far less than that by conventional mixed small sample determination. In addition, the physical and chemical properties of single-component samples can be reused in certain areas and under certain conditions, and the main physical and chemical properties of garbage can be obtained quickly and conveniently by analyzing the components of garbage.
Value.
2 system composition
Using FoxPro database, the rapid analysis system of physical and chemical characteristics of domestic waste is realized in Windows environment, and the program files are written in FoxPro language. The function of the system is realized by operating database files.
2. 1 database file:
2. 1. 1 database file of the system itself:
When the system is established, the typical values and range values of physical and chemical characteristics of each component of garbage are recorded, and the structure is established, which generally remains unchanged.
2. 1.2 database files created by users:
Under the structure and window given by the system, users can input data and modify it at any time.
2. 1.3 temporary database file: (Source: Internet) This library is used to store various intermediate results generated when the system is running, and the temporary data will be automatically cleared when the system exits.
2.2 System functions:
2.2. 1 data input:
After the system is initialized, a window is opened for the user to select the moisture state of the garbage with the mouse; In addition, a window is opened for users to input the percentage of each component of garbage measured by multi-point sampling, and the system will treat it as an average value.
2.2.2 Calculation of physical and chemical characteristic values:
The main function of the system is to calculate the weighted values of physical and chemical characteristics such as water content, bulk density, organic matter content and calorific value.
Output of results:
Output the above calculation results to the screen or printer in tabular form.
3 characteristics of the analysis system
3. 1 The calculation result is reliable:
The database file of the system itself is based on the measurement data of a single component sample, while the user database
It is obtained by mixing large samples, so compared with the conventional mixed small sample determination, the data results are better and more representative.
The error should be small.
3.2 Fast collection of eigenvalues:
The system exchanges data between FoxPrv databases, and can realize high-speed access compared with the earlier data.
Library management systems (such as DBASE and FORBASE) are faster.
3.3 The system is easy to establish:
Making full use of FoxPro for Windows technology greatly simplifies the programming work.
3.4 User operation is simple:
When inputting FoxPro in Chinese visual environment, users only need to input the percentage of each component of garbage according to the screen prompts.
The system can automatically output the main physical and chemical characteristics of garbage.
4 abstract
The method and system structure of rapid analysis system for physical and chemical characteristics of domestic waste have wide applicability. Although it should be admitted that the database record of this system has some limitations, users can change the database record by obtaining the typical values of physical and chemical characteristics of various components of garbage suitable for the local area through experiments.