For a long time, China's urban waste treatment and disposal is mainly landfill-based, with the continuous improvement of China's environmental protection laws and regulations, people's awareness of environmental protection, landfill as a single disposal method is less and less adaptable to the requirements of waste treatment "reduction, resource utilization, harmlessness," more cities are inclined to waste disposal diversification, so that the waste generated by each region is also different from the other. More and more cities tend to diversify the waste treatment, so that the environmental impact, economic and social benefits of domestic waste treatment and disposal can be optimized. The physical and chemical properties of municipal garbage are directly related to the effectiveness and accuracy of garbage treatment and operation, so it is very important to analyze its characteristics.
At the same time in today's serious environmental pollution, in the scope of comprehensive management of municipal garbage more and more urgent need to use including waste management, characterization, collection, transportation, transit, treatment, disposal, comprehensive utilization and service in all aspects of the system of special facilities and machinery and equipment, including a complete advanced management system. The investigation of the composition and characteristics of municipal waste is an important part of this integrated management system, which helps to identify the various sources of waste generation, potential recyclable energy, and estimate the physical, chemical, and thermal properties of the various components, thus ensuring the selection of the correct treatment and disposal technologies and facilities, and becoming an important basis for ensuring the proper functioning of the whole system as a whole.
It can be seen that the correct grasp of the physical and chemical characteristics of urban waste, for the city to formulate comprehensive waste management planning, selection of appropriate collection and treatment methods, equipped with specialized facilities and machinery and equipment to provide the necessary basis.
Survey content and commonly used norms and standards
According to the Ministry of Construction industry standards (CJ/T3039-95) "sampling and physical analysis of municipal garbage" stipulates that the basic physical and chemical characteristics of municipal garbage mainly include:
(1) garbage components (%): paper, rubber and plastic, cloth, bamboo and wood, food waste, Peel, glass, metal, slag, hazardous (such as batteries), others;
(2) Bulk weight (kg/m3)
(3) Moisture content (%):
(4) Ash (%);
(5) Volatility (%);
(6) Calorific value (kJ/kg;);
(7) Elements: C, H , N, S, O, Cl (%);
(8) Heavy metals: Cr, Hg, Cd, Pb, As (mg/kg).
Commonly used norms and standards
"Classification of Urban Waste Generating Sources and Discharge of Waste" (CJ/T3033-1996);
"Norms for Investigation and Statistics on the Composition of Urban Resident's Domestic Waste" (DB/J08-25-92);
"Methods for Sampling and Physical Analysis of Urban Domestic Garbage Sampling and Physical Analysis Methods (CJ/T-3039-95);
Methods for Determining the Calorific Value of Coal (GB213-2003);
Methods for Industrial Analysis of Coal (GB212-2001);
General Rules for Methods of Elemental Analyzer (JY/T017-1996);
General Rules for Methods of Elemental Analyzer (JY/T017-1996)
Computerized 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 characteristics such as water content, weight, organic content, calorific value, etc. are affected by a variety of factors, so that the physical and chemical characteristics of domestic waste can be analyzed by the computerized analysis system between different cities, between different urban areas of the same city or between the same city, or even between the same urban area in different seasons or the same waste treatment plant (site). Therefore, 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 between different seasons in the same urban area or different time periods in the same waste treatment plant (yard). Therefore, the determination of the physical and chemical properties of domestic waste and its changes has become a regular and repetitive work.
The widely used method of physical and chemical properties of domestic garbage is not only troublesome and time-consuming, but also due to the inhomogeneity of domestic garbage, the measured data are more dispersed, and it is difficult to obtain the physical and chemical properties of incoming garbage during the operation of garbage treatment plants.
The computer analysis system proposed here is developed on the basis of FoxPro forWindows technology using weighted calculations of typical characteristic values of waste constituents, and it is able to derive the main physical and chemical characteristic values of domestic wastes more accurately and quickly and conveniently.
1Waste Composition Analysis Method
The waste composition analysis method is a more accurate and practical method for determining the physical and chemical properties of domestic waste developed and used by the authors in their work.
The method is to analyze the composition of at least 100kg of domestic waste samples (mixed large samples) obtained by using the quadrature method, and then to determine the physicochemical characteristic values of each component in accordance with the specified specimen (single-component small samples) and the method, and then calculate the physicochemical characteristic values of the domestic waste according to the weighting of the percentage of each component.
The physical and chemical properties of domestic waste depend on the percentage of each component, but also with the moisture state of domestic waste. Determination of the physical and chemical properties of the components of domestic waste, according to the different moisture content of domestic waste is divided into three categories: Type 1 for the natural state of the value of the properties of the state of the moisture is the natural moisture content of the components; Type 2 for the state of the value of the properties of the high moisture state, which increases the moisture of foreign water (mainly rainwater); Type 3 for the state of the value of the properties of the low moisture state, mainly evaporation of some of the moisture drying properties of the value of the determination.
Wuhan Urban Construction College living area garbage sampling, experimental data processing shows that for the same batch of specimens, the physical and chemical properties of domestic waste using mixed large-sample composition analysis method weighted calculation of the value of the error is much smaller than the use of conventional mixed small-sample determination. In addition, the physicochemical property values of single-component samples can be repeated many times in a certain area and under certain conditions, and the main physicochemical property
values of garbage can be derived quickly and conveniently by analyzing only the garbage constituents.
2 System Composition
The rapid analysis system for the physical and chemical property values of household garbage is realized in Windows environment by using FoxPro database, and the program files are programmed in FoxPro language. The functions of the system are realized by various operations on the database file.
2.1 Database files:
2.1.1 Database files of the system itself:
When the system is established, the records and structures of the typical values and range values of the physical and chemical properties of each component of the garbage are established at the same time, and they are generally kept unchanged.
2.1.2 Database files created by the user:
Under the structure and window given by the system, data are entered by the user and can be modified at any time.
2.1.3 Temporarily generated database file: (Source: Internet) This library is used to store various intermediate results generated during the operation of the system, and the temporary data is automatically cleared with the exit of the system.
2.2 System Functions:
2.2.1 Data Input:
After initialization of the system, a window will be opened for the user to select the state of garbage moisture with the mouse; and another window will be opened for the user to input the percentage of each constituent of the garbage measured by the multi-sampling, which will be processed by the system as the average value.
2.2.2 Calculation of Physical and Chemical Characteristics:
The main function of the system is to carry out the weighted calculation of physical and chemical characteristics such as moisture content, bulkiness, organic content and calorific value.
2.2.3 Output of results:
The results of the above calculations are output to the screen or printer in tabular form.
3 characteristics of the analyzing system
3.1 Reliable results:
The system's own database file is built on the basis of single-component small-sample measurement data, while the user database
is obtained by mixing the large samples, so compared with the conventional mixed small-sample measurements, the data results of the sample representative of the sample to be better and
Errors are smaller. smaller.
3.2 Fast acquisition of characteristic values:
This system exchanges data between FoxPrv databases, which enables high-speed access and is faster than earlier data
library management systems (such as DBASE and FORBASE).
3.3 Easy to set up the system:
As a result of taking full advantage of the FoxPro for Windows technology, the programming work is greatly simplified.
3.4 Simple user operation:
Entering FoxPro under the Chinese visualization environment, the user only needs to input the percentage of each component of the garbage according to the on-screen prompts, and
the system can automatically output the values of the garbage's main physical and chemical properties.
4Summary
The methodology and system structure of the Rapid Analysis System for Physical and Chemical Characteristics of Domestic Waste is widely applicable. Although it should be recognized that there are some limitations in the system's own database records, the user can change this database record by experimenting and obtaining typical values of the physical and chemical properties of each component of the garbage that are applicable to the local area.