for determining composition Residential msw The procedure for residential MSW involves unloading and analyzing a quantity of residential waste in a controlled area of a disposal site that is isolated from wine and separate from other operations. A representative residential sample might be a truckload resulting from a typical weekday collection route in a residential area. A mixed sample from an incinerator storage pit or the discharge pit of a shredder would also be representative. Common sense is important in selecting the load to be sampled lation of vard wastes( not be typical. To ensure that the results obtained are representative, a large enough sample must be examined. It has been found that measurements made on a sample size of The authors have obtained similar results in field studies performed from the same waste load- insignificantly from measurements made on samples of up to 1700 Ib taker in Hawaii and at Davis California To obtain a sample for analysi load is first quartered. One part is then selected for additional uartering until a sample size of about 200 lb is obtained. It is important to each selected quarter regardless of the odor or physical decay. and to make sure that all the components are measured. Only in this way can some degree of randomness and unbiased selection be Commercial and Industrial MSw wastes involves the analysis of representative waste samples taken directly from the so mixed waste load in a collection vehicle. Because commercial and industrial sources are so variable statistically valid sampling is seldom possible. Estimation of the distribution of waste components and quantities for these activities remains an art form 13-5 Types of Materials Recovered from MSw The purpose of this section is to identify the types of materials that are now separated from MSw recycling and introduces and discusses briefly the importance of materials specifications in processing and marketing of recovered materials. Knowledge of the waste materials that are now recovered for reuse and recycling is important in the conduct of waste generation and diversion Materials Commonly Separated from Msw The most common ones from MSW are aluminum, paper, plastics, glass, ferrous metal, nonferrous etal, yard wastes, and construction and demolition wastes. Each is considered briefly in the following discussion Aluminum recycling is made up of two sectors: aluminum cans and secondary aluminum Secondary aluminum includes window frames, storm doors, siding, and gutters. Because secondary materials are of different grades, specifications for recycled aluminum should be checked, to recover the maximum value when selling separated materials to brokers. The demand for recycled aluminum cans is high, as it takes 95 percent less energy to produce an aluminum can from an existing can than from ore he principal types of waste paper that are recycled are old newspaper cardboard, high-grade paper, and mixed paper. Each of these four grades consist of individual grades, which are denned according to the type of fiber. source, homogeneity, extent of printing and physical or chemical characteristics. High-grade paper includes office paper, reproduction paper, computer printout, and other grades having a high percentage of long fibers. Mixed grades include paper with high ground-wood content, such as magazines; coated paper; and individual grades containing excessive percentages of outthrows"(papers of lower grades than the grade specified) Plastics. Plastics can be classified into two general categories: clean commercial grade scrap and post-consumer scrap. The two types of post-consumer plastics that are now most commonly recycled are polyethylene terephthalate(Pete/l), which is used for the manufacture of soft drink bottles, and13-8 for determining composition. Residential MSW The procedure for residential MSW involves unloading and analyzing a quantity of residential waste in a controlled area of a disposal site that is isolated from wine and separate from other operations. A representative residential sample might be a truckload resulting from a typical weekday collection route in a residential area. A mixed sample from an incinerator storage pit or the discharge pit of a shredder would also be representative. Common sense is important in selecting the load to be sampled. For example, a load containing the weekly accumulation of yard wastes (leaves) during autumn would not be typical. To ensure that the results obtained are representative, a large enough sample must be examined. It has been found that measurements made on a sample size of about 200 lb vary insignificantly from measurements made on samples of up to 1700 lb taken from the same waste load . The authors have obtained similar results in field studies performed in Hawaii and at Davis, California. To obtain a sample for analysis, the load is first quartered. One part is then selected for additional quartering until a sample size of about 200 lb is obtained. It is important to maintain the integrity of each selected quarter, regardless of the odor or physical decay, and to make sure that all the components are measured. Only in this way can some degree of randomness and unbiased selection be maintained. Commercial and Industrial MSW The field procedure for component identification for commercial and non-process industrial solid wastes involves the analysis of representative waste samples taken directly from the source, not from a mixed waste load in a collection vehicle. Because commercial and industrial sources are so variable, statistically valid sampling is seldom possible. Estimation of the distribution of waste components and quantities for these activities remains an art form. 13-5 Types of Materials Recovered from MSW The purpose of this section is to identify the types of materials that are now separated from MSW for recycling and introduces and discusses briefly the importance of materials specifications in the processing and marketing of recovered materials. Knowledge of the waste materials that are now recovered for reuse and recycling is important in the conduct of waste generation and diversion studies. Materials Commonly Separated from MSW The most common ones from MSW are aluminum, paper, plastics, glass, ferrous metal, nonferrous metal, yard wastes, and construction and demolition wastes. Each is considered briefly in the following discussion. Aluminum. Aluminum recycling is made up of two sectors: aluminum cans and secondary aluminum. Secondary aluminum includes window frames, storm doors, siding, and gutters. Because secondary materials are of different grades, specifications for recycled aluminum should be checked, to recover the maximum value when selling separated materials to brokers. The demand for recycled aluminum cans is high, as it takes 95 percent less energy to produce an aluminum can from an existing can than from ore. Paper. The principal types of waste paper that are recycled are old newspaper cardboard, high-grade paper, and mixed paper. Each of these four grades consist of individual grades, which are denned according to the type of fiber, source, homogeneity, extent of printing, and physical or chemical characteristics. High-grade paper includes office paper, reproduction paper, computer printout, and other grades having a high percentage of long fibers. Mixed grades include paper with high ground-wood content, such as magazines; coated paper; and individual grades containing excessive percentages of "outthrows" (papers of lower grades than the grade specified). Plastics. Plastics can be classified into two general categories: clean commercial grade scrap and post-consumer scrap. The two types of post-consumer plastics that are now most commonly recycled are polyethylene terephthalate (PETE/1), which is used for the manufacture of soft drink bottles, and