Optimum sampling of municipal solid wastes

Abstract

Quartering, random sampling, stratified sampling and cluster sampling methods are evaluated for precision and efficiency in the analysis of municipal solid wastes (MSW). The optimum method for sampling MSW is proposed and related to the object of the sampling. The main results are as follows: 1. 1. Based on observations made on the movement of tracers, the mixing stage in the quartering method can be done accurately if the weight of MSW is less than about 50kg. 2. 2. The more separation that is carried out in the quartering, the larger the relative error of the composition. However, the error is smaller if MSW is cut into smaller pieces before quartering. 3. 3. The relative error in the quartering process can be expressed by normal distribution. This probability model gives the relationship between the precision of estimation (relative error) and sample weight. 4. 4. The same relationship is also obtained with random sampling, stratified sampling and cluster sampling. 5. 5. If bulk density is used as a stratified variate, stratified sampling becomes an effective method for estimating the water content, low calorific value and several components of MSW.