Municipal waste stream

Fig. 2. Materials generated in the municipal waste stream from 1960 to 1995 (% of total generation), where (H) represents paper and paperboard, (H)...

Glass is a material having properties that provide attributes for many commercial products. As some of these products reach the end of thek useful life and are discarded, there is often the opportunity to have the glass recycled into other useful products. In many respects, this alternative is preferred over the glass entering a municipal waste stream for landfill disposal. 

Heavy metals have the potential to enter the water supply from the leachate or runoff from landfills. It is estimated that nonrecycled lead-acid batteries produce about 65% of the lead in the municipal waste stream. When burned, some heavy metals such as mercury may vaporize and escape into the air, and cadmium and lead may end up in the ash, making the ash a hazardous material for disposal. 

Table I. Materials Discarded Into the Municipal Waste Stream 1970-2000.

Organic waste is usually incinerated as part of mixed municipal waste stream. Depending on the facility and the energy use, this process can be regarded as either energy recovery or as disposal. Because the moisture content in organic waste is mostly very high (about 60%), the efficiency of such processes is quite poor. 

In order to evaluate the impact of batteries that are neither in home storage nor collected, it is necessary to evaluate the quantities of batteries present in the municipal waste streams. The mass balance of portable Ni-Cd batteries introduced into the market is presented in Figure 19. 

In the future, the practise of separation of municipal waste before incineration will be more popular. Then, Ni-Cd batteries could be easily removed from municipal waste streams by using an electro-magnet overband in order to remove all Ni-Cd batteries together with other ferro-magnetic materials. This technology is currently used in the Netherlands (CollectNiCad 2001). 

Some quantitative data regarding the contaminant concentrations in household waste fractions are available. In the paper and cardboard fraction, the quantities of heavy metals are relatively low compared to the total contamination by heavy metals in the total municipal waste stream. Newspapers, for example, contain very low concentrations of heavy metals compared to magazines, the color print of which contains heavy metals. Data from the National Household Waste Analysis conducted in Germany are listed in Table 9.2. The data reflect results that the separate collection of recyclables has on the concentrations of heavy metals and halogens in individual recyclable fractions and in the remaining waste steam. Before being mixed with the other waste, the organic fraction of household waste is as low as the fraction of... 

The most difficult for recycling is the commingled post-consumer waste (PCW), especially from the municipal waste stream. Complete PCW recycling plants are available from several equipment manufacturers at a cost of about 3-5 million for 1 ton/hr capacity. However, most reprocessors tend to assemble the reprocessing lines from individual units, frequently modifying the equipment to better suite individual conditions. The number of manufacturers for separate machines, viz. sorters, separators, grinders, washers, shredders, aggregators, classifiers, dryers, extraders, and others, runs into thousands. 

The problems associated with discarded batteries from the highly distributed domestic sources are complicated. They involve questions of social structures, economics, technology, and regulatory climates. The first problem is that of the efficient retrieval of discarded batteries. The next question that must be answered is what kinds of batteries may be allowed to enter municipal waste streams without treatment Another question is how will the consumers know which is which This is related to the question of the amounts of pollutants contributed by particular batteries relative to other sources of the same pollutants. It is not reasonable to consider batteries alone as a problem from the point of view of municipal solid waste (MSW) treatments when other sources contribute the same pollutants as well. Nickel/cadmium batteries are an example. Sources other than batteries contribute significant amounts of cadmium to MSW. The elimination of nickel/cadmium batteries from MSW or the elimination of cadmium from Ni/Cd batteries will not solve problems attributed to cadmium in MSW. 

Plastics (PL) comprise more than 8% of the total weight of the municipal waste stream and about 12-20% of its volume [ 146,147]. In 1992, approximately 30 mil-hon metric tons (33 milhon tons) of plastics were discarded in the United States only 14.7 million metric tons (16.2 milhon tons) were recycled. Current research on the use of recycled plastics in highway construction is wide and varied. 

Tertiary recycling is the production of basic chemicals or fuels from segregated plastic scrap or plastic material that is part of a municipal waste stream or other source. ... 

Product take-back requirements for electronics continue to spring up around the world. In Ontario, the government added electronics and electrical equipment of all kinds to the list of items that are to be diverted from disposal. The plan is to require a company called Waste Diversion Ontario to develop a program to handle the diversion of waste electronics from the municipal waste stream. ... 

PE represents the largest constituent of plastics in the municipal waste stream and the fraction is mainly composed of high-density polyethylene (HDPE) packaging materials. Recycling this type of waste packaging material yields a stream of recycled plastic that is highly homogeneous and consistent [8]. 

The new Waste Framework Directive has set a 50% recycling target for household waste. The directive does not stipulate what waste should apply to the municipal waste stream as a whole or individual material fractions within this stream [20]. 

This low level of plastic recycling can be directly attributed to two main factors (i) the difficulties associated with separation of plastic packaging from municipal waste streams, and (ii) costs ballooning up to ten times for commingled streams compared to well defined single soirrce streams such as PET bottles [68]. 

Another method to souree reduetion is to increase incentives for recycling. Many communities in the United States are implementing variable rate pricing for waste disposal (also known as Pay As You Throw - PAYT), which has been effective in reducing the size of the municipal waste stream. 

Plastics waste is found in refuse from industry and household. Its state varies from one source to the next. The scrap from polymer processing is often clean, whereas that from the building sites or municipal waste streams usually is contaminated. Depending on the type of waste and the technological possibilities, four methods of utilization of plastics waste are distinguished ... 

Surita SC, Tansel B (2014) Emergence and fate of cychc volatile polydimethylsiloxanes (D4, D5) in municipal waste streams release mechanisms, partitioning and persistence in air, water, soil and sediments. Sci Total Environ 468 69 46-52... 

It is unlikely that any revenue could be generated by landfill, since the non-me-tallic residue is voluminous, compressible, and lacks the properties desirable in hard-core. Current technology cannot profitably separate individual plastics from shredder residues to provide fractions which can be used in applications similar to the original use. It has been estimated that, in the period 1985-1990, only about 25% of the total quantity of plastics waste is likely to be diverted from the municipal waste stream and recycled. Of this, some 27%, i.e. approximately 7% of the total is likely to come fi om the transport sector in the United States. 

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