Source: Battelle Memorial Institute, Columbus Laboratories. A study to identify opportunities for increased solid waste utilization. Book 2, v.2. U.S. Environmental Protection Agency, 1972. [Distributed by National Technical Information Service, Springfield, Va. as Publication PB 212 730.]

Source: Battelle Memorial Institute, Columbus Laboratories. A study to identify opportunities for increased solid waste utilization. Book 2, v.3. U.S. Environmental Protection Agency, 1972. [Disrtibuted by National Technical Information Service, Springfield, Va. as Publication PB 212 730.]

1 271,000 tons of lead used in tetraethyl lead for gasoline and 125,000 tons of lead used in oxides and chemicals are not included since there is no possibility for its recovery.

Source: Battelle Memorial Institute, Columbus Laboratories. A study to identify opportunities for increased solid waste utilization. Book 2, v.4. U.S. Environmental Protection Agency, 1972. [Distributed by National Technical Information Service, Springfield, Va. as Publication PB 212 730.]

recycled is the form and location in which it occurs. Most of the nonferrous scrap that is easily accessible is recycled. However, there are certain types of scrap that are too contaminated and too widely scattered to allow economical recovery despite the high value of the materials (dealer's buying prices range from $60 to $920 per ton). For example, copper in cartridge brass and lead in ammunition is usually widely scattered over the country-side. Zinc is usually used as an alloying agent and coating and thus is extremely difficult to separate. Aluminum occurring in consumer durables, transportation vehicles, and construction is often only a small part of the product and thus much of it is never recovered. Aluminum used in packaging and ending up in the municipal waste stream cannot be economically recovered at present. It could only be feasibly separated as part of a large reclamation system where other materials (constituting a higher percentage of the waste) were also recovered.

An interesting perplexity of nonferrous metals recycling is that for some of the metals, copper is a good example, the scrap dealers

Source: Battelle Memorial Institute, Columbus Laboratories. A study to identify opportunities for increased solid waste utilization. Book 2, v.5. U.S. Environmental Protection Agency, 1972. [Distributed by National Technical Information Service, Springfield, Va. as Publication PB 212 730.]

perceive that they are pulling in about all that is available. Their estimate of the recycling ratio would be much higher than the actual.

GLASS RECYCLING

Status and Trends

In 1967 the glass manufacturing industry produced 12.8 million tons of glass. This production was divided among the three major segments of the industry: containers, flat glass, and pressed and blown glass. Containers, the most significant segment, accounted for 8.9 million tons, while flat glass accounted for 2.1 million tons and blown glass for only 1.8 million tons.

Glass constitutes only 6 to 8 percent by weight of municipal solid waste. There is virtually no recovery of glass from mixed waste, but a small amount of glass is recycled through voluntary collection centers and cullet dealers. Compared to other materials, glass is among the lowest in recycling ratios (about 4.5 percent of consumption) when home scrap (scrap generated in the glass manufacturer's plant) is excluded. Of a total of 12.8 million tons of glass produced in 1967, purchased cullet consumption was approximately 580,000 tons.17

Sources and Markets

Only a minute portion of glass waste (almost exclusively flat glass), is associated with industrial sources. Thus, municipal waste is the main potential source for old glass for recycling. In 1968, there were about 11.6 million tons of glass in municipal solid waste.

The best sources of quality cullet have been declining. Clear glass milk bottles and returnable glass containers rejected from bottle washing operations, major sources of cullet in the past, are gradually disappearing. Sorting, collection, and delivery costs have risen, principally because these operations are highly labor intensive. Plants have not been maintained and equipment has not been purchased due to limited capital of the few dealers still in operation. As the quality and availability of purchased cullet has deteriorated, its use in the glass industry has declined.

The glass container segment of the industry, which accounts for over 70 percent of the total glass tonnage output, purchased only about 100,000 tons of cullet or 1 percent of its raw materials consumption in 1967. This percentage is significantly lower than in the other two segments of the industry, largely because of an increase in utilization of in-plant cullet. Flat glass producers purchased 10 percent, or 244,000 tons, and pressed and blown glass producers 12 percent, or 256,000 tons.18

In addition to the use of purchased cullet in glass furnaces, there are several alternatives for cullet utilization. The most widely publicized alternative is in "glasphalt," a road surfacing material in which cullet replaces part of the asphalt aggregate. Initial testing results at the University of Missouri indicate that glasphalt is equal to or superior to conventional asphalt. However, cullet would have to compete economically with asphalt aggregate, which ranges in price from $1.50 to $5.00 per ton delivered to the asphalt plant. Present cullet prices are significantly higher than this amount.

Other proposed uses for cullet include construction materials, such as glass-cement blocks, and cullet-terrazzo. Experiments to determine feasibility of cullet utilization in these products are currently underway.

Problems and Issues

The glass industry has certain characteristics that make high levels of recycling from waste much more favorable in the glass industry than other industries. First, the manufacture of glass containers is essentially a one-step process, starting with raw materials and ending with the finished product. And second, cullet

can be substituted for virgin raw materials in large percentages, provided that the cullet meets minimum specifications of colors, cleanliness, and purity. From a technology standpoint, glass manufacture from 100 percent cullet appears possible.

There are, however, two problem areas: comparative economics and the recovery of cullet from mixed waste. With respect to economics the cost of virgin raw materials averages $15.48 per ton batch as compared to a range of from $16.00 to $22.50 per ton batch of cullet (both include freight charges to the plant). Processing cost differentials are not significant. The conversion of an existing plant to use increased quantities of purchased cullet would cost from $50,000 to $100,000, depending upon the plant, but the changeover could be accommodated within a framework of normal periodic plant improvements. A new plant designed to use cullet would be no more costly than a new plant designed for virgin materials.19

The recovery of large quantities of cullet from municipal waste is dependent on the development of a technical process for separation and upgrading of the cullet. However, the possibility of source separation of glass containers in the home for separate collections is an alternative that cannot be eliminated. Neither traditional cullet dealers nor voluntary citizen delivery of glass to recycling centers are likely to increase the cullet flow by more than a few percent.

Mechanical separation methods for removing glass from other components of municipal waste are still under development. One promising system that combines density classification and optical color sorting is currently being tested at Franklin, Ohio, while other methods, including one developed by the Bureau of Mines, are not yet ready for a comprehensive test.

Until the technology is further developed, utilization of purchased cullet on a large scale does not appear possible. Further, since glass is only a small percentage of solid waste, complete glass recovery from mixed waste is not likely to come about until full scale recovery centers, that are concerned with all major materials, are set up.

Unless source separation of glass containers is found to be feasible, utilization of purchased cullet on a large scale appears to be closely tied to development of full scale municipal resource recovery centers. The glass coming out of such systems will not be attractive to the glass industry on a cost basis, however, unless economic incentives are provided.