Solid waste processing

Use of specific forms of radiant energy, infrared, ultraviolet, dielectric heating, etc., can allow specific separations to be made. The separation of clear and colored grains of glass and the separation of different metals are possible apphcations of the thermoadhesive method being considered in the field of solid-waste processing. 

Disposal The final func tional element in the sohd-waste-management system is disposal. Disposal is the ultimate fate of all solid wastes, whether they are wastes collected and transported direc tly to a landfQl site, semisolid wastes (sludge) from industrial treatment plants and air-pollution-control devices, incinerator residue, compost, or other substances from various solid-waste processing plants that are of no further use. 

Processing Techniques for Solid Wastes Processing techniques are used in solid-waste-management systems to (I) improve the efficiency of the systems, (2) to recover resources (usable materials), and (3) to prepare materials for recoveiy of conversion produc ts and energy. The more important techniques used for processing solid wastes are summarized in Tables 25-61 and 25-62. 

Environmental engineering Wastewater and industrial waste treatment Biological waste treatment Solid waste processing Soil and hazardous waste management... 

The data are the basis on which to determine the recoverable components and energy, process design, construction of the solid-waste processing plant, needs in equipment, and process economics in a solid waste processing plant. 

In solid waste-processing plants, classification has four purposes ... 

Trommel inclination, which usually varies between 2 and 5 degrees, affects the residence time of the waste material in the drum, as well as the trommel throughput. Other factors that affect the throughput are trommel diameter and filhng factor. Trommel screen is a valuable item of many solid waste-processing plants, as it appears to be a clogging resistant screen. 

Heavy media separation is a wet separation method and, as such, has been applied in a limited extension in solid-waste processing. It has been mostly used to separate aluminum, which is collected to the light fraction, from other materials in car recycling. 

Metal items constitute an appreciable amount of solid waste, with their percentage varying between 5 and 15 percent in most cases. As the revenue from solid-waste processing plants is derived from the sale of the separated products, among which ferrous and nonferrous metal items, the recovery and recycling of metallic objects support considerably the construction and operation of solid-waste treatment plants. The recycling of metal items is very important, as it contributes in mineral deposits conservation and in the prevention of environmental pollution from the oxidation and dissolution of various metals, being in alloyed form. 

Magnetic separation is a unit operation that is applied whenever metals with magnetic properties participate in the composition of the commingled waste. Magnetic separators are encountered in almost all the recycling plants, as they are very simple in operation, have a relahvely lower cost compared to the other equipment of a solid-waste processing plant, have a high efficiency (80 to 95 percent) and production rates, and short pay-hack period. 

There are also more types of conveyors, such as chain and moving floor conveyors, with relatively limited application in solid waste processing plants. 

Belt conveyors are the most widely used equipment for materials handling in solid waste processing plants, applied both for materials conveying as well as for hand sorting. 

This chapter describes the unit operations that could be applied in a solid-waste processing plant aiming to recover recyclable materials, refuse-derived fuel, as well as products for further chemical or biological processing. The tailings from solid-waste processing are rejected to the landfill. 

Anywhere spent nuclear liiel is handled, there is a chance that iodine-129 and iodine-131 will escape into the environment. Nuclear fuel reprocessing plants dissolve the spent fuel rods in strong acids to recover plutonium and other valuable materials. In the process, they also release iodine-129 and -131 into the airborne, liquid, and solid waste processing systems. In the U.S., spent nuclear fuel is no longer reprocessed, becau.se of concerns about nuclear weapons proliferation. 

Chesner WH, Collins RJ, Fung T (1986) The characterization of incinerator residue in the City of New York. Proc 1986 National Waste Processing Conf,ASME Solid Waste Processing Division, Washington, DC, p 534... 

Another example of complex solid waste processing originating from a phosphoric acid plant is the Gujarat State Fertilizer Company, Ltd., Baroda, India. The complex is composed of a Chemico DH phosphoric acid plant, with an installed capacity of 165 tpd, two trains of DAP with a capacity of 460 tpd, and an AS (ammonium sulfate plant) with a capacity of 470 tpd. 

In addition, it has been found that solid waste processes are insensitive to feedback and underestimate time lags between actions and responses. This insensitivity to feedback reflects a failure of the decision-making process to correctly assess the nature and significance of the solid waste management system, particularly the link between the decision and the environment. 

The wet solid waste processing subsystem consists of a built-in dewatering station. A High Int rity Container C) is filled with either dudges from the phase separator or bead resin from the spent resin tanks. Spent cartridge filters may also be placed in the HIC. 

---