Capital and Operational Costs

The large surface area of the packing in an air stripper promotes the transfer of volatile organic compounds to the vapor phase without undergoing any reaction with 

Prior to installation of an air stripper (20) to remove TCE, DIPE, and MTBE from a municipal water supply, GAC had been used for this purpose. Carbon bed life had decreased to 4-6 wk shortly before the air stripper was put on-line, at a regeneration cost of 32,000 per replacement. The total capital cost for the GAC system was approx 200,000, while the installed cost of the air stripper was approx 375,000. The yearly 

Analysis of iiffluent water quality prompted the selechon of air stripping over GAC for treatment of a contaminated surface water supply (7). Although the carbon units provided good adsorphon of TCE, rapid breakthrough of 1,1-dichloroethane and 1,1, 1-trichloroethane was noted. 

An air-stripping system designed to minimize energy requirements (8) was installed to remove volahle organic compounds at levels between 200 and 250 pg/L from drinking water supplied by a municipal well field. The system was capable of treahng 2.16 MGD (8,176 m /d) at effluent levels not exceeding 10 pg/L total VOCs. Total installed cost was approx 200,000, and operational costs were less than 20,000/yr. 

---

Both vacuum operation and the use of refrigeration incur capital and operating cost penalties and increase the complexity of the design. They should be avoided if possible. For a first pass through... 

In the case of a liquid recycle, the cost of this pressure increase is usually small. Pumps usually have low capital and operating costs relative to other plant items. On the other hand, to increase the pressure of material in the vapor phase for recycle requires a compressor. Compressors tend to have a high capital cost and large power requirements giving higher operating costs. 

Incineration. Incinerators were discussed in Sec. 11.1. When incinerators are used to treat gaseous pollutants in relatively low concentration, auxiliary firing from fuel or other waste material normally will be necessary. The capital and operating costs may be high. In addition, long duct lines are often necessary. 

The capital cost of most aqueous waste treatment operations is proportional to the total flow of wastewater, and the operating cost increases with decreasing concentration for a given mass of contaminant to be removed. Thus, if two streams require different treatment operations, it makes no sense to mix them and treat both streams in both treatment operations. This will increase both capital and operating costs. Rather, the streams should be segregated and treated separately in a distributed effluent treatment system. Indeed, effective primary treatment might mean that some streams do not need biological treatment at all. 

The cost of the capital depends on its source. The source of the capital often will not be known during the early stages of a project, and yet there is a need to select between process options and carry out preliminary optimization on the basis of both capital and operating costs. This is difficult to do unless both capital and operating costs can be expressed on a common basis. Capital costs can be expressed on an annual basis if it is assumed that the capital has been borrowed over a fixed period (usually 5 to 10 years) at a fixed rate of interest, in which case the capital costs can be annualized according to... 

Capital and operating costs will increase as more separator stages are added to the process line, so a balance has to be struck between increased oil yield and cost. It is uncommon to find that economics support more than 3 stages of separation and one or two stage separation is more typical. The increased risk of separation shut down is also a contributing factor in limiting numbers. 

The choice of technology, the associated capital, and operating costs for a chlor—alkaU plant are strongly dependent on local factors. Especially important are local energy and transportation costs, as are environmental constraints. The primary difference ia operating costs between diaphragm, mercury, and membrane cell plants results from variations ia electricity requirements for the three processes (Table 25) so that local energy and steam costs are most important. 

Capital and operating costs for soda ash production are extremely site specific (29,10). Key factors iaclude iafrastmcture development, freight to consumers, local energy and labor costs, and by-product saleabiUty. 1990 Hst price of bulk natural soda ash was 108/t, F.O.B. Wyoming. 

Table 13. Capital and Operating Costs for HCl Production by Process...

Other Le d Smeltings Processes. Stricter regulations concerning lead emissions and ambient lead in ak levels (see Airpollution), and the necessity to reduce capital and operating costs have encouraged the development of alternative lead smelting processes to replace the sinter plant—blast furnace combination. 

Producers have developed specific cell configurations to optimise electricity consumption, cell capital, and operating costs. Pacific Engineering Corp., Kerr-McGee Chemical Corp., Chedde Pechiney, Cardox Corp., Electrochemie Turgi, American Potash and Chemical, and I. G. Earbenindustrie each has a unique cell design. 

In a similar appHcation, Cape Industries has announced its intention to commission a solvent extraction plant to recover acetic acid from an effluent generated at its dimethyl terephthalate [120-61-6] faciHty (Wilmington, North Carolina) (44,45). The plant was commissioned in Eebmary 1995. In this case, the solvent will be CYANEX 923 extractant [100786-00-3], CYANEX 923 is also a phosphine oxide, but unlike TOPO is a Hquid and can be used without a diluent (46,47). This has the benefit of reducing plant size, capital, and operating costs. 

The benefits of high selectivity He in the abiUty to produce high purity cobalt in a limited number of stages. This minimises capital and operating costs. It is particularly important when the solution in question contains low concentrations of cobalt. Eor example, solutions derived from laterite deposits may only contain 0.5—2 g/L Co but 90—100 g/L Ni. 

Some alkylphenol appHcations can tolerate "as is" reactor products, most significantly in the production of alkylphenol—formaldehyde resins. These resins can tolerate some of the reactant and by-product from the alkylphenol reactor because they undergo purification steps. This resin production route has both capital and operating cost advantages over using purer alkylphenol streams as feedstock. For these savings, the resin producer must operate the process in such a way as to tolerate a more widely varying feedstock and assume the burden of waste disposal of some unreactive materials from the alkylphenol process. 

Subsequent separation of this solvent imposes substantial capital and operating cost penalties. A Bayer AG patent (37) claims use of a solvent in which DNT is soluble, but in which the TDA is practically insoluble. This allows separation and recycle of the solvent to the reactor without any distillation process. 

Food Processing. One of the first appHcations of RO was ia the food processiag (qv) iadustry. The primary advantage of RO over the traditionally used processes ia the food iadustry is that RO operates at low temperatures which can prevent the denaturation of some materials used ia foodstuffs. Because high temperatures are not required, energy costs are reduced as well. Moreover, RO is relatively simple ia terms of the equipment design. These factors lead ultimately to a reduction ia capital and operating costs, accompanied by an iacrease ia product quaUty. 

AH special processes involve extra capital and operating costs, time, and a reaUstic analysis of markets and procedures. Because of increasing quaUty demands, some form of ladle treatment has become essential in steelmaking of the 1990s. 

One physical method that has attracted some commercial interest is evaporation several evaporative plants were installed in Japan in the early 1970s, nearly all followed by incinerators for the sludge produced (60). They are, however, expensive in both capital and operating costs. The most recent evaporation systems use a process known as vapor recompression, which has the claimed advantage of much lower operating costs than the eadier evaporative processes used in the wool industry. Capital costs of these processes are still high. 

---