suspended solids would be returned to the reactor 

 vessel with the stickwater. 



The bones, which are removed by screening, 

 are dried, packaged, and stored as bone meal. 

 The hydrolysate may be passed directly to the 

 wiped-film evaporator feed tank after screening. 

 If the hydrolysate is centrifuged for additional 

 oil removal, the insoluble solids are recombined 

 with the aqueous stream, concentrated by evap- 

 oration and either spray-dried or canned as fish 

 paste. 



Cost Estimates 



A computer program entitled "Engineering 

 Economic Model for Fish Protein Concentrate 

 Processes" has recently been prepared under a 

 Bureau of Commercial Fisheries contract with 

 the Chemical Engineering Department of the 

 University of Maryland. It estimates plant con- 

 struction and operating costs for various types 

 of FPC processes and has been used here in the 

 estimation of production costs for hydrolysates 

 of raw fish and fish press cake. 



Input data to the computer include: plant 

 size; operating days per year; costs of fish, util- 

 ities, and labor; depreciation and interest rates; 

 proximate composition of fish; and a current 

 cost index. Enzyme cost and eflfectiveness are 

 also included for the biological processes. 



From process flow sheets and distribution 

 equations, preferably based on experimental re- 

 sults, material and energy balances are com- 

 puted for each process. Major pieces of process 

 equipment are then sized and tabulated along 

 with estimated installed costs. Costs of spe- 

 cific pieces of process equipment, facilities, 

 fish handling systems, etc. provide a consistent 

 basis for comparison between alternate FPC pro- 

 cesses. 



Input data. — Cost estimates were based on 

 the assumption of fish costing 1 cent per pound 

 and composed of 127r oil, 16^/r protein, and 3% 

 ash. Electricity at 1.3('/KWH, fuel at 6<'/therm, 

 and labor at $4/hr were also assumed. The 

 charge for depreciation plus interest was set at 

 15 Sf per annum. Enzyme, costing $5/lb, was 

 specified at 0.1 lb. per 100 lb. of raw fish (soluble 

 product) and at 0.1 lb. per 100 lb. of press cake 

 (partially soluble product). 



Summary of results. — Equipment for each 

 process was sized and tabulated with estimated 

 installed cost on the computer print-outs. Es- 

 timated fixed capital costs for 200 ton/day plants 

 are listed in Table 16. A depreciation and in- 

 terest charge of 15'yi per year on fixed capital 

 costs was included in computations of total an- 

 nual operating costs for each process. 



Annual operating costs and production rates 

 computed by the Engineering Economic Model 

 were used to calculate production costs for dry 

 concentrates of fish protein. These cost esti- 

 mations for both 50 and 200 ton/day plants are 

 summarized in Table 17. By-product values of 

 $80 per ton of crude fish oil and $60 per ton of 

 bone feed were assumed for the computations. 



The estimated production cost for a soluble 

 FPC prepared by the biological process is a little 

 higher than that estimated for FPC prepared 

 by isopropanol (IPA) extraction of whole fish. 

 It is not as expensive, however, as one prepared 

 by IPA extraction of wet deboned hake. The 

 straight biological process has the advantage of 

 a lower capital cost than any of the other FPC 

 processes studied. 



Based on computer estimates the press cake 

 biological process yields a product that is sig- 

 nificantly cheaper than the IPA-extracted FPC. 

 If the residual oil can be suitably stabilized the 

 press cake product will add extra caloric value 

 as well as excellent protein to deficient diets. 



The assumed price of 1 cent per pound for 

 fish may not be valid, particularly for lean fish. 

 If the fish price were doubled to 2c' /lb, the costs 



Table 16. — Estimated fixed costs for the construction 

 of biological and press cake biological FPC plants. 



Process 



Biological 



Press cake 

 biological 



Capacity, tons 



of fish per day .... 200 



Feed to reactor Raw fish 



(fatty fish) 



Fixed costs: 



Equipment $1,783,257 



Spare parts 20,906 



Facilities 210,348 



Engineering 151,088 



Contingencies .... 216,560 



Total capital costs $2,382,159 



200 



Press cake 

 (fatty fish) 



$1,985,130 



26,250 



210,348 



166,630 



238,836 



$2,627,194 



26 



