FISHERY BULLETIN: VOL. 75, NO. 2 



1. Heat 100-ml Pyrex beakers at 500°C for 1 h, air 

 cool for 1 h, and weigh. Prior to use, new 

 beakers should be equilibrated to ashing condi- 

 tions. 



2. Accurately weigh about an 80-ml sample of 

 effluent into the dry beaker. Dry overnight at 

 103°C in a forced draft oven and weigh after 1 h 

 of air cooling. 



3. Calculate TR in milligrams/liter. (Note: this 

 system, of course, gives TR in milligrams/1,000 

 g, but we follow the convention and express it 

 in milligrams/liter.) 



4. Heat beaker and dried sample at 500°C for 2 h, 

 air cool 1 h, and weigh as before. 



5. Calculate ash from the initial weight of 

 sample, express as milligrams/liter as in step 3. 



RESULTS 



In general, these effluent samples were tested 

 for COD, residue, ash, O&G, and protein. The data 

 in Table 1 are averages of duplicate analyses, ex- 

 cept O&G which is in triplicate. The data should 

 not be considered representative of the effluent 

 from this plant because of the specific way of tak- 

 ing these grab samples. Comparisons in relative 

 data, however, can be made. For example, the 

 COD of the filterable residue (COD FR ) was slightly 

 over one-half of the total COD (COD TR ) and the 

 filterable residue (FR) was 64% of the total residue 

 (TR) on an ash-free basis. The TR contained 17% 

 ash, but most of the ash was found in the FR frac- 

 tion (92%) leaving only 8% in the nonfilterable 

 residue (NFR) fraction. 



The relationship between COD and ash-free 

 residue is plotted in Figure 1 and that for O&G 



2800  



2 400 • 



\ 



2000 



o 

 z 

 < 



UJ 



q 1600 • 



> 



o 



< 



s 



UJ 



I 

 u 



200- 



800  



4 00 



COD TR = 1.41 TR K 



COD FR = 1.39 FR ( 



COD NFR = 1.69 NFR K + 10 



400 800 1200 1600 2000 



RESIDUE , mg/l 



FIGURE 1. — Relationship between the COD and the concentra- 

 tion of the ash-free residue in waste effluents from a plant using 

 both Model A and PCA peelers and fresh water. 



and protein versus ash-free residue is given in Fig- 

 ure 2. The coefficients of correlation were 0.99 and 

 0.97 for the COD regressions on TR K and FR K , 

 respectively. The F-test for linearity at the 95% 

 level of significance was 0.015 for the TR K line and 



TABLE 1. — Analyses of screened shrimp waste effluents from a plant using both Model A and PCA 

 mechanical peelers. [All values in milligrams/liter.] 



254 



