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malodors." Pasteurization, ionizing radiation, and heat treatment can elim- 

 inate pathogens, but leave the sludge in an unstabilized state — it will 

 quickly putrify when applied to land. 



Current research indicates that the health hazard from pathogens is 

 minimal. Tests using indicator viruses have shown excellent pathogen kill, 

 even though higher temperatures are needed to kill the indicator organism 

 than to kill organisms responsible for the diseases of concern to man. 

 Negligible numbers of salmonellae and undec table fecal coliforms remained 

 after the composting period (Epstein and Willson, 1975). 



These results have been borne out in Durham. Sampling conducted in 

 1975, for example, showed no measurable numbers of Salmonella sp. in fully 

 composted sludge. Despite the apparent lack of pathogenicity of the compost, 

 its use on food crops, particularly root crops, is not recommended. To 

 avoid any possibility of legal repercussions, town personnel should have a 

 firm and consistent policy of recommending the use of compost only on turf 

 and ornamentals. 



SUMMARY 



The sludge composting process developed at Beltsville, Maryland, and 

 presently in use by the Town of Durham has proven desirable from a number 

 of standpoints. The process results in a useable, stable product with 

 little odor problem and excellent pathogen kill. In addition, the cost is 

 competitive with other methods. Total fixed costs to start the Durham pro- 

 ject were $899. Total costs for operating equipment were $224 (excludes 

 equipment already owned by the town for other purposes) . Composting costs 

 for the first few piles were $912. This works out to approximately $72 per 



