hygiene also has economic benefits (reduced working time). The more fully the sludge is digested, the more pathogens are killed. High temperatures and long retention times are more hygienic. The availability of biogas can have effects on nutritional patterns too. With easy access to energy, the number of warm meals may increase. Whole grain and beans may be cooked longer, increasing their digestibility, especially for children. Water may be boiled more regularly, thus reducing waterborne diseases. Biogas plants also improve health conditions in the homes: Since biogas burns clean, homes do not fill with smoke and ash. Women and children experience less bronchial problems and can expect to live longer. Homes are also more hygienic. Dung cakes are no longer stored in the homes. Cooking with gas takes less time than with wood or charcoal or any other commonly used fuel. It is easier to cook with gas stove. Economical
brane, with no invasion of the bloodstream and ribotyping by Qualicon system, and 490 Chapter 28 others are finding their ways into food micro- nineteenth century and early twentieth biology laboratories. century. The organism is under control in Because Salmonella is heat sensitive, many industrialized countries; however, it is proper cooking will destroy the organism. still a very important waterborne disease in Also, proper chilling, refrigeration, and good places with poor sanitary conditions. The sanitation will minimize the problem. classical work of John Snow in 1854 showed Salmonella remains one of the most impor- the transmission of V. cholerae through tant food pathogens in our food supply. poorly designed water-delivery systems in London. His work led to the development of
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