Abstract
This work was carried out to investigate waste water contamination caused by preparing for and doing dishes of two kinds of school lunch, A and B, which are deep fried dish and boiled dish. The study dealt with 1, 825 meals in five days. The average amount of waste water was 13.9 liter/meal, and in this respect there was no difference between A and B lunches. The most abundant water was used between 2 : 00 and 4 : 00 p. m. when dish-washing was done. SS, COD, BOD and TOD in the waste water were measured by standard methods set forth by JIS (K 0102) for the examination of industrial waste water. The results were as follows (range of amount obtained in five days and average value are shown in ppm).
SS : 6-452, 145; COD : 40-1, 038, 285; BOD : 57-1, 572, 483; TOD : 43-1, 940, 612.
These data were larger than the permissible value for public waste water. There was a difference in contamination of the waste water between A and B lunches; the respective averages of SS, COD, BOD and TOD for A lunch were larger than those for B. From these results it should be noted that egg, powder and mayonnaise are highly contaminative and much of them are used in A.
