| |
| |
Caption: SWE - Proceedings of the First International Conference of Women Engineers and Scientists
This is a reduced-resolution page image for fast online browsing.
EXTRACTED TEXT FROM PAGE:
Table 2 WHO Recommendation for Maximum Allowable Amounts of Toxic Materials in Waste Waters Entering Water Systems Substance Water with Biological Clarification 6.5 - 8.5 upper limit fixed separately should not be conducted 20 1 1 none 500 0.5 none 1 - Running Water System 6.5 - 8.5 10 to 30 pH value no limits 5 1 1 0.2 800 0.5 none 0.1 0.1 2 0.2 0.5 0.5 none 1 5 25 Acidity, pH-value Insoluble solid residue, ppm Aluminium Ammonia, ppm Lead, ppm Cadmium, ppm Chlorine, ppm Chloride, ppm Chromium II, ppm Chromium IV Cyanide, ppm Iron, ppm Fluoride, ppm Copper, ppm Nickel, ppm Nitric, ppm Suphate, ppm Suphite, ppm Zinc, ppm Q Temperature C 2 0.2 0.5 20 200 20 5 35 Though the protection of natural water entails strict prohibitions and restrictions as a matter of values which must be preserved, the general objective of protecting water systems can not be so absolute that all other interests must be subordinated. With close cooperation between groups working for the improvement of public health and those who aim at improvement in the process of production, it is possible to achieve satisfactory results. With certain limits, prevention of the effects of pollutants is practicable by purification of the water to be utilized. In the treatment of both household water and water for industrial purposes, the same methods are in general used. The most important of these are aeration, clarification, filtration, coagulation by either chemical or biological means, disinfection and chemical balancing. One or several of these individual operations may be used in the purification of water. Iron and manganese, 111-44
| |
