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A normally operating treatment plant should have a pH of between 6.5 and 8.0. The <br /> bacteria responsible for the digestion of sludge cannot normally live and grow if the pH <br /> is not in the range. A pH reading outside this range indicates either (1) that the plant is <br /> septic; this can be corrected by the methods listed in the first section of the manual or <br /> (2) acidic or caustic wastes are entering the bio-plant-, these should be stopped before <br /> they enter the plant. <br /> IV. CHLORINE RESIDUAL TEST <br /> The principal reason for chlorination of sewage effluent is for disinfection. Sewage <br /> treatment may not completely remove the pathogenic (disease-causing) bacteria that <br /> may be present. The chlorine residual is measured by using a color comparator. <br /> When effluents are discharged to bodies of water which are, or may be used as a <br /> source of public water supply, or for recreational purposes, chlorination to kill harmful <br /> bacteria will require a chlorine residual of greater than 0.5 ppm. This residual must be <br /> the minimum maintained in the effluent. If the test results show less than this, increase <br /> the rate of chlorine feed. <br /> Observation & Testing <br /> Microscopic Examinations <br /> A microscope will prove valuable in waste treatment system operation, and we <br /> encourage use of this instrument by our field representatives, and by operators of larger <br /> systems. By examining a single drop of the mixed liquor (contents of the aeration <br /> chamber) with a microscope set at 100x magnification, the operator can quickly <br /> determine the condition of the floc (mixed liquor). <br /> Floc Characteristics <br /> (a) A normal, well operating system is indicated when the floc masses are small to <br /> medium density, with no scattered bacteria. <br /> (b) A toxic condition exists, or a sudden increase in organic loading has taken place, <br /> when the floc masses are small to medium density with many scattered bacteria, <br /> (c) A low oxygen concentration of low pH condition is indicated when filamentous <br /> (thin, thread-like) microorganisms are present. <br /> Types of Animals Present in Mixed Liguor <br /> Since the animals that are present in activated sludge systems also indicate the <br /> operating condition of the system, it is necessary that the person performing the <br /> pcs/o&n-observ&test 1-5 <br />