Aeration-Induced Changes in Liquid Digested Sewage Sludge
1971
Molina, J. A. E. | Braids, O. C. | Hinesly, T. D. | Cropper, J. B.
Disposal of sludges produced by municipal sewage treatment plants is becoming an acute problem. Anaerobic fermentation of raw sludges gives rise to material referred to as digested sludge which is rich in nitrogen and phosphorus. Because it contains these nutrients, disposal of digested sludge on agricultural fields could be propitious to agriculture. Upon contact with air, the pH of the digested sludge rose to about 8.6 and its ammonium content was halved following ammonia losses. The digested sludge organic matter was not amenable to rapid biodegradation. Aeration of digested sludge does not cause any appreciable solubilization of its metal content. Corn (Zea mays L.) and soybean (Glycine max L.) seeds did not germinate in the liquid phase of fresh digested sludge. This inhibition was not due to ammonium nor solely caused by the salt concentration, the oxygen deficiency, or the low oxidationreduction potential of the medium. The seeds germinated in digested sludge which had been left in contact with the air for a few days.
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