GB435380A - Treatment of organic waste - Google Patents

Abstract

In treating solid or semi-solid putrefiable organic waste by inoculating the material with thermophile aerobic bacteria derived from the soil, which then effect its decomposition, the organic waste may be inoculated with a "starter" prepared by incubating a moist mixture of fertile soil, peat humus, ground up common garbage, cane molasses, wood ashes, marl or ground calcium carbonate, and gypsum at a temperature not exceeding 180 DEG F. If desired, pure cultures may be isolated from this starter by standard methods employing a dextrose agar medium, containing hard wood ashes and incubating at 37-50 DEG C., say for twenty-four hours.ALSO:Manures &c. are obtained from solid or semi-solid putrefiable organic waste by inoculating the material with thermophile aerobic bacteria derived from soil to effect its decomposition, aerating and agitating the inoculated material and controlling its temperature by retaining the heat developed during the decomposition so as to maintain a temperature suitable for the development of the bacteria. Temperatures of 100-180 DEG F. are suitable. Garbage, sewage sludge, sewage screenings, organic trade waste, &c. may be treated. The organic material may be admixed with a neutral salt of a weak acid, e.g. calcium carbonate, to control the acidity or a culture medium comprising peat humus, gypsum and calcium carbonate. Preferably, the organic waste is comminuted and excess water is squeezed therefrom prior to the decomposition process. The decomposition may be effected in a digesting apparatus consisting of a number of superimposed decks in conjunction with slowly rotating ploughs or rakes which gradually move the material to a lower deck. The inoculated material, preferably having a moisture content between 50 and 90 per cent, is fed to the upper deck where a temperature of 110-120 DEG F. prevails. It gradually falls and at the sixth deck which it reaches in 24-36 hours a temperature of 180 DEG F. or more prevails. A draft is permitted through the apparatus and each deck is provided with ventilating means, or a single ventilator for the whole apparatus may be provided. The material leaving the digester has a moisture content of about 30 per cent and may be used as such or may be further treated, say by drying to 220-250 DEG F. or by admixture, with or without drying, with other fertilizers such as calcium acid phosphate, potassium sulphate or chloride, ammonium salts such as ammonium sulphate or nitrates such as sodium nitrate. If an inoculated mixed fertilizer is being prepared, raw fertilizing materials such as ground phosphate rock, leucite, &c. may be employed as additions. Sulphur may also be used. Nitrogen bacteria and soil bacteria may also be mixed with the fermented product. The inoculation may be effected with pure cultures of aerobic thermophile bacteria derived from the soil or by means of a "starter" prepared by incubating a moist mixture of fertile soil, peat humus, ground-up common garbage, cane molasses, wood ashes, marl or ground calcium carbonate, and gypsum at a temperature not exceeding 180 DEG F. If desired, pure cultures may be isolated from this "starter" by standard methods employing a dextrose agar medium containing hard wood ashes and incubating at 37-50 DEG C., say for 24 hours.