Biological Reclamation of Solid Wastes [antikvár]

INTRODUCTION Open dumping, burial, submersion in the ocean, incineration, and combinations thereof continue to be the conventional procedures for municipal solid waste disposal. Happily in the United States the open dump and disposal in the ocean are gradually being phased out. On the other hand, burial will always be a necessity to some extent, because every other method of treatment leaves a residue that can be disposed of only by burial in the land (landfilling). These methods have two things in common: no resources are recovered, and they are physical in nature. However, in the offing is a collection of physical, chemical, and biological methods of solid waste treatment that are designed for recovery of resources. The only biological method of solid waste treatment that has been developed beyond the pilot plant stage thus far is composting. But, until quite recently an unfortunate combination of circumstances has resulted in the failure of composting to be considered in the United States as a viable method of municipal solid waste treatment other than for park and garden debris and some agricultural wastes. The situation has been only slightly better in countries other than the United States. Aside from composting, biological systems with a potential for processing wastes on a large scale are the spreading of wastewater sludges on the land, anaerobic digestion, and hydrolysis of cellulosic wastes to sugars and subsequent production of single-cell protein or ethanol. A key feature common to these four systems is the recovery of one or more resources. However, of the four, only leuid spreading and composting hitherto have been applied on a scale not exceeding the small pilot plant.