Grinding Pulping and Homogenization

Grinding Pulping and Homogenization

	Grinding Pulphing and Homogenization - For effective composting the substrates should be a finely divided granular material, which permits aeration, mixing and invasion by the degradative microorganisms. Particles of size about 47cm will be suitable and this can be achieved by grinding or shredding. Alternatively, wet pulping method can also be used which produces a slurry containing about 5% solids. But this requires drying to about 50% solids to be suitable for composting. Sometimes agitation in the initial stages of compo sting causes the break down of fibres in the material to be composted. This reduces the pretreatment required.
A moisture level of about 40 to 50% is ideal for good composting. Low moisture content may inhibit microbial action. So, at this stage moisture content has to be adjusted. The required moisture content can be attained by adding water. Sewage sludge can also be used to attain required moisture and in this case the final product will be of a higher grade. The sludge may be raw, dewatered, digested or a combination of these types and the nature of resulting compost will depend on the sludge used. Generally raw primary or secondary sludge will be preferred to digested sludge because they can be easily dewatered and has a higher nutrient content. When municipal refuse and sewage sludge are combined for composting, the ratio of refuse to sludge should be approximately 2: 1 by weight.