Grit from grit traps in wastewater treatment plants, as well as grit from sewer and road cleaning, is heavily contaminated with organic matter and debris. The high organic content, with volatile solids ranging from 10% to 80%, is the primary reason these grit slurries do not dewater efficiently. As a result, the solids concentration remains inconsistent and challenging to manage.
The common performance criteria for the quality of grit removal are: The capture rate of 0.2 mm diameter grit particles; and the volatile solids concentration of the removed grit.
The end product of effective grit treatment is a reusable material with a volatile solids ratio of less than 3% and a water content of under 10%.
Such grit treatment not only reduces the volume and mass of the removed grit, but also the disposal costs. If the clean grit product is reused, e.g. for road bedding, costs for grit disposal could be avoided.
