Performance Evaluation of Existing Wedgewater and Vacuum-Assisted Bed DewateringSystems

摘要

Many Army wastewater treatment plants (WWTPs) use conventional sand drying bedsto dewater sludge. However, sand-drying is slow, and requires a large land area commitment and manual sludge removal. Outdoor sand-drying beds are vulnerable to weather conditions and operational problems associated with sand-media and underdrain clogging. Successful new technologies for sludge treatment in small-scale WWTPs include wedgewater beds (WBs), vacuum-assisted beds (VABs) and reed-bed systems. As operator of over 100 small WWTPs, the Army has an interest in such cost effective and technically efficient sludge-dewatering systems. This study compiled operational data from commercial WWTPs with existing WBs and VABs to evaluate their potential for Army use. Generally. WBs were found to be easier to operate and maintain than VABs. WBs also showed fewer media-and underdrain-clogging problems when high-pressure hoses were used to clean the media, and when tiles were kept free from damage. VABs were preferred by smaller plants that required a lower target solids rate. Most problems with both systems were associated with poor media cleaning, front-end loader damage, and engineering errors.