Brown and Caldwell Home Page
Technical Papers RECENT PAPERS    ALL PAPERS

Brown and Caldwell engineers and scientists are technical and thought leaders in the environmental sector. Meet the people who have been advancing innovation for more than 70 years.
Author      Title/Abstract      


Predesign Evaluation of Biosolids Thickening Methods
Author: Kenneth D. Fonda, David Parry
Date: 9/292
Presented at WEF 65th Annual Conference, New Orleans, Louisiana, September 20-24,1992

Co-thickening of primary and waste activated biosolids (WAS) using dissolved air flotation (DAF) thickeners was chosen for the biosolids processing facilities (BPF) for the City of San Diego Clean Water Program. Selection of the process was based on an evaluation that compared separate to combined thickening of primary biosolids and WAS. The northern and southern BPF will receive an estimated 239 dry metric tons/day (266 dry tons/day) of raw biosolids. Data from other plants were collected to confirm operating performance as well as design criteria. It appears that primary solids assist the WAS in floating probably because of their larger particle size and material strength. A parametric analysis identified several key factors that influenced selection including biosolids characteristics, influent peaking factors, solids loading rate, energy and polymer usage, land and labor costs. The results of this evaluation showed that co-thickening with DAF thickeners had the lowest life cycle costs (LCC) when solids loading rates were relatively high. Co-thickening also had the lowest LCC for all polymer dosage rates evaluated. Separate thickening had the lowest LCC when additional costs were added for larger primary sedimentation tanks and digesters. This evaluation will be beneficial to engineers evaluation thickening methods by identifying the key parameters that determine the cost of constructing and operating thickening facilities.

This library contains published materials for which copyrights may be owned by entities other than Brown and Caldwell, but which are stored for limited uses by BC employees. Technical papers authored by BC employees generally may be printed and shared electronically with clients and prospective clients outside BC. Technical papers cannot be sold, and technical papers shared outside BC must have proper attribution of the original sponsoring organization or conference where the paper was presented. This attribution is embedded in each technical paper file when it is loaded into this library. Published articles from magazines or trade journals which are stored in this library are FOR INTERNAL USE ONLY and SHOULD NOT be distributed to clients or others outside BC, without express permission of the copyright owner. For questions regarding copyrights associated with any document in this library, or questions regarding copyrights in general, contact the Legal Department.