Belt Filter Press Dewatering Trials with Cambi Thermally Hydrolyzed Biosolids – Evaluation of Critical Performance Criteria

Abstract

A series of belt filter press trials were performed to assess BFP technology as a method for dewatering digested biosolids which had been pretreated by the Cambi Thermal Hydrolysis Process (THP). The THP is a sludge pretreatment process which heats raw sludges to high temperature (150-165 °C ) using steam followed by mesophilic digestion. In this study, two different full scale THP sludges were dewatered on two belt filter presses supplied by two different manufacturers. The digested THP sludges had solids concentrations between about 5-7%. The goal of the project was to evaluate the effect of solids loading rates and polymer dosing on cake solids and capture. The results showed the THP sludges dewatered well using BFPs, with cakes solids of 30% or higher easily achieved along with capture rates greater than 99%. This performance was achieved over a broad solids loading rate with 30% cake solids being achieved at loading rates of up to 1000 kg/m-hr. The study also showed that mixing of the polymer and sludge was a critical parameter for achieving good flocculation and dewatering. 672WEFTEC 2011

Assessment of lime‐conditioned dairy manure fine solids captured using dissolved air flotation for fertilization in horticulture

“…Total solids content increased with lime dosage, with the greatest moisture reduction achieved with the 6% quicklime and LKD treatments. A full‐scale dewatering study of anaerobically digested biosolids similarly reported achieving ∼30% cake total solids using a belt filter press, though some key operational parameters differed from the present study, most notably the lower feedstock total solids content (∼5–8% total solids) and the use of a polymer rather than lime to enhance dewatering (Fountain et al., 2012).…”

Thermal Hydrolysis Considerations for Pre-Digestion Solids Processing

“…Research and testing by a combined DC Water/Thames Water team in 2010 helped confirm the design and operating parameters when using BFPs for this service (Fountain et al, 2011). DC Water in its new facility in Washington DC will be using BFPs and is anticipating cake solids of about 30 percent.…”

“…Low-energy dewatering processes such as belt filter presses can achieve cakes of nearly 30 percent solids or even higher than 30 percent solids (Fountain et al, 2011). Digested solids that are high in WAS feed percentage will show the most advantage in post-digestion dewatering because of the impact of TH on the WAS feedstock.…”