Dewatering Study

The Applied Technology Group of KEMRON Environmental Services, Inc. (KEMRON) conducted a dewatering laboratory bench scale study on impacted sediment from a river site located in the Boston, Massachusetts area. The purpose of the dewatering study was to evaluate dewatering techniques in order to increase the material percent solids and density for potential disposal.  Four site sediments were evaluated during the bench scale study.  The sediments showed a variation in particle size distribution from coarse sand to silt and was impacted with Hexavalent Chromium. KEMRON evaluated the effectiveness on the site materials for three different dewatering techniques including Recessed Plate Simulations through the use of Baroid filter press testing, Belt Filter dewatering using a Crown® Belt Filter Press, and GeoTube® dewatering through the use of the GeoTube® Rapid Dewatering Technique (RDT).  The study included polymer evaluations as well as evaluating the dewatering technology on the “as received” material and material screened through a #200 sieve (de-sanded). Results of the Recessed Plate simulations indicated each pressure used during the study was effective in increasing the percent solids up to 72% as well as reducing total suspended solids and Hexavalent Chromium concentrations in the effluent. Testing using the Crown Belt Filter Press with several different belt fabrics resulted in increasing the percent solids up to 78% as well as reducing total suspended solids and Hexavalent Chromium concentrations in the effluent. KEMRON performed GeoTube® RDT (on both the desanded and non-desanded site materials. After the initial evaluation of both types of materials, it was determined that desanding would not be necessary should GeoTube® technology be used. Results of the RDT showed a greater increase in percent solids with the non-desanded material than with the desanded material. Effluent evaluations from the RDT showed the highest levels of total suspended solids compared to other dewatering technologies. However, Hexavalent Chromium levels were determined to be non-detect for each of the four site materials.