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In 1997, the City selected Boyle Engineering Corporation (Boyle) to investigate treatmentmethods to reduce the color and the hydrogen sulfide in the water from Well 37. In addition,arsenic reduction treatment was desired if possible. Based on previous pilot testing of Hanford'swater for arsenic reduction using oxidation, precipitation, and a proprietary filtration process, apilot program utilizing two manufacturers (Filtronics, Inc. and Pureflow Filtration Division) wasrecommended.The proprietary filtration process (PFP) utilizes a proprietary multimedia within an enclosedpressure vessel. In general, raw water is pretreated in a reaction vessel using chlorine, sodiumbisulfite, and possibly ferric chloride prior to filtration. In these treatment systems iron,manganese, hydrogen sulfide, and arsenic are oxidized. The hydrogen sulfide is oxidized tosulfate. The iron and manganese are precipitated as hydroxides, adsorbing the arsenic. Theaddition of ferric chloride assists in further reducing the arsenic. The arsenic is removed in themedia-filled pressure vessel as an iron/arsenic or manganese/arsenic precipitate. The filter mediarequires no regeneration but must be backwashed periodically like a conventional sand filter.The backwash water is directed to a settling tank where the backwash water can be decanted andrecycled to the head of the plant. The resulting sludge (and sometimes the entire backwashwater) can be disposed of to a sewer or to on-site sludge-drying beds.Multiple pilot tests were performed at Well 37 by both Filtronics and Pureflow during 1997 and1998. The purpose of these tests was to demonstrate the treatment capabilities to meet two-phasedtreatment objectives. The two-phased treatment objective unique to Hanford'soperational goals, water quality standard compliance, and budget is discussed in this paper. Includes tables, figures.

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Edition: Vol. - No. Published: 06/15/2003 Number of Pages: 17File Size: 1 file , 370 KB