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The State of California Department of Health Services (DHS) has developed draft regulations addressinggroundwater recharge with reclaimed water. In recognition of the need to remove, or reduce theconcentrations of health-significant organic constituents that may be present in municipal wastewater,DHS has selected total organic carbon (TOC) as a parameter to be monitored in the reclaimed water. Theintent of the TOC requirement is to limit the TOC of wastewater origin in the extracted water to amaximum of 1 mg/L. Dilution, either at the point of recharge or in the aquifer, is also required to limitthe maximum reclaimed water contribution to 50% unless methodology is identified and demonstrated tobe as effective as a 1:1 dilution. Two questions central to the dilution requirement issue are explored inthis paper. Can reclaimed water having less than or equal to 1 mg/L TOC be reliably produced? Does meeting a TOC limitof less than or equal to 1 mg/L in the reclaimed water at the point of recharge provide a level of health protection equivalentto meeting a TOC limit of less than or equal to 2 mg/L in the reclaimed water and blending it 1:1 with water of non-wastewaterorigin? The purpose of this paper is not to advocate elimination of the dilution requirement in the draftgroundwater recharge regulations for reclaimed water used for indirect potable reuse. The intent is tosuggest addition of an alternative method of treatment that could be included in the regulations toproduce reclaimed water that, from a health standpoint, is at least equivalent to blended water having thesame TOC concentration of wastewater origin. Includes 43 references, tables.

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Edition: Vol. - No. Published: 01/01/2000 Number of Pages: 19File Size: 1 file , 250 KB