Performance of a pilot‐scale packed bed reactor for perchlorate reduction using a sulfur oxidizing bacterial consortium

Abstract

A novel sulfur-utilizing perchlorate reducing bacterial consortium successfully treated perchlorate (ClO₄⁻) in prior batch and bench-scale packed bed reactor (PBR) studies. This study examined the scale up of this process for treatment of water from a ClO ₄⁻ and RDX contaminated aquifer in Cape Cod Massachusetts. A pilot-scale upflow PBR (∼250-L) was constructed with elemental sulfur and crushed oyster shell packing media. The reactor was inoculated with sulfur oxidizing ClO₄⁻ reducing cultures enriched from a wastewater seed. Sodium sulfite provided a good method of dissolved oxygen removal in batch cultures, but was found to promote the growth of bacteria that carry out sulfur disproportionation and sulfate reduction, which inhibited ClO₄⁻ reduction in the pilot system. After terminating sulfite addition, the PBR successfully removed 96% of the influent ClO₄⁻ in the groundwater at an empty bed contact time (EBCT) of 12 h (effluent ClO₄⁻ of 4.2 µg L(-1)). Simultaneous ClO₄⁻ and NO₃⁻ reduction was observed in the lower half of the reactor before reactions shifted to sulfur disproportionation and sulfate reduction. Analyses of water quality profiles were supported by molecular analysis, which showed distinct groupings of ClO₄⁻ and NO₃⁻ degrading organisms at the inlet of the PBR, while sulfur disproportionation was the primary biological process occurring in the top potion of the reactor.

Sulfur-based autotrophic denitrification of drinking water using a membrane bioreactor

“…However, high operational costs, low selectivity and the formation of secondary brine wastes after treatment are the disadvantages of these processes. In recent years, biological denitrification has been considered as an alternative process for nitrate removal from drinking water [3][4][5][6][7].…”

Autotrophic perchlorate reduction kinetics of a microbial consortium using elemental sulfur as an electron donor

“…The S 0 pellets as the electron donor can eliminate the issues associated with organic residuals, provide a slowly released supply of electron on demand, offer lower expense cost as well as lower maintenance cost, and produce little excess biomass. Batch experiments and packed-bed reactors utilizing S 0 as the electron donor have been proven to be efficient for perchlorate reduction (Boles et al 2012;Ju et al 2007;Sahu et al 2009). As we all know, the kinetic parameters of microbial perchlorate reduction are essential to design biological treatment systems, as well as to predict and evaluate their performance.…”

Simultaneous removal of perchlorate and nitrate in a combined reactor of sulfur autotrophy and electrochemical hydrogen autotrophy

“…Although H 2 is a good energy substrate for ClO 4 À and NO 3 À reduction, it is difficult to handle in bulk quantities and is publicly perceived to represent a significant disaster threat due to its inherent explosive nature. Granular sulfur (S 0 ) in packed bed bioreactors has been successfully used as an electron donor in the autotrophic reduction of ClO 4 À and NO 3 À [20, [23][24][25][26]. As granular S 0 is insoluble in water, it can provide a slow-release supply of electron on demand and offer low expense cost as well as low maintenance cost.…”