title: Sulfur-based autotrophic denitrification with eggshell for nitrate-contaminated synthetic groundwater treatment.
abstract: Eggshell is considered to be a waste and a significant quantity of eggshell waste is generated from food processing, baking and hatching industries. In this study, the effect of different sulfur/eggshell (w/w) ratios and temperatures was investigated to evaluate the feasibility of the sulfur-based autotrophic denitrification with eggshell (SADE) process for nitrate removal. The results showed eggshell can maintain a neutral condition in a range of pH 7.05-7.74 in the SADE process, and remove 97% of nitrate in synthetic groundwater. Compared with oyster shell and limestone, eggshell was found to be a desirable alkaline material for sulfur-based autotrophic denitrification (SAD) with no nitrite accumulation and insignificant sulfate production. Denitrification reaction was found to follow the first-order kinetic models (R(2) > .9) having nitrate removal rate constants of 0.85 and 0.93 d(-1) for raw eggshell and boiled eggshell, respectively. Sulfur/eggshell ratio of 2:3 provided the best efficiency on nitrate removal. Nitrate was removed completely by the SADE process at a low temperature of 15°C. Eggshell could be used for the SAD process due to its good effect for nitrate removal from groundwater.
authors.affiliation: a School of Water Resources and Environment , China University of Geosciences , Beijing , People's Republic of China.|b Ministry of Education, Key Laboratory of Groundwater Cycle and Environment Evolution , China University of Geosciences , Beijing , People's Republic of China.
authors.forename: Yaxian
authors.initials: Y
authors.lastname: Xu
authors.affiliation: a School of Water Resources and Environment , China University of Geosciences , Beijing , People's Republic of China.|b Ministry of Education, Key Laboratory of Groundwater Cycle and Environment Evolution , China University of Geosciences , Beijing , People's Republic of China.
authors.forename: Nan
authors.initials: N
authors.lastname: Chen
authors.affiliation: a School of Water Resources and Environment , China University of Geosciences , Beijing , People's Republic of China.|b Ministry of Education, Key Laboratory of Groundwater Cycle and Environment Evolution , China University of Geosciences , Beijing , People's Republic of China.
authors.forename: Chuanping
authors.initials: C
authors.lastname: Feng
authors.affiliation: b Ministry of Education, Key Laboratory of Groundwater Cycle and Environment Evolution , China University of Geosciences , Beijing , People's Republic of China.
authors.forename: Chunbo
authors.initials: C
authors.lastname: Hao
authors.affiliation: b Ministry of Education, Key Laboratory of Groundwater Cycle and Environment Evolution , China University of Geosciences , Beijing , People's Republic of China.
authors.forename: Tong
authors.initials: T
authors.lastname: Peng
mesh_terms: D064751:Ammonium Compounds / Q000378:metabolism; D000818:Animals; D058440:Denitrification; D004528:Egg Shell / Q000737:chemistry*; D060587:Groundwater / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D009566:Nitrates / Q000737:chemistry*; D009573:Nitrites / Q000378:metabolism; D012722:Sewage / Q000382:microbiology; D013431:Sulfates / Q000378:metabolism; D013455:Sulfur / Q000378:metabolism*; D013696:Temperature; D014874:Water Pollutants, Chemical / Q000737:chemistry*; D018508:Water Purification / Q000379:methods*
chemical_list: D064751:Ammonium Compounds; D009566:Nitrates; D009573:Nitrites; D012722:Sewage; D013431:Sulfates; D014874:Water Pollutants, Chemical; D013455:Sulfur
keywords: Sulfur; autotrophic denitrification; eggshell; nitrate reduction; synthetic groundwater