Sulfur-based autotrophic denitrification with eggshell for nitrate-contaminated synthetic groundwater treatment

• Published in: Environmental technology Vol. 37; no. 24; pp. 3094 - 3103
• Main Authors: Xu, Yaxian, Chen, Nan, Feng, Chuanping, Hao, Chunbo, Peng, Tong
• Format: Journal Article
• Language: English
• Published: England Taylor & Francis 16.12.2016; Taylor & Francis Ltd
• Subjects: Ammonium Compounds - metabolism; Animals; autotrophic denitrification; Denitrification; Egg Shell - chemistry; eggshell; Feasibility studies; Groundwater; Groundwater - chemistry; Groundwater treatment; Hydrogen-Ion Concentration; nitrate reduction; Nitrate removal; Nitrates; Nitrates - chemistry; Nitrites - metabolism; Sewage - microbiology; Sulfates; Sulfates - metabolism; Sulfur; Sulfur - metabolism; synthetic groundwater; Temperature; Wastes; Water Pollutants, Chemical - chemistry; Water Purification - methods; British Isles; nitrate reduction; eggshell; Sulfur; autotrophic denitrification; synthetic groundwater
• ISSN: 0959-3330; 1479-487X
• DOI: 10.1080/09593330.2016.1176077

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.