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| Nutrient removal from piggery digestate using a microalgae-bacteria system and its influencing conditions |
| Received:March 09, 2018 |
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| KeyWord:microalgae-bacteria system;piggery digestate;photosynthetic oxygen production;nitrogen and phosphorus;organic pollutant |
| Author Name | Affiliation | E-mail | | LUO Long-zao | School of Chemistry and Environmental Science, Shangrao Normal University, Shangrao 334001, China
College of Environmental and Resources Sciences, Zhejiang University, Hangzhou 310058, China | | | ZENG Fan-jian | College of Environmental and Resources Sciences, Zhejiang University, Hangzhou 310058, China | | | TIAN Guang-ming | College of Environmental and Resources Sciences, Zhejiang University, Hangzhou 310058, China | gmtian@zju.edu.cn |
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| Abstract: |
| Owing to the high concentrations of nitrogen and phosphorus and the imbalance in the C/N ratio in piggery digestate, it is difficult to treat this wastewater based on traditional biochemical processes. Desmodesmus sp. CHX1 and agent bacteria with high-efficiency organic pollutant removal were used in this study to develop a microalgae-bacteria system that effectively treats piggery digestate. The aim was to investigate the effects of temperature and light on the purification of piggery digestate in the microalgae-bacteria system. The results showed that the addition of organic pollutant degradation bacteria not only improved the growth of Desmodesmus sp. CHXl(the biomass increased by 23.53%), but also increased TOC(total organic carbon), NH4-N(ammonium nitrogen), and TP(total phosphorus) removals by 13.40%, 3.39%, and 5.90%, respectively, during piggery digestate treatment. Temperature was an important factor in nutrient(TOC, NH4+-N, and TP) removal. A temperature of 30℃ was the best condition for the highest microalgae growth rate and TOC and TP removal rates. The biomass of microalgae reached 2.21 g·L-1, and the removal efficiencies of TOC and TP were 72.64% and 26.66%, respectively. The best condition for NH4+-N removal was 40℃, which possibly enhanced NH4+-N volatilization. Light radiation intensity was another key factor for purifying wastewater using the microalgae-bacteria system. By increasing the light intensity, the microalgae growth rate and photosynthetic oxygen production obviously increased, and the TOC, NH4+-N, and TP removal efficiencies improved significantly. However, the growth rate and removal efficiency did not increase when the light intensity ranged from 400 μmol·m-2·s-1 to 600 μmol·m-2·s-1. The highest microalgal biomass and pollutant removal were observed under 400 μmol·m-2·s-1 light intensity, leading to the highest microalgae biomass of 2.35 g·L-1 and the highest removal efficiencies of 57.03%, 68.01%, and 59.66% removal for TOC, NH4+-N, and TP, respectively. |
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