Study On Performance Of Improved Aerobic Granular Sludge By Nd

Aerobic granular sludge technology is a new type of biological wastewater treatment technology. The rare earth element Neodymium has the similar characteristics which calcium has and the biological effects that are common to all rare earth elements.The biological effect means that suitable concentration of rare earth element neodymium could promote promote the formation of granular sludge process and could improve the performance of granular sludge. This paper studied the culture and performance of granular sludge in two SBRs which were performed under the same operations. Improved aerobic granular sludge by Nd (Dd3+10mg/L) was cultived in SBR1while the common one was cultived in SBR2. The changes of different forms of extracellular polymeric substances and nitrification removal were also researched. Conclusions as follows:1、Mature improved aerobic granular sludge was gained after24days’ culture in SBR1while the common one grew mature after36days on the conditions that the chemical oxygen demand loading was1.75Kg/(m3·d), the nitrogen loading was0.36Kg/(m3·d), the concentration of Nd was10mg/L, the operation was fixed at4hours and the superficial gas velocity was1.09-1.31cm/s. The result suggests that the rare earth element Neodymium could speed up the process of granulation and improve the engineering efficiency.2、The result shows that in the granulation process, the improved granular sludge in SBR1growed faster than the common ones in SBR2. The value of SVI in SBR1was lower than that in SBR2, which means that the improved granular sludge had better settling property. The SOUR of granulars in SBR1was7.311mg/g min and the SOUR of granulars in SBR2was5.604mg/g min, so the improved granular sludge had better activity.3、The average partical size of mature sludge in SBR1and SBR2was2.5mm and1.6mm respectively, the value of IC was74.67%and88%respectively, the moisture content of sludge in SBR1and SBR2was91.8%and95.6%,the specific gravity was 1.0651for improved sludge in SBR1and1.0554for common sludge in SBR2.4、Comparing the calcium ion concentration in the effluent of the two systems during the modified stage, we found that the Ca2+concentration in the effluent of SBR1is lower than that of SBR2. It means that adding the rare earth element Neodymium in influent could lead to competition with calcium. The absorption and utilization of calcium were adverse effected because of Neodymium.5. Extracellular polymeric substances(EPS) include two kinds forms:EPS in the supernatant and EPS in sludge.For both the common granular sludge and improved granular sludge, there is more EPS in sludge than the EPS in the supernatant and the content of EPS in the supernatant is about only one-fifth of the content of EPS in sludge. The major component of EPS in the supernatant is polysaccharide while the major component of EPS in sludge is protein. Adding suitable concentration of Neodymium (10mg/L) could promote the content of polysaccharide of EPS in the supernatant obviously. On the contrary, the content of protein of EPS in sludge was increased significantly after adding Neodymium.6、The study on the performance of pollutant removal showed thatthe mature modified aerobic granular sludge has good pollutant removal efficiency of COD removal efficiency of93%and NH4+-N removal efficiency of92%. In the first1.5h of the complete cycle, the concentration of NH4+-N is drastically reduced, while the concentrations of NO3-N and NO2-N remained at a low level and the accumulation of nitrite was no found in a complete cycle. Simultaneous nitrification and denitrification appeared in SBR1system.