The effect of algae growth on aerobic granulation and nutrients removal was studied in two identical sequencing batch reactors (SBRs). Sunlight exposure promoted the growth of algae in the SBR (Rs), forming an algal-bacterial symbiosis in aerobic granules. Compared to the control SBR (Rc), Rs had a slower granulation process with granules of loose structure and smaller particle size. Moreover, the specific oxygen uptake rate was significantly decreased for the granules from Rs with secretion of 25.7% and 22.5% less proteins and polysaccharides respectively in the extracellular polymeric substances. Although little impact was observed on chemical oxygen demand (COD) removal, algal-bacterial symbiosis deteriorated N and P removals, about 40.7-45.4% of total N and 44% of total P in Rs in contrast to 52.9-58.3% of TN and 90% of TP in Rc, respectively. In addition, the growth of algae altered the microbial community in Rs, especially unfavorable for Nitrospiraceae and Nitrosomonadaceae.

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By a post synthesis method, nickel (Ni) particles could be grafted onto SBA-15 for the first time through a chemical bond (-O-Ni-O-Si-O-) formation between silicon (Si) and Ni via oxygen (O) using Ni ammonia (NH3) complex ions (Ni(NH3)x) 2+ with NH3/Ni mole ratio of 1~5, which existed as Ni phyllosilicate on SBA-15 surface, while Ni particles could not be grafted onto SBA-15 in the absence of NH4OH (NH3/Ni mole ratio of 0). NH3/Ni mole ratio of 2~4 was suitable grafting conditions, which could give a product with the closest Ni amount to raw. This product obtained was named Ni-grafted SBA-15 sample. XPS, UV-vis and H2-TPR analyses demonstrated that a chemical bond was formed between Ni and silicon (Si) via oxygen (O), and no bulk nickel oxides existed in Ni-grafted SBA-15 sample. The formation of -O-Ni-O-Si-O-was completed via the reaction between hydrolyzate Ni(OH)(NH3)x-1) + from (Ni(NH3)x) 2+ and ≡Si-OH (silanol sites) on SBA-15 surface. Ni-grafted SBA-15 catalyst suited CO2 methanation, resulting in higher CO2 conversion and methane selectivity than NiO dispersed SBA-15 catalyst obtained by conventional post synthesis method. The activation energy for CO2 methanation increased with decreasing initial Ni amount used. The rate equation for CO2 methanation could be expressed as: r = kCCO 2 0.64 CH 2 4.05 , C was concentration. Ni-grafted SBA-15 catalyst had high thermal stability for CO2 methanation.

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