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Phosphate-solubilizing fungi have been successfully applied to the release of phosphorus from insoluble tricalcium phosphate. A phosphate-solubilizing fungi Penicillium aurantiogriseum was isolated and investigated the phosphorus solubilizing capacity under different carbon and nitrogen resources. The highest released phosphorus content reached 1000 mg/L in ammonium and sucrose conditions. Carbon resources did not limit the release of phosphorus by Penicillium aurantiogriseum. However, nitrate and urea significantly reduced the phosphorus release, which had a low phosphorus content (~780 mg/L). Glucose and ammonium were more efficient for fungal growth and organic acid secretion. Oxalic acid secreted by Penicillium aurantiogriseum dominated the release of phosphorus. The formed calcium oxalate promoted the dissolution of tricalcium phosphate. This study indicated that the effective utilization of Penicillium aurantiogriseum to dissolve tricalcium phosphate need to support more ammonium nitrogen.

Aspergillus niger (A. niger) and Penicillium chrysogenum (P. chrysogenum) can significantly promote the degradation of maize straw and phosphorus release. Compared with P. chrysogenum, A. niger is more efficient in maize straw degradation and phosphorus releasing. After seven days of incubation, the highest degradation ratio and phosphorus content in A. niger+maize straw treatment is 2.58% and 2.3 mg/L, respectively. The mechanisms for maize straw decomposition between these two fungi are different. Oxalic acid is the primary organic acid secreted by A. niger, which is more function in the decomposition of maize straw compared with propionic acid secreted by P. chrysogenum. In addition, A. niger has higher acidic xylanase and lignin peroxidase enzymes activities, which is conducive to the degradation of more stable substances in maize straw, i.e., lignin. This study indicated that A. niger is the primary candidate for the reuse of crop straw in the way of return to the field.

Efficiency and mechanism of nitrogen removals by ecological concrete-based ecological systems (ECBESs) were investigated in this study. Results show that ECBES performed well on denitrification. Ecological concrete as matrix of the ecological was positive for nitrogen removing according to that the experimental ECBESs achieved a greater TN removal compared to the control system. This result was possibly attributable to a higher biomass and increased bacteria diversity in ECBESs, since ecological concrete could be a carrier of microorganism. Vegetation could further improve TN removals. Acorus calamus L. - ECBES, Ipomoea aquatica Forsk - ECBESs, Oenanthe javanica (Bl.) DC. - ECBES and Zizania aquatica - ECBES achieved an average TN removal of 67.87%, 81.93%, 76.18%, 66.22%, respectively, in a test cycle. Nitrogen transformation in the ECBESs indicated the occurrence of ammonification, nitrification and denitrification. Moreover, bacteria related to nitrogen transformation was identified from the bio-film immobilized on the ecological concrete.