Insight into microbial adaptability in continuous flow anaerobic ammonium oxidation process for low-strength sewage treatment.

Organic matter concentration is a critical factor influencing the adaptability of anaerobic ammonium oxidation (anammox) bacteria to low-strength sewage treatment. To address this challenge and achieve stable anammox activity, a micro-aeration partial nitrification-anammox process was developed for continuous-flow municipal sewage treatment. Under limited ammonium conditions, the effective utilization of organics in denitrification promoted the stable accumulation of nitrite and enhanced anammox activity. This, in turn, led to enhanced nitrogen removal efficiency, reaching approximately 87.7%. During the start-up phase, the protein content of extracellular polymeric substances (EPS) increased. This enhanced EPS intensified the inhibitory effect of denitrifying bacteria (DNB) on nitrite-oxidizing bacteria through competition for nitrite, thereby facilitating the proliferation of anammox bacteria (AnAOB). Additionally, several types of DNB capable of utilizing slowly biodegradable organics contributed to the adaptability of AnAOB. These findings provide valuable insights for ensuring efficient anammox performance and robust nitrogen removal in the treatment of low-strength sewage.

Preliminary Study of Preheated Decarburized Activated Coal Gangue-Based Cemented Paste Backfill Material.

This study proposes a novel idea of the use of coal gangue (CG) activation and preheated decarburized activated coal CG-based cemented paste backfill material (PCCPB) to realize green mining. PCCPB was prepared with preheated decarburized coal CG (PCG), FA, activator, low-dose cement, and water. This idea realized scale disposal and resource utilization of coal CG solid waste. Decarbonization and activation of CG crushed the material to less than 8 mm by preheated combustion technology at a combustion temperature of 900 °C and a decarbonization activation time of 4 min. The mechanism of the effect of different Na2SO4 dosages on the performance of PCCPB was investigated using comprehensive tests (including mechanical property tests, microscopic tests, and leaching toxicity tests). The results show that the uniaxial compressive strength (UCS) of C-S2, C-S3, and C-S4 can meet the requirements of backfill mining, among which the UCS of C-S3 with a curing time of 3 d and 28 d were 0.545 MPa and 4.312 MPa, respectively. Na2SO4 excites PCCPB at different curing time, and the UCS of PCCPB increases and then decreases with the increase in Na2SO4 dosage, and 3% of Na2SO4 had the best excitation effect on the late strength (28 d) of PCCPB. All groups' (control and CS1-CS4 groups) leachate heavy metal ions met the requirements of groundwater class III standard, and PCCPB had a positive effect on the stabilization/coagulation of heavy metal ions (Mn, Zn, As, Cd, Hg, Pb, Cr, Ba, Se, Mo, and Co). Finally, the microstructure of PCCPB was analyzed using FTIR, TG/DTG, XRD, and SEM. The research is of great significance to promote the resource utilization of coal CG residual carbon and realize the sustainable consumption of coal CG activation on a large scale.

[Transformation of Nitrogen Nutrients in the Urban Sewage Pipe Network].

The paper focuses on the changes of nitrogen compounds in the Pipe network. A 1.2km long urban sewage simulation network with artificial water distribution was selected as the research subject. Then we analyzed and evaluated the change characteristics of nitrogen nutrients along the pipe. The results proved that ammonium chloride as the nitrogen source matrix, which was necessary for microorganisms in the Pipe to survive and proliferate. Free amino acids, combined amino acids and nucleic acid produced by metabolism were the major nitrogenous organic compounds. Among which, amino acids accounted for dissolved organic nitrogen (DON) in the majority. The characterization results of three-dimensional fluorescence spectroscopy and size exclusion chromatography showed that the characteristic fluorescence peak of organic matter in waste water was increased, and the protein ( tyrosine, tryptophan)--based fluorescence intensity gradually increased along the pipe. It was also found that small molecules of nutrients in the water were converted to complex organic molecules under the assimilation of microorganisms.