Mainstream anaerobic treatment has the potential to capture organic energy, and represents a sustainable development trend, but with the problems of low biogas quality and dissolved methane emissions. In this study, methane-driven ammonia recovery of anaerobic effluent was proposed. A 380-day long-term experiment, which was divided into four phases according to different aeration modes, was conducted. The ammonia conversion and microbial characteristics shows that ammonia oxidizing bacteria (AOB) were constrained during Phases 2 (DO: <0.2 mg L −1 ) and 4 (DO: 0.1–1.6 mg L −1 ), and were active during Phase 3 (DO: 2–4 mg L −1 ). During phase 4, when the intermittent aeration was used, the total nitrogen removal rate was higher than during Phases 2 and 3, and nearly 100% ammonia was removed. Methylomonas , a genus of methane oxidizing bacteria (MOB), was enriched during Phase 4. The serum bottle experiment confirmed that the ammonia removal occurred through the MOB assimilation. The protein content in the CH 4 -added group was 35.5%, which was higher than in the group without CH 4 (23.3%). The powerful ammonia assimilation and protein synthesis capabilities of MOB give a meaning to the anaerobic effluent for ammonia recovery and protein production. Intermittent aeration could be used to constrain AOB and improve ammonia recovery efficiency.
Phospholipids (PLs), the main lipid component in marine shellfish, consist mainly of glycerophosphocholine (GPC) and glycerophosphoethanolamine (GPE). This work compared the oxidative susceptibility of GPC and GPE in dried shellfish during storage and also investigated the effects of natural phenolic antioxidant on such oxidative susceptibility. The content of four representative polyunsaturated fatty acids (C18:3 n-3, C20:4 n-6, C20:5 n-3, and C22:6 n-3) esterified onto GPC or GPE in dried scallop adductor muscle during storage at two temperatures were matched with first-order kinetic models, in order to ascertain the oxidation reaction rate constant ( k ). The results showed that GPE possessed greater oxidation rate than GPC during storage, and GPC could be more effectively protected by the antioxidants of bamboo leaves (AOB, polar polyphenolic antioxidants) compared with GPE. This study provides a practical method for accurate evaluation of oxidative susceptibility of different PL classes in complex food systems.
Phthalic acid esters (PAEs) pollution has become an increasing issue worldwide, but little is known about its effects on ammonia-oxidizers and nitrous oxide (N 2 O) in the soil environment. Here, a 50-day soil microcosm experiment was conducted using low and high doses bis (2-Ethylhexyl) phthalate (DEHP) to estimate the effect of DEHP exposure on soil N 2 O emissions and the nitrifying community in calcareous soil. The results showed that DEHP exposure at 10 and 100 mg kg -1 doses significantly reduced N 2 O by 67.5% and 73.6%, respectively, relative to the DEHP absent treatment. The microbial biomass carbon and nitrogen (MBC and MBN) were consistently and significantly decreased with DEHP exposure at 5, 22, and 50 days after incubation, especially with high-dose. The bipartite association networks showed that DEHP exposure changed the compositions of both ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) communities. Moreover, the AOA and AOB amoA gene abundances were significantly decreased by DEHP addition to the soil ( P < 0.05). Random forest modeling showed that the AOB Shannon index and pH were the most important biotic and abiotic factors affecting N 2 O emissions in the soil with DEHP exposure, respectively. Partial least squares path modeling (PLS-PM) demonstrated that the reduction of N 2 O emissions due to DEHP exposure was mainly ascribed to the changes of the AOB community. The results from this study highlight the toxicity of DEHP on the ammonia oxidizers, and its mitigating effect on N 2 O emissions in the soil where ammonia-oxidation is largely driven by AOB.
危险品化学品经营许可证（带存储）