Display omitted
•Chlorella powder can enhance phenols removal and short-cut denitrification;•Removal ratios of COD, TPh, NO2−-N, and TN were 96.91, 98.60, 99.50, and 96.36% with 180 mg/L ...Chlorella;•The addition of Chlorella powder improved stability and sedimentation of sludge;•Comamonas, Povalibacter, Acidaminobacter, and Youngiibacter were functional bacteria.
Large amount of phenols and nitrogen in coal pyrolysis wastewater have become a major bottleneck that restricts industrial development. There are few studies on enhanced phenol treatment and short-cut denitrification with dried Chlorella powder as carbon source in coal pyrolysis wastewater treatment. This study aimed to explore the effects of sodium acetate, glucose, and Chlorella powder as carbon source on enhanced treatment of phenolic compounds and NO2−-N in coal pyrolysis wastewater. The appropriate dosage of Chlorella powder was 180 mg/L in the reactor. The corresponding removal ratios of chemical oxygen demand (COD), total phenol (TPh), NO2−-N, and total nitrogen were 96.91%, 98.60%, 99.50%, and 98.60%, respectively. The pH of influent in reactor with Chlorella powder should be maintained between 6.5 and 7.5, whereas the hydraulic retention time (HRT) should be maintained above 8 h. Sodium acetate, glucose, and Chlorella improved the stability and sedimentation of sludge. Addition of Chlorella powder in the reactor resulted in the enrichment of Comamonas (5.83%), Povalibacter (9.53%), Acidaminobacter (13.41%), Youngiibacter (8.81%), Flavobacterium (5.09%), and Gemmobacter (5.03%). Among these, Comamonas, Povalibacter, Youngiibacter, Flavobacterium, and Gemmobacter are phenolic compounds degrading functional bacteria, whereas Povalibacter, Flavobacterium, and Gemmobacter are short-cut denitrification functional bacteria. Combined with economic analysis, the results revealed that Chlorella powder has advantages of good treatment effect, easy addition, low direct cost, and low operation and maintenance cost. Thus, Chlorella powder can be used as an alternative carbon source for phenol degradation and short-cut denitrification of coal pyrolysis wastewater.
•Selectivity shift towards ammonia production on ERN by tuning the electrode/electrolyte interface.•Alkali metal cations in the electrolyte impact nitrate and nitrite removal on tin electrode.•Cs+ ...cations at the electrode/electrolyte interface enhance nitrate removal and ammonia production.
This article explores how electrolyte engineering can control product selectivity and kinetics of electrochemical reduction of nitrate (ERN). This is an alternative approach to the conventional catalyst engineering methodology for controlling the electrode/electrolyte interface and impacting on ERN activity and selectivity. Electrolytic treatment was conducted in a membrane-less plug flow reactor (PFR) under batch recirculation using a tin cathode. Operational parameters related to solution flow rate, mass transport regime, initial pH, and dissolved oxygen demonstrated to have negligible impact on nitrate (NO3–) removal under the operation conditions studied. In stark contrast, the presence of different alkali cations in solution (Li+, Na+, K+ and Cs+) sharply impacted on NO3– removal rate and steered product selectivity in ERN, as well as they did it for the case of nitrite (NO2–) reduction reaction. An evident increase in ammonia (NH3) production is achieved in both NO3– and NO2– removal by following the order Li+ < Na+ ≈ K+ < Cs+. These close tendencies observed for NO3– and NO2– reduction reactions point to the electrostatic effect stabilizing negatively charged species at the electrode interface as the main responsible of selectivity modulation through electrolyte engineering. Thus, we present the first evidence of a significant shift in products selectivity in ERN from Ngas towards NH3 production on tin electrodes by tuning the electrode–electrolyte interface with suitable cations. Furthermore, an approximately 2-fold decrease in electrical energy per order is achieved by solutions containing Cs+ instead of Li+ for both NO3– and NO2– reduction reactions. These results open the pathway towards understanding interfacial impacts associated to different ionic species present in solution that can enhance electrochemical pollutants removal, and resource recovery, as well as lowering the process cost.
The effects of 12 bacterial amendments on reducing concentrations of total ammonia nitrogen (TAN), nitrite nitrogen (NO2−N) and organic matter in pond waters were evaluated in the laboratory. ...Concentrations of TAN, NO2−N and organic matter in untreated water (controls) naturally decreased with time during 16days. No large acceleration in nitrification or organic matter oxidation was observed from using these bacterial amendments. However, minor differences in concentrations of TAN and NO2−N, and rates of dissolved oxygen loss – an indicator of decomposition rate – were found between controls and treatments on some sampling dates. Compared to the controls, the bacterial amendment 5 at the manufacturer's recommended dose resulted in lower TAN concentrations on days 8 and 12, less NO2−N on days 6 and 8 and less oxygen loss on day 1. Water treated with the bacterial amendments 3 and 10 at the recommended doses had slightly lower TAN concentrations on day 0 (soon after initial treatment) and day 16, respectively. The bacterial amendment 11 at the recommended dose lead to lower NO2−N concentration on day 12. Organic matter in water treated with the bacterial amendments 8 and 10 exhibited a greater rate of microbial respiration on day 16. With higher doses or more frequent applications, there was lower (P<0.05) TAN concentrations in water treated with the bacterial amendment 11 on day 0 and day 2. The bacterial amendment 10 at higher dose and the bacterial amendment 7 at more frequent applications than recommended by manufacturers had a small effect on oxygen rate loss on day 1 and days 7, 9 and 13, respectively. The bacterial amendments 1, 2, 4, 6, 9 and 12 were not successful (P>0.05) at lowering concentrations of TAN, and NO2−N or oxygen loss rate on any sampling dates.
Bacterial amendments are widely used in aquaculture in efforts to enhance water quality in ponds. This research showed no benefit of bacterial amendments on water quality in laboratory tests and doubts on the effectiveness of bacterial augmentation.
•Twelve bacterial water quality enhancers were tested under laboratory conditions.•The products did not accelerate oxidization of ammonia, nitrite, or organic matter.•It seems doubtful that bacterial augmentation is a beneficial practice in pond aquaculture.
Small-scale pond aquaculture is one of the fast-growing land use options in fragmented mountainous regions of southwest China. This study measured the quality of three purple soils from Kaizhou (S1), ...Bishan (S2), and Tongnan (S3) in the Sichuan Basin and assessed their potentials as aquaculture substrates through overlying water trials. The effects of the substrates on the immunity, metabolism, and thermal resistance of Hyriopsis cumingii were also investigated. Soil properties analysis showed that the three soils varied in pH, total organic matter, macro-nutrient, and micro-nutrient contents. The maximum total potassium and available potassium favorable for phytoplankton growth were observed in S3. The physicochemical parameters of the substrates in the overlying water trials concurred with the soil properties. Furthermore, soil enzymes may be used as indices of soil fishability. However, S1 and S2 soils were prone to leach noxious ammonia nitrogen (NH4+-N) and nitrite nitrogen (NO2−-N) in water columns. On the other hand, S3 soil maintained the dynamic balance of the antioxidant system in H. cumingii, activated the relative expression of their immune-related and metabolism-related genes, and improved their resistance to thermal stress. Principal component analysis suggested that NH4+-N and NO2−-N in the soil were key environmental factors that destroyed the antioxidant system and impeded the metabolic process of H. cumingii. Based on the findings, the soils were ranked in terms of their suitability for aquaculture as follows: S3 > S1 > S2. Our study will provide a scientific foundation for building inland aquaculture ponds and developing land use policies in China and around the world.
Display omitted
•The properties of purple soils from various strata in southwest China were tested.•Aquaculture substrate altered immunity, metabolism, and heat resistance of mussels.•NH4+-N and NO2−-N in water disrupted the balance of antioxidants and metabolism.•The purple soil from the Shaximiao Formation showed the best aquaculture suitability.
Nitrite (NO₂ ⁻-N) accumulation in denitrification can provide the substrate for anammox, an efficient and cost-saving process for nitrogen removal from wastewater. This batch-mode study aimed at ...achieving high NO₂ ⁻-N accumulation over long-term operation with the acetate as sole organic carbon source and elucidating the mechanisms of NO₂ ⁻-N accumulation. The results showed that the specific nitrate (NO₃ ⁻-N) reduction rate (59.61 mg N VSS⁻¹ h⁻¹ at NO₃ ⁻-N of 20 mg/L) was much higher than specific NO₂ ⁻-N reduction rate (7.30 mg N VSS⁻¹ h⁻¹ at NO₃ ⁻-N of 20 mg/L), and the NO₂ ⁻-N accumulation proceeded well at the NO₃ ⁻-N to NO₂ ⁻-N transformation ratio (NTR) as high as 90 %. NO₂ ⁻-N accumulation was barely affected by the ratio of chemical oxygen demand (COD) to NO₃ ⁻-N concentration (C/N). With the addition of NO₃ ⁻-N, NO₂ ⁻-N accumulation occurred and the specific NO₂ ⁻-N reduction rate declined to a much lower level compared with the value in the absence of NO₃ ⁻-N. This indicated that the denitrifying bacteria in the system preferred to use NO₃ ⁻-N as electron acceptor rather than use NO₂ ⁻-N. In addition, the Illumina high-throughput sequencing analysis revealed that the genus of Thauera bacteria was dominant in the denitrifying community with high NO₂ ⁻-N accumulation and account for 67.25 % of total microorganism. This bacterium might be functional for high NO₂ ⁻-N accumulation in the presence of NO₃ ⁻-N.
Environmental stress can disrupt the intricate interactions between the host and intestine microbiota, thereby impacting the host health. In this study, we aimed to elucidate the dynamic changes in ...the bacterial community within shrimp intestines under nitrite nitrogen (nitrite-N) stress and investigate potential host-related factors influencing these changes. Our results revealed a significant reduction in community diversity within the intestine exposed to nitrite-N compared to control conditions. Furthermore, distinct differences in community structures were observed between these two groups at 72 h and 120 h post-stress induction. Nitrite-N stress also altered the abundances of some bacterial species in the intestine dramatically. It is noteworthy that, in comparison to the 72 h, intestine bacterial community structure of stressed shrimp exhibited a significantly higher degree of dispersion after 120 h of nitrite-N stress when compared to control shrimp, and the relative abundance of numerous bacterial species experienced a substantial decrease or even reached 0 %. Moreover, it led to a reduction in bacterial community interactions and decreased competitiveness within the intestine microbiota. Notably, the influence of bacterial community assemblies in the shrimp intestine shifted from a stochastic process to a deterministic one after 24 h and 72 h of nitrite-N stress, returning to a stochastic process at 120 h. We further observed a close association between this phenomenon and host's response to nitrite-N stress. Expression levels of differentially expressed genes in the intestinal tissue significantly impact the intestine bacterial diversity and abundance of species. In particular, the significant decline in bacterial diversity and abundances of quite a few species in intestine was attributed to the up-regulation of peritrophin-48-like. Overall, nitrite-N stress indeed disrupted the intestine microbiota and changed the host-microbiota interactions of shrimp. This study offered novel insights into environment-host-microbiota interactions and also provided practical guidance for promoting healthy shrimp cultivation practices.
Display omitted
•Nitrite nitrogen stress disrupted the intestine bacterial community of shrimp.•Nitrite nitrogen stress changed the host-community interactions of shrimp.•Community disorder was associated with up-regulation of peritrophin-48-like.
Concerns over the impacts of water pollution and a need for sustainable development have led to the exploration of various approaches to mitigating the nutrient enrichment in surface waters. An ...integrated floating island system consisted of aquatic vegetation near riversides and mosaic floating island with adsorptive biofilms was constructed to purify eutrophic river water in Jiaxing City, Zhejiang Province. This study indicated that average removal rates for total nitrogen (TN), NH4+-N, NO3−-N NO2−-N, total phosphorus (TP) and chlorophyll a in summer–autumn season were 36.9%, 44.8%, 25.6%, 53.2%, 43.3% and 64.5%, respectively, which were 16.2%, 18.4%, 12.8%, 25.8%, 26.3% and 58.7% higher than those respective values in winter–spring season. In addition, it also effectively reduced the concentrations of total suspended substance (TSS), Escherichia coli and heavy metals. Due to greater biomass, alligator flag (Thalia dealbata) showed the greatest element uptake, with 60.9gNm−2, 8.2gPm−2, 856.6gCm−2 and 6.2gSm−2 respectively. The tested hydrophytes contained abundant crude protein ranging from 128gkg−1 to 255gkg−1 and Ca, Mg, Fe and Mn. Feasibility of the plant biomass used as animal feed to meet nutritional and safety requirements is discussed.
The patterns of spatial and temporal shifts in bloom‐forming cyanobacteria and the driving factors for these patterns were determined by analyzing the distribution of these cyanobacteria in Lake ...Chaohu using data from satellite images and field samples collected during 2012 and 2013. The cyanobacterial blooms primarily occupied the western region of Lake Chaohu, and the direction and speed of the prevailing wind determined the spatial distribution of these blooms. The cyanobacteria in Lake Chaohu were dominated by species of Microcystis and Anabaena. Microcystis reached its peak in June, and Anabaena had peaks in May and November, with an overall biomass that was higher than that of Microcystis. Microcystis generally occupied the western region of the lake in summer, whereas Anabaena dominated in other regions and seasons. Temperature may be responsible for these seasonal shifts. However, total phosphorus (TP), pH, temperature, turbidity and nitrate/nitrite nitrogen determined the coexistence of the two genera in different regions in summer. TP was correlated with Microcystis dominance, and pH and light availability were correlated with Anabaena dominance. Our results contribute to the understanding of shifts in bloom‐forming cyanobacteria and are important for the control of cyanobacterial blooms.
In the present experiment, eighteen aerobic denitrifying
Bacillus strains were isolated by BTB plate technique. The
Bacillus sp. strain YX-6 was selected for the aerobic denitrification studies ...because it is highly effective in removing nitrite compared with other strains of
Bacillus sp. The results indicated that the strain YX-6 could degrade the nitrite nitrogen (nitrite-N) from 10
mg/L to zero in 14
h and the nitrite-N degradation rate was approximately to 100% at the DO concentration of 5.2–5.8
mg/L. Furthermore, the aerobic denitrification of the strain YX-6 was significantly higher than those of the positive controls under different pH, temperature, nitrite and salinity concentrations (
p
<
0.05
). The amplification of nitrite reductase confirmed that the strain YX-6 contained the
nirS gene. According to the morphological observation and 16SrRNA gene analysis, the strain YX-6 was identified as
Bacillus coagulans.
