Organic carbon release, denitrification performance and microbial community of solid-phase denitrification reactors using the blends of agricultural wastes and artificial polymers for the treatment of mariculture wastewater
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This paper explored the possibility of heterotrophic denitrification driven by composite solid carbon sources in low carbon/nitrogen ratio marine recirculating aquaculture wastewater. In this study, two agricultural wastes, reed straw (RS), corn cob (CC) and two artificial polymers, polycaprolactone (PCL), poly3-hydroxybutyrate-hydroxypropionate (PHBV) were mixed in a 1:1 ratio to compare the carbon release characteristics of the four composite carbon sources (RS+PCL, RS+PHBV, CC+PCL, and CC+PHBV) and their effects on improving the mariculture wastewater for denitrification. Dissolved organic carbon (DOC) after carbon source release (4.96-1.07 mg/g), total organic carbon/chemical oxygen demand (1.9-0.79) and short-chain fatty acids (SCFAs) (4.23-0.21 mg/g) showed that all the four composite solid carbon sources had excellent organic carbon release ability, and the CC+PCL group had the highest release of DOC and SCFAs. Energy-dispersive X-ray spectroscopy, scanning electron microscopy, and Fourier-transform infrared spectroscopy were used to observe the changes in the surface characteristics of the composite carbon source before and after application. And results showed that the stable internal structure enabled CC+PCL group to have continuous carbon release performance and achieved the maximum denitrification efficiency (93.32 %). The NRE results were supported by the abundance of the Proteobacteria microbial community at the phylum level and Marinobacter at the genus level. Quantitative real-time PCR (q-PCR) indicated CC-containing composite carbon source groups have good nitrate reduction ability, while PCL-containing composite carbon source groups have better nitrite reduction level. In conclusion, the carbon source for agricultural wastes and artificial polymers can be used as an economic and effective solid carbon source for denitrification and treatment of marine recirculating aquaculture wastewater.Keywords:
Carbon fibers
With the purpose to solve the problems in the bio-denitrification process,a strain with denitrification ability was separated and identified as Pseudomonas stutzeri. Complex denitrification sludge was cultured by the coupling growth of the strain and bio-active carbon sludge,and the denitrification properties were studied. Results showed that the microphoto shape of the complex denitrification sludge was granular irregularly with no filamentous bacteria. SVI was 38~55mL/g and VSS was 2.0g/L. As for the different denitrification substrates such as NO3--N and NO2--N,the denitrification curves were similar. There was substrates competitive relationship between NO3--N and NO2--N when they coexisted in the same simulated wastewater,but no inhibitive effect occured by NO2--N. When DO was below 0.5mg/L,the denitrification effect was good,and in the high pH of 9.3,denitrification could take place well. The volume loading could get to 0.9kgNO3--N(/m·3d).
Pseudomonas stutzeri
Aerobic denitrification
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Automated carbon analyzers often are configured to provide estimates of both total organic carbon (TOC) and nonpurgeable organic carbon (NPOC). We show there can be an overestimation of total carbon in the presence of moderate to large quantities of dissolved inorganic carbon. This leads to overestimates of TOC, which is measured as the difference between total carbon and inorganic carbon. Water samples were analyzed as both TOC and NPOC on a Shimadzu TC 5050 Carbon Analyzer. The difference between TOC and NPOC increased as a function of concentrations of dissolved inorganic carbon (DIC). Water samples spiked with DIC ranging from 0 to 100 mg DIC/L also reported increased TOC as large as 8 mg C/L. Our data suggest that the Shimadzu 5050 analyzer (and by analogy other instruments that estimate TOC by difference between TC and IC) overestimates total carbon (TC) when calibrated with an organic standard as recommended by the manufacturer. The magnitude of the overestimation varies both with the amount of DIC present in the sample and the extent to which measurement efficiency of the analyzer is less than 100%. The consequences will be most severe in analysis of samples from systems spanning a large range in DIC. Time series from individual systems are less likely to be affected because the necessary large change in DIC would be detected as changes in pH or other attributes well before any change in DOC. Systems with high DIC will, however, be susceptible to even small variations in measurement efficiency.
Total inorganic carbon
Carbon fibers
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The denitrification of UNITANK was studied by using activated sludge mathematical model ASM2D,through which the basic factors affecting denitrification can be understand,the denitrification ability can be predicted and the denitrification in sedimentation area can be early alarmed as well.The results showed the triple-tank structure was not good for nitrogen removal of denitrification;tank B with anoxic condition can realize partially denitrification;Denitrification carried out mainly in sedimentation area,but as carbon source was deficient,denitrification efficiency was not high and further denitrification could lead to the risk of sludge floating.
Sedimentation
Carbon source
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Sediment collected from 11 sites within the Fox and East Rivers of Brown County, Wisconsin, and two near-shore sites in Green Bay (Lake Michigan) were analyzed for organic carbon content and various pesticides, polychlorinated biphenyls (PCBs), chlorodibenzodioxins, chlorodibenzofurans, polycyclic aromatic hydrocarbons (PAHs), sulfur and heavy metals. Representative chemicals from the organic and inorganic groups were examined for their concentrations at the various sites relative to organic carbon content. Correlations between organic carbon and contaminant concentrations resulted in simple linear regression models with high degrees of predictive capability for most chemicals. For example, chemical concentration relationships with organic carbon (r{sup 2}) were p,p{prime}-DDE (0.85), total PCBs (0.69), 2,3,7,8-tetrachlorodibenzodioxin (0.76), 1,2,3,6,7,8-hexachlorodibenzodioxin (0.87), 2,3,7,8-tetrachlorodibenzofuran (0.71), fluoranthene (0.46), pyrene (0.51), total sulfur (0.75), cadmium (0.76), copper (0.84), lead (0.85), zinc (0.80), chromium (0.04), and nickel (0.39). All correlations were positive with the exception of nickel. This suggests that contaminants within the lower Fox River/Green Bay system are at steady-state with respect to organic carbon. Knowledge of relationships such as this within aquatic systems may be useful in planning and budgeting contaminant mass balance studies within the systems.
Fluoranthene
Carbon fibers
Biomagnification
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Denitrification is increasingly recognized for its ability to eliminate or reduce nitrate concentrations in groundwater. With this awareness comes a desire to predict the rate and extent of denitrification in aquifers. The limiting factor in making predictive models, however, is our limited knowledge of the physical characteristics of this process. This review synthesizes the published literature on natural aquifer denitrification. A background section discusses denitrification requirements and dissimilatory nitrate reduction to ammonium, which occurs in environments similar to those where denitrification occurs, and gives a historical perspective on denitrification. Other sections discuss denitrification with organic carbon serving as the electron donor (heterotrophic denitrification) and with reduced inorganic compounds serving as the electron donor (autotrophic denitrification). The section on heterotrophic denitrification is structured around two tables that summarize natural aquifer denitrification rates reported by laboratory studies and natural aquifer denitrification rates reported by field studies. The section on autotrophic denitrification discusses denitrification with reduced iron and reduced sulfur. Thus far, most studies only consider a single electron donor or donor type, whether heterotrophic or autotrophic. This review demonstrates, however, that multiple electron donors may be present in a given aquifer. Future research efforts are recommended to determine the factors affecting the availability of electron donors and their denitrification rates. Additional research is also suggested on how dissolved oxygen affects denitrification rates and on the factors influencing the partitioning of nitrate reduction products to nitrous oxide, a potential contributor to the destruction of the ozone layer, and to ammonium.
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这研究的目的是由外部碳来源的增加调查 denitrification potentialenhancement 并且用率(NUR ) 批测试的硝酸盐利用估计 denitrification 潜力 forthe predenitrification 系统。它被看 thatthe denitrification 潜力能实质地与三 externalcarbon 来源的增加被增加，即分别地，甲醇，乙醇，和醋酸盐，和乙醇，醋酸盐，和甲醇的 denitrification 率到达了直到 9.6,12 ，和 3.2 mgN/( g VSS-h )当那 ofstarch 废水仅仅是 0.74 mgN/( g VSS-h )时。由比较，乙醇被发现是 bestexternal 碳来源。有淀粉废水和浪费乙醇的 NUR 批测试是潜力由于 NUR 测试，废水特征和运动参数的浪费乙醇 addition.By 工具从 5.6～16.5 mg NO3-N/L 增加了的带的 out.The denitrification 能被估计，它被用来决定废水的 denitrification 潜力，计算植物的 thedenitrification 潜力并且预言硝酸盐自河质量，也为开发碳剂量控制 st 的 asprovide 信息
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Abstract Under marine conditions, tributyltin (TBT) is speciated mainly as an uncharged hydroxyl complex (TBTOH) that is expected to have a similar fate to hydrophobic organic contaminants. Earlier studies indicated that for the later compounds, sorption to black carbon (BC) can be more than two orders of magnitude stronger than sorption to organic carbon, notably at low and environmentally relevant concentrations. The aim of the present study was to investigate the sorption strength of spiked TBT to a sediment and its BC isolate. It was observed that carbon‐normalized sorption coefficients were in the same range for the sediment total organic carbon (TOC) and for its BC (log K TOC 5.05 L/kg TOC and log K BC 5.09 L/kg BC , respectively). This indicates that TBT does not sorb as strongly to BC as other hydrophobic organic contaminants. Activated carbon (AC), a strong man‐made sorbent, has the potential to be used for in situ remediation of contaminated sediments and soils, in particular for polycyclic aromatic hydrocarbons and polychlorinated biphenyls. In the present study, both granular and powdered AC were found to strongly sorb TBT under marine conditions, with a log sorption coefficient of 6.8 L/kg carbon . Tributyl‐ and dibutyltin concentrations in the pore water of a natively contaminated sediment were reduced by more than 70% on addition of 2% of powdered AC, whereas granular AC did not show a similar reduction. The results indicate that powdered AC might be a feasible remediation agent for sediments contaminated by organotins.
Carbon fibers
Pentachlorophenol
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Denitrification plays important roles in nitrogen cycling and management affecting both the environment and agricultural systems. Potential denitrification has a role in comparison of denitrification magnitudes in different soils. This paper discusses the concept of potential denitrification in relation to denitrification rate and conditions under which it is determined. The terminologies such as denitrification activity, intensity, capacity and potential are variously applied to describe denitrification rates, but the use of these terms is not consistent. Similarly, the concept of potential denitrification is variously espoused. Many researchers measure potential denitrification under entirely different conditions and express the values in divergent units making meaningful comparisons between soils unfeasible. It is proposed that the concept of potential denitrification embraces the principle of maximum attainable denitrification rate under optimal conditions within the limitations of natural setting. The steepest slope, Y/X, on the cumulative nitrous oxide production - time curve defines the potential denitrification value. The conditions under which potential denitrification is to be measured and the units in which its values are to be expressed are discussed.
Keywords: denitrification activity, denitrification capacity, denitrification intensity, denitrification rate, potential denitrification Resume
La denitrification joue un role important dans le cycle et la gestion de l'azote et affecte l'environnement et les systemes agricoles. La denitrification potentielle intervient egalement lors de la comparaison des degres de denitrification dans differents sols. Cet article revoit le concept de la denitrification potentielle par rapport au taux de denitrification et les conditions sous lesquels on la determine. Les terminologies telles qu'activite, intensite, capacite et potentiel de denitrification sont differemment appliquees pour decrire les taux de denitrification, mais l'utilisation de ces termes manque de consistance d'ou le concept de la denitrification potentielle est compris differemment. Beaucoup de chercheurs mesurent la denitrification potentielle dans des conditions entierement differentes et en expriment les valeurs en unites diverses, ce qui rend impossible des comparaisons utiles entre les sols. On propose que le concept de denitrification potentielle couvre le principe du taux possible de denitrification maximale dans des conditions optimales et dans les limites des conditions naturelles. La pente la plus raide, , Y/X, sur la production cumulative du protoxyde d'azote, sur la courbe obtenue au cours d'une periode, definit la valeur potentielle de denitrification. Les conditions sous lesquelles la denitrification potentielle doit etre mesuree, et les unites dans lesquelles ses valeurs doivent etre exprimees sont passees en revue.
Mots cles: activite de denitrification, capacite de denitrification, intensite de denitrification, taux de denitrification, denitrification potentielle
(Discovery and innovation: 14(1-2): 84-91)
Nitrous oxide
Nitrogen Cycle
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The effect of temperature on denitrification and short-cut denitrification with additional carbon source of acetate in a Sequencing Batch Reactor(SBR) was investigated.Two types of denitrification proceeded drastically and the average specific denitrification rate(rDN) of short-cut denitrification was 1.312 times greater than that of denitrification under the same temperature.With the decrease of temperature,both specific denitrification rates slowed down,whereas the change of 20~10 ℃ had greater influence on two types of denitrification than that of 30~20℃ and the denitrification of nitrite was influenced by low temperature even more greatly.Besides,the reduction of nitrate to nitrite was inhibited under the range of 10~15 ℃.When the initial concentration of electron acceptors and pH value were same,pH value produced in the two systems increased with the decreasing of temperature and the apex on pH profile of short-cut denitrification was higher at the same temperature.
Aerobic denitrification
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