The Experts below are selected from a list of 25407 Experts worldwide ranked by ideXlab platform

Hongqiang Ren - One of the best experts on this subject based on the ideXlab platform.

David L. Sedlak - One of the best experts on this subject based on the ideXlab platform.

Zhi-wu Wang - One of the best experts on this subject based on the ideXlab platform.

  • Understanding the formation of recalcitrant Dissolved Organic Nitrogen as a result of thermal hydrolysis and anaerobic digestion of municipal sludge
    Environmental Science: Water Research & Technology, 2021
    Co-Authors: Dian Zhang, Mary Strawn, Tom Broderick, Wendell Khunjar, Zhi-wu Wang
    Abstract:

    This study for the first time investigated the turnover of Dissolved Organic Nitrogen in lab-scale thermal hydrolysis pretreatment at different temperatures with and without mesophilic anaerobic digestion at a solids retention time of 15 days.

  • Understanding the formation of recalcitrant Dissolved Organic Nitrogen as a result of thermal hydrolysis and anaerobic digestion of municipal sludge
    Environmental Science: Water Research & Technology, 2021
    Co-Authors: Dian Zhang, Mary Strawn, Tom Broderick, Wendell Khunjar, Zhi-wu Wang
    Abstract:

    This study for the first time investigated the turnover of Dissolved Organic Nitrogen (DON) in lab-scale thermal hydrolysis pretreatment (THP) operated for 2.5 hours at different temperatures with and without mesophilic anaerobic digestion (AD) at a solids retention time of 15 days. Results showed that THP at the temperature ranging from 110 to 190 °C substantially increased the levels of recalcitrant Dissolved Organic Nitrogen (rDON) by 110–310% as defined by DON that can survive aerobic incubation for more than 3 days at oxygen utilization rates

  • Recalcitrant Dissolved Organic Nitrogen formation in thermal hydrolysis pretreatment of municipal sludge.
    Environment international, 2020
    Co-Authors: Dian Zhang, Wendell Khunjar, Yiming Feng, Haibo Huang, Zhi-wu Wang
    Abstract:

    Thermal hydrolysis pretreatment (THP) has been considered as an advanced approach to enhance the performance of anaerobic digestion treating municipal sludge. However, several drawbacks were also identified with THP including the formation of brown and ultraviolet-quenching compounds that contain recalcitrant Dissolved Organic Nitrogen (rDON). Melanoidins produced from the Maillard reaction between reducing sugar and amino group have been regarded as a representative of such compounds. This review presented the state-of-the-art understanding of the mechanism of melanoidin formation derived from the research of sludge THP, food processing, and model Maillard reaction systems. Special attentions were paid to factors affecting melanoidin formation and their implications to the control of rDON in the sludge THP process. These factors include reactant availability, heating temperature and time, pH, and the presence of metallic ions. It was concluded that efforts need to be focused on elucidating the extent of the Maillard reaction in sludge THP. This paper aims to provide a mechanistic recommendation on the research and control of the THP-resulted rDON in municipal wastewater treatment plants.

Paul Westerhoff - One of the best experts on this subject based on the ideXlab platform.

  • Improved analysis of Dissolved Organic Nitrogen in water via electrodialysis pretreatment
    Analytical chemistry, 2015
    Co-Authors: Anbang Zhu, Baiyang Chen, Liang Zhang, Paul Westerhoff
    Abstract:

    This study evaluated electrodialysis (ED) for direct, accurate, and precise Dissolved Organic Nitrogen (DON) analysis in water. Unlike conventional methods that calculate DON as the difference between total Dissolved Nitrogen (TDN) and Dissolved inOrganic Nitrogen (DIN), we designed a compact ED reactor as a pretreatment tool that completely separates DIN from DON in water and then measures DON by equating DON to TDN. The experiments confirmed that the ED pretreatment process can achieve 99% removal of all three major DIN species (i.e., ammonia, nitrite, and nitrate) and an average recovery rate of 88% for an array of model DON compounds of varying characteristics (e.g., urea, amino acids, tripeptide, protein, and humic substances). Variations in Nitrogen removal and recovery might be explained by a combined effect of molecular weight, acid dissociation ability (pKa), aromaticity, and ED reactor configurations. For model solutions with DIN/DON ratios varying from 1 to 10 mg-N/mg-N, the relative standard d...

  • Application of Pretreatment Methods for Reliable Dissolved Organic Nitrogen Analysis in Water-A Review
    Critical Reviews in Environmental Science and Technology, 2014
    Co-Authors: Baiyang Chen, Anbang Zhu, Paul Westerhoff, Liang Zhang, Xin Yang, Chao Wang
    Abstract:

    Dissolved Organic Nitrogen (DON) is ubiquitously present in the environment, and its occurrence plays important roles in Nitrogen cycling and water safety issues. However, analytical techniques for DON are currently not well established. The DON data obtained from conventional methods by subtracting Dissolved inOrganic Nitrogen (DIN, including nitrate, nitrite, and ammonia) from total Dissolved Nitrogen (TDN) are subject to aggregated analytical errors and therefore can be low in precision and accuracy. To minimize the subtraction-induced errors, in recent years scientists have examined several pretreatment methods to achieve either direct detection or more reliable analysis of DON. The key challenge is to maximize the extents of DIN removal and DON recovery simultaneously. This review summarizes these pretreatment methods within four categories: (1) membrane methods, (2) adsorptive methods, (3) catalysis methods, and (4) preconcentration methods. By identifying the advantages and disadvantages of each me...

  • Dissolved Organic Nitrogen as a precursor for chloroform, dichloroacetonitrile, N-nitrosodimethylamine, and trichloronitromethane.
    Environmental science & technology, 2007
    Co-Authors: Wontae Lee, Paul Westerhoff, Jean-philippe Croué
    Abstract:

    Nitrogen-containing disinfection byproducts (N-DBPs) are potentially toxic. This study assessed the formation of three N-DBPs (dichloroacetonitrile (DCAN), trichloronitromethane (TCNM), and N-nitrosodimethylamine (NDMA)) and one regulated DBP (chloroform) upon adding free chlorine and monochloramine into solutions containing different fractions (hydrophobic, transphilic, hydrophilic, and colloidal) of Dissolved Organic matter (DOM) isolates (n = 17). We hypothesized that N-DBP formation would increase for Organic matter enriched in Organic Nitrogen. Formation potential tests were conducted with free chlorine or preformed monochloramine. Chloramination formed, on average, 10 times lower chloroform concentrations, but 5 times higher DCAN concentrations, as compared with free chlorine addition. The formation of the two halogenated N-DBPs (DCAN and TCNM) increased as the Dissolved Organic carbon (DOC) to Dissolved Organic Nitrogen (DON) ratio decreased upon adding free chlorine, but the N-DBP formation was re...

  • Dissolved Organic Nitrogen removal during water treatment by aluminum sulfate and cationic polymer coagulation
    Water Research, 2006
    Co-Authors: Wontae Lee, Paul Westerhoff
    Abstract:

    Abstract Coagulation of three surface waters was conducted with aluminum salt and/or cationic polymer to assess Dissolved Organic Nitrogen (DON) removal. Coagulation with aluminum sulfate removed equal or slightly lower amounts of DON as compared to Dissolved Organic carbon (DOC). At aluminum sulfate dosages up to 5 mg per mg DOC, the cationic polymer improved DON removal by an additional 15% to 20% over aluminum sulfate alone. At very high aluminum sulfate dosages (>8 mg aluminum sulfate per mg DOC), however, the cationic polymer addition negligibly increased DON removal. Molecular weight fractionation before and after coagulation experiments indicated that cationic polymer addition can increase the removal of all molecular weight fractions of DON with the highest molecular weight fraction (>10,000 Da) being preferentially removed. Results indicated that the DON added as part of the cationic polymer was almost completely removed at optimum aluminum sulfate and polymer doses.

  • Occurrence and removal of Dissolved Organic Nitrogen in US water treatment plants
    Journal - American Water Works Association, 2006
    Co-Authors: Wontae Lee, Paul Westerhoff, Mario Esparza-soto
    Abstract:

    Two seasonal sampling campaigns of raw and finished waters from 28 water treatment plants were conducted to investigate the occurrence and removal of Dissolved Organic Nitrogen (DON). A new dialysis pretreatment technique was applied for accurate DON determination. The average DON concentration was 0.186 mg/L Nitrogen (N) in raw waters and 0.148 mg/L N in finished waters. On average, total Dissolved Nitrogen in the raw waters consist of 10% DON and 90% Dissolved inOrganic Nitrogen. The Dissolved Organic carbon (DOC)-to-DON ratio of raw waters averaged 18 mg DOC to 1 mg DON. DON removal during water treatment closely mirrored that of DOC removal. The molecular weight distribution of DON roughly parallels that of DOC, and higher-molecular-weight fractions (> 10,000 D) of both DON and DOC were preferentially removed across the full-scale water treatment plants.

Deborah A. Bronk - One of the best experts on this subject based on the ideXlab platform.

  • Abiotic effects on effluent Dissolved Organic Nitrogen along an estuarine transect.
    Water environment research : a research publication of the Water Environment Federation, 2015
    Co-Authors: Carolina P. Funkey, Robert J. Latour, Deborah A. Bronk
    Abstract:

    Biological nutrient removal is a process commonly used in water resource recovery facilities to reduce Dissolved inOrganic Nitrogen (DIN) concentrations in effluent; this process is less effective at removing all of the effluent Dissolved Organic Nitrogen (EDON). The goal of this study was to investigate the fate of EDON after it undergoes the disinfection process and enters receiving waters. The authors quantified the abiotic effects of effluent exposure to sunlight, increased salinity, and a combination of the two factors. Effluent Dissolved Organic Nitrogen showed significant breakdown during the disinfection process (UV and chlorine) and when exposed to sunlight and increasing salinity. Approximately 7% of the EDON was transformed to DIN and Dissolved primary amines after exposure to 9 hours of sunlight and a salinity increase from 0 to 33. The production of DIN and primary amines should be taken into account when considering sources of labile Nitrogen to aquatic ecosystems.

  • Chapter 4 – Dynamics of Dissolved Organic Nitrogen
    Biogeochemistry of Marine Dissolved Organic Matter, 2015
    Co-Authors: Rachel E. Sipler, Deborah A. Bronk
    Abstract:

    Dissolved Organic Nitrogen (DON) is that subset of the Dissolved Organic carbon (DOC) pool that also contains N. This chapter reviews four major areas of DON research. First, DON concentrations and distributions in aquatic environments are reviewed with respect to the methods used to analyze DON concentrations, global distributions, comparison of DON concentration across a range of aquatic systems and seasonal variations. Second, the composition of the characterizable and uncharacterized DON is reviewed with respect to pools of specific DON forms and the methods used to study and chemical characteristics of the fraction of the DON pool that is not defined. Third, sources of DON to the water column are reviewed with respect to autochthonous sources, allochthonous sources, methods used to measure rates of DON release and release rates of bulk DON and individual DON forms in the literature. The final section reviews sinks for DON with respect to DON bioavailability, methods used to estimate DON uptake rates, mechanisms that contribute to DON bioavailability, and DON uptake rates published in the literature. Recommendations for future research are presented for each research area. This chapter focuses on work published largely after 2001 and topics not included in the earlier review (Bronk, D.A., 2002. Dynamics of DON. In: Hansell, D.A., Carlson, C.A. (eds.) Biogeochemistry of Marine Dissolved Organic Matter. Academic Press, San Diego).

  • chapter 4 dynamics of Dissolved Organic Nitrogen
    Biogeochemistry of Marine Dissolved Organic Matter (Second Edition), 2015
    Co-Authors: Rachel E. Sipler, Deborah A. Bronk
    Abstract:

    Dissolved Organic Nitrogen (DON) is that subset of the Dissolved Organic carbon (DOC) pool that also contains N. This chapter reviews four major areas of DON research. First, DON concentrations and distributions in aquatic environments are reviewed with respect to the methods used to analyze DON concentrations, global distributions, comparison of DON concentration across a range of aquatic systems and seasonal variations. Second, the composition of the characterizable and uncharacterized DON is reviewed with respect to pools of specific DON forms and the methods used to study and chemical characteristics of the fraction of the DON pool that is not defined. Third, sources of DON to the water column are reviewed with respect to autochthonous sources, allochthonous sources, methods used to measure rates of DON release and release rates of bulk DON and individual DON forms in the literature. The final section reviews sinks for DON with respect to DON bioavailability, methods used to estimate DON uptake rates, mechanisms that contribute to DON bioavailability, and DON uptake rates published in the literature. Recommendations for future research are presented for each research area. This chapter focuses on work published largely after 2001 and topics not included in the earlier review (Bronk, D.A., 2002. Dynamics of DON. In: Hansell, D.A., Carlson, C.A. (eds.) Biogeochemistry of Marine Dissolved Organic Matter. Academic Press, San Diego).

  • Dissolved Organic Nitrogen: a dynamic participant in aquatic ecosystems
    Aquatic Microbial Ecology, 2003
    Co-Authors: Tom Berman, Deborah A. Bronk
    Abstract:

    In both marine and freshwaters, the concentration of Dissolved Organic Nitrogen (DON) frequently exceeds that of Dissolved inOrganic Nitrogen (DIN), including ammonium, nitrate, and nitrite. Recent evidence indicates that many Organic N compounds are released into the DON pool and taken up from this pool by planktonic microbiota on timescales of hours to days. This observation suggests that many components of the DON pool can play an active role in supplying N nutrition directly or indirectly to phytoplankton and bacteria and, in so doing, may affect the species composi- tion of the ambient microbial assemblage. Here we present an overview of the state of knowledge of DON pools in aquatic environments, focused mainly on data gathered in the last decade. We review information on DON concentrations in freshwater and marine systems, analytical methods for the determination of DON, and the biotic and abiotic sources and sinks of DON. More detailed discussion addresses specific components of the DON pool: urea, Dissolved combined and free amino acids, pro- teins, nucleic acids, amino sugars, and humic substances. The DON pool in natural waters is not inert and can be an important sink and source for N. There is a need for greater appreciation and under- standing of the potential role of DON as a dynamic participant in the Nitrogen cycle within aquatic ecosystems, particularly in freshwater environments.

  • release of Dissolved Organic Nitrogen by marine diazotrophic cyanobacteria trichodesmium spp
    Applied and Environmental Microbiology, 1994
    Co-Authors: Patricia M. Glibert, Deborah A. Bronk
    Abstract:

    Abstract Trichodesmium sp. is a filamentous, colonial cyanobacterium which contributes substantially to the input of Nitrogen in tropical and subtropical oceanic waters through Nitrogen fixation (N2 fixation). We applied a 15N tracer technique to assess the rate of release of Dissolved Organic Nitrogen (DON) from this cyanobacterium and compared those rates with rates of N2 fixation determined for the same assemblages at the same times of day. Rates of release of DON showed considerable variation within replicate experiments and were variable depending on time of day and duration of time course experiments. On average, rates of DON release were ca. 50% the rates of N2 fixation. We also fractionated the DON released by using ultrafiltration and found that 60 to 80% of the total Organic release was of the size class <10,000 Da. The release of these Organic compounds by Trichodesmium spp. is likely a significant source of new Nitrogen for the associated bacteria or the non-Nitrogen-fixing filaments of the Trichodesmium colonies.