Spectroscopic and Chromatographic Characterization of Wastewater Organic Matter from a Biological Treatment Plant

Spectroscopic and chromatographic changes in dissolved organic matter (DOM) characteristics of influent and treated sewage were investigated for a wastewater treatment plant (WWTP) with a biological advanced process. Refractory DOM (R-DOM) was defined as the dissolved organic carbon concentrations of the samples after 28-day incubation for this study. Specific UV absorbance (SUVA), hydrophobicity, synchronous fluorescence spectra and molecular weight (MW) distributions were selected as DOM characteristics. The percent distribution of R-DOM for the effluent was much higher than that of the influent, indicating that biodegradable DOM was selectively removed during the process. Comparison of the influent versus the effluent sewage revealed that SUVA, fulvic-like fluorescence (FLF), humic-like fluorescence (HLF), the apparent MW values were enhanced during the treatment. This suggests that more aromatic and humic-like compounds were enriched during the biological process. No significant difference in the DOM characteristics was observed between the original effluent (i.e., prior to the incubation) and the influent sewage after the incubation. This result suggests that the major changes in wastewater DOM characteristics occurring during the biological advanced process were similar to those for simple microbial incubation

Estimation of Biological Oxygen Demand and Chemical Oxygen Demand for Combined Sewer Systems Using Synchronous Fluorescence Spectra

Real-time monitoring of water quality for sewer system is required for efficient sewer network design because it provides information on the precise loading of pollutant to wastewater treatment facilities and the impact of loading on receiving water. In this study, synchronous fluorescence spectra and its first derivatives were investigated using a number of wastewater samples collected in sewer systems in urban and non-urban areas, and the optimum fluorescence feature was explored for the estimation of biochemical oxygen demand (BOD) and chemical oxygen demand (COD) concentrations of sewer samples. The temporal variations in BOD and COD showed a regular pattern for urban areas whereas they were relatively irregular for non-urban areas. Irrespective of the sewer pipes and the types of the areas, two distinct peaks were identified from the synchronous fluorescence spectra, which correspond to protein-like fluorescence (PLF) and humic-like fluorescence (HLF), respectively. HLF in sewer samples appears to be associated with fluorescent whitening agents. Five fluorescence characteristics were selected from the synchronous spectra and the first-derivatives. Among the selected fluorescence indices, a peak in the PLF region (i.e., Index I) showed the highest correlation coefficient with both BOD and COD. A multiple regression approach based on suspended solid (SS) and Index I used to compensate for the contribution of SS to BOD and COD revealed an improvement in the estimation capability, showing good correlation coefficients of 0.92 and 0.94 for BOD and COD, respectively

Impacts of Effluent and Stormwater Runoff Sources on Metal Lability and Bioavailability in Developed Streams

Urban streams receive Cu from both treated wastewater and stormwater runoff sources. Both sources have significant quantities of organic matter (OM), which is known to control Cu speciation and bioavailability. Individual and mixed water samples from wastewater treatment plant effluents, stormwater runoff, and streams from developed areas were characterized with respect to OM concentration and spectral properties and metal concentration and size distribution. In addition, asymmetric flow-field flow fractionation coupled to inductively coupled plasma mass spectrometry was used to measure concentration, size distribution and association of metals in the colloidal size range. Results reveal that Fe, Cu, Zn and Pb in the colloidal size range were mainly associated with the less than 5 nm, or less than 10 kDa size range. Cu was most strongly associated with OM, while Zn and Pb were mixed between Fe and OM. Effluent showed higher binding capacity for metals, while stormwater, even with higher OM concentrations showed more exchangeable metals. Upon mixing of source waters, colloidal metal concentrations and size distributions were conserved. Dissolved OM was either left intact or separated into small (0-650 Da), medium (650 Da-50 kDa), or large (50 kDa-0.45 μm) size fractions using tangential flow filtration (TFF). Conditional stability constants of the OM were determined using competitive ligand exchange-solid phase extraction. Metal ligand concentrations were determined from Cu titrations. Conditional stability constants of the whole effluent OM were 0.5 to 1 log unit higher than those of stormwater OM for both hydrophilic and hydrophobic OM (Hydrophilic: Log KCu-eff-OMf = 8.2±0.2, Log KCu-storm-OM = 7.5±0.3; hydrophobic OM: Log KCu-eff-OM = 8.9±0.4, Log KCu-storm-OM = 7.9±0.1). The stability constants of the source Hongwei Luan – University of Connecticut, 2016 OM were all higher than those of algae (Log KM-total = 6.3 and Log KM-intra = 6.8). Based on short-term uptake experiments, the results show there was 46% less total Cu uptake in the presence of effluent OM than stormwater OM, while intracellular Cu was about 25% less with effluent. This difference corresponded to the higher conditional stability constants measured for effluent OM than stormwater OM. We also found Cu mainly bound hydrophilic OM (80%) in effluent while it mainly bound hydrophobic OM (77%) in stormwater. Incorporating the conditional stability constants and metal ligand concentrations into an algal uptake model, the Cu uptake could be predicted. As for attachment to algal surfaces, stormwater OM promoted more accumulation of Cu on the algal surface, but this accounted for a small percentage of the total algal Cu content. Furthermore, there was a difference in Cu biouptake and stability constants between effluent and storm size fractions. For effluent OM, the Cu uptake and stability constants across size fractions were similar to the whole effluent. For stormwater OM the Cu stability constants were the lowest for the small size stormwater OM, resulting in more Cu uptake as stormwater OM size decreased. Differentiation between OM sources could lead to better predictions of metal uptake

Assessing hydraulic connection and dissolved organic matter in a karst landscape: Wellington, Australia

The objective of this study is to understand the association between the Bell River and alluvial and karst aquifers at Wellington, Australia. Two-dimensional resistivity imaging mapped the transition between the alluvium and karst. The water levels in caves, bores within the karst and the alluvium, and in the river were continuously measured. Water samples along the river, and from alluvial and karst monitoring bores and from the caves were collected. Water isotopic composition, chloride and DOC concentrations were determined, absorbance values were measured and fluorescence properties were characterised. The absorbance data were processed to provide the specific ultraviolet absorbance (SUVA) and spectral slopes. Parallel factor analysis (PARAFAC) was applied to discriminate fluorescent DOM components and to assess their dynamics in river and groundwater. The resistivity images delimited a dipping boundary between the low resistivity alluvium and the more resistive limestone, and delimit the water level in the aquifer. There are likely cavities that can act as potential pathways for groundwater flow, connecting Wellington karst aquifer with the alluvial aquifer and the river. Groundwater levels are dynamic and respond quickly to changes in the river stage, implying a strong hydraulic connection, and that the river is losing. The water stable isotope (δ18O and δ2H) and chloride data demonstrate a direct hydraulic connection between the river and groundwater. PARAFAC modelling revealed different models were necessary for river and groundwater samples, with component one of the groundwater model in the ‘peak T’ region, and of the river model in the ‘peak C’ region. Absorbance and fluorescence data suggest that sedimentary organic matter in the alluvium and karst is a major source of groundwater DOM, which is subsequently utilized by microbial activity. Additionally, there is a transition zone in the aquifer adjacent to the river (< 50 m) where DOM concentration, absorbance and fluorescence intensity rapidly decrease from the river to the aquifer, suggesting the groundwater near the river acts as a sink for the riverine organic matter during periods where the river is infiltrating the aquifer

Avaliação da tratabilidade de lixiviado de aterro sanitário combinado com esgoto sanitário em reator anaeróbio tipo UASB

Orientador: Prof. Dr. Miguel Mansur AisseTese (doutorado) - Universidade Federal do Paraná, Setor de Tecnologia, Programa de Pós-Graduação em Engenharia de Recursos Hídricos e Ambiental. Defesa : Curitiba, 29/03/2019Inclui referências: p. 189-211Resumo: Caracterizado por ser uma matriz aquosa complexa, o lixiviado de aterro sanitário pode apresentar riscos de poluição em corpos hídricos, se não gerenciado de forma adequada. Uma das opções é sua codisposição em Estações de Tratamento de Esgotos Sanitários. Contudo, estudos devem ser realizados para averiguar a viabilidade de tal prática, sobretudo, quanto ao comportamento da matéria orgânica do lixiviado bruto. O presente trabalho teve como objetivo a avaliação da tratabilidade de lixiviado de aterro sanitário combinado com esgoto sanitário em reator anaeróbio tipo UASB. As etapas da pesquisa foram, primeiramente caracterizar o lixiviado bruto por parâmetros físicos, químicos e biológicos tradicionais e por parâmetros coletivos específicos, como DQO inerte e matéria orgânica dissolvida (MOD). A segunda etapa consistiu em avaliar a influência do lixiviado adicionado ao esgoto sanitário (até 20 % v/v), na biodegradação anaeróbia, em reatores de bancada. Na terceira etapa foi avaliado o comportamento do reator tipo UASB (150 L), operado com TDH de 8 h, na codisposição do lixiviado, em porcentagens de 2%, 5% e 10%. Na quarta etapa foram avaliadas as modificações da MOD no tratamento em reator UASB e na quinta etapa foi avaliada a qualidade do lodo anaeróbio visando a disposição agrícola. Os resultados indicam que as amostras de lixiviados apresentaram características distintas entre as coletas, com relação DBO/DQO superior a 0,27, DQO inerte superior a 30% e nitrogênio amoniacal acima de 1792 mg L-1. Os ensaios de biodegradabilidade anaeróbia destacaram que relações volumétricas de lixiviado superiores a 5% podem interferir de forma significativo no tratamento. A avaliação qualitativa da MOD, no lixiviado, possibilitou monitorar a degradação e a alteração da matéria orgânica lábil, em função do tempo de armazenamento. Os resultados da codisposição, em reatores tipo UASB, demonstraram que o lixiviado não interferiu de forma significativa no tratamento do esgoto, com porcentagem de 2% e 5%, sendo as eficiências em termos de DQO de 53% e 49%, respectivamente. Contudo, para 10% de lixiviado, obteve-se remoção média de DQO de 37% devido a adição de possíveis substâncias tóxicas, como a amônia. Constatou-se elevados valores de cor verdadeira e SDT no efluente, reiterando necessidade de pós-tratamento. As análises espectroscópicas da MOD indicaram que a refratabilidade aumenta conforme maior porcentagem de lixiviado é adicionada. No efluente, de cada etapa, foi possível notar características tanto de matéria orgânica lábil, como refratária. A fluorescência pode ser usada na caraterização da MOD em efluentes e dar indícios da eficiência de remoção desses compostos, junto com os parâmetros COD, DQO e DBO, oferecendo um método complementar de avaliação. A adição de lixiviado com esgoto, por cerca de 2 anos, alterou as concentrações de substâncias inorgânicas no lodo anaeróbio e inviabilizou o uso agrícola, pois as concentrações de Zn resultaram acima aos valores estabelecidos nas resoluções brasileiras. Palavras chave: Codisposição, Espectroscopia, Lodo anaeróbio, Parâmetros coletivos específicos.Abstract: Characterized as a complex aqueous matrix, landfill leachate may present pollution risks in a hydrous body if not properly managed. One of the options is the codisposition of the leachate with sanitary sewage, although further studies should be carried out to ascertain the feasibility of such practice, especially concerning the behavior of the organic matter of the raw leachate in this treatment. The present thesis had the objective of evaluating the treatability of landfill leachate combined with sanitary sewage from anaerobic UASB reactor. The stages of the research were first to characterize the raw leachate through the physical, chemical and biological parameters and, through the specific collective parameters, as inert COD and dissolved organic matter (DOM). The second step was to assess the influence of the leachate added to sewage (up to 20% v/v), on anaerobic biodegradation, bench reactors. In the third step, the behavior of the UASB reactor (150 L) was evaluated, operating with 8 h DHT, in the leachate codisposition in sanitary sewage, in percentages of 2%, 5% and 10% v / v. The fourth step evaluated the modifications of the DOM in the anaerobic treatment in UASB reactor and the fifth stage, the quality of the anaerobic sludge was evaluated aiming the agricultural layout. The results indicated that the samples of leachates evaluated presented very different characteristics from one collection to another, with BOD/COD ratio above 0.27, inert COD of more than 30% and ammonia concentration of 1.792 mg L-1. The anaerobic biodegradability tests with raw leachate and sanitary sewage have highlighted that volumetric ratios higher than 5%, can interfere significantly in the treatment performance. The qualitative evaluation of the DOM, in the leachate, allowed monitoring the degradation and the alteration of the labile organic matter, as a function of storage time. The results of the codisposition, in UASB reactors, showed that the leachate did not significantly interfere in the treatment of sewage, with a percentage of 2% and 5%, with COD efficiencies of 53% and 49%, respectively. However, for the 10% leachate percentage, COD average removal was 37% due to the addition of possibly toxic substances, such as ammonia. High values of true color and TDS were observed in the effluent due to the addition of the leachate, observing the need for post-treatment of the effluent. The spectroscopic analyses of the DOM indicated that the retractability increases as a higher percentage of leachate are added. In the effluent, from each stage, it is possible to note the characteristics of both labile organic matter and refractory organic matter. Fluorescence can be used to characterize the DOM in effluents and provide evidence of the removal efficiency of these compounds, together with the DOC, COD and BOD parameters, offering a complementary method of evaluation. The addition of leachate with sewage in a UASB reactor, for about two years, altered the concentrations of inorganic substances in the anaerobic sludge and made agricultural use unfeasible, since the Zn concentrations are above the limits established in the Brazilian resolutions. Keywords: Codisposition, Spectroscopy, Anaerobic sludge, Specific collective parameters

The Use of COD, TOC, Fluorescence, and Absorbance Spectroscopy to Estimate Biochemical Oxygen Demand in Wastewater

All wastewater treatment facilities must obtain a National Pollution Discharge Elimination System (NPDES) permit, which regulates the quality of water that is discharged. Common to all NPDES permits is a limit on organic matter, as determined by the five-day biochemical oxygen demand (BOD5) test. More rapid methods, such as chemical oxygen demand (COD), total organic carbon (TOC), fluorescence, and absorbance spectroscopy are also capable of quantifying organic matter. Previous studies indicate it is possible to develop correlations between these parameters. This study explored the correlations using influent, primary clarifier effluent, and finished effluent samples from an operational wastewater treatment plant located in Nevada. It was concluded that COD could be used to estimate BOD5 for influent, primary clarifier effluent, and finished effluent. TOC could be used as a surrogate for finished effluent, but it was not suitable for influent or primary clarifier effluent. The relationship developed for fluorescence and BOD5 was nonlinear, presumably due to inner filter effect (IFE) interference. Power functions were developed for region I of the excitation emission matrix (EEM) and peak T (excitation=275 nm, emission=340 nm) that could be used to estimate BOD5 for finished effluent and primary clarifier effluent, but they were poor estimators for plant influent. Comparison of removal efficiencies indicated that TOC and fulvic-like fluorescence peaks increased in the primary clarifier, presumably due to the return of centrate that is sent back to the primary clarifier. The fluorescence removals indicated that over 80% of protein-like (typically associated with BOD5) fluorescence was removed during treatment and approximately half of humic- and fulvic-like fluorescence was removed during treatment. Quality control experiments indicated that holding the samples overnight biased the test results low, which was more pronounced when samples were held with headspace. Degradation likely occurs due to the biological consumption of organic matter that is occurring within the sample during the holding time