Total Organic Load Research Articles

Activated Persulfate and Hydrogen Peroxide Treatment of Highly Contaminated Water Matrices: A Comparative Study

The efficacy of Fe2+-activated persulfate (PS) and hydrogen peroxide (HP) treatment in total organic load and selected organic pollutants removal from different highly polluted industrial effluents was evaluated and compared. The studied wastewater samples involved a paint production wastewater (S1), phenolic wastewater (S2) and mature landfill leachate (S3). The coagulation proved an effective technique to pre-treat S1, and thus to reduce substantially the amount of chemicals required in the subsequent oxidation step. The Fenton treatment (HP/Fe2+) proved more effective S1 post-treatment technology than the PS/Fe2+ process and resulted in substantial COD and DOC removal as well as in considerable the BOD7/COD ratio increase. In the case of S2 and S3, the application of Fenton process also demonstrated higher total organic load removal efficacy than the PS/Fe2+ system. Conversely, the HP/Fe2+ oxidation was characterized by a temperature increase and excessive foam formation. The findings of this study provide valuable information for further full-scale applications of Fe2+-activated HP and PS based processes for the treatment of highly contaminated wastewater with the most effective concentrations of reagents used.

Trametes versicolor immobilized on rotating biological contactors as alternative biological treatment for the removal of emerging concern micropollutants

White rot fungi have been studied for the removal of micropollutants of emerging concern from wastewater during the last decade. However, several issues need to be overcome for its plausible implementation at full-scale installations such as the addition of supplementary substrates, the partial re-inoculation of fresh fungi or the use of extended hydraulic retention times. This work proposes the immobilization of Trametes versicolor on rotating biological contactors at bench scale (flowrates of 10 L/d and reactor capacity of 10 L) for the treatment of different urban wastewater. This type of bioreactor achieved remarkable reductions of the total organic carbon loading of the wastewater (70–75%) in a wide range of C:N and C:P ratios with limited addition of supplementary substrates, non-refreshment of the fungal biomass and only 1-day of hydraulic retention. The addition of gallic acid as quinone-like mediator and quelated iron and manganese complexes increased the removal of pharmaceutical micropollutants mediated by the so-called advanced bio-oxidation process. The immobilization of Trametes versicolor on rotating biological contactors also showed a remarkable stabilization of the fungi during the continuous treatment of different urban wastewater under non-sterile conditions. Thus, this system is a sound alternative for biological urban wastewater treatment with pharmaceutical removal because overcome all the problems usually associated with the water treatment technologies based on white rot fungi that makes difficult the scaling-up of the process and its implementation in full scale wastewater treatment plants.

Hydrothermal processing of Kraft lignin for carboxylic acid production

The present study describes, for the first time ever, the production of organic acids by hydrothermal treatments using Kraft lignin from black liquor as feedstock, analysing the effect of the temperature and the type of atmosphere. The presence of oxygen had a positive impact on the total amount of acids, particularly, at 70 bar and 210 °C, being formed 172.8 g of acids per kg of Chemical Oxygen Demand consumed after 120 min of treatment. Moreover, it generated a final reaction medium mainly composed of acids, which represented 81.8% of the remaining total organic load. On the contrary, the maximum generation under an inert atmosphere was 17% lower, being reached after 120 min at 70 bar and 190 °C. Furthermore, selecting the operating conditions could be a tool to obtain a certain distribution of acids, increasing the proportions of lactic and acetic acid in the final mix compared to malic and formic acid during the wet oxidation process, while the latter prevailed during the thermal hydrolysis.

Removal efficiencies of top-used pharmaceuticals at sewage treatment plants with various technologies

The presence of pharmaceuticals in wastewater and the environment has attracted growing public concern. Although studies have been performed to detect pharmaceuticals in wastewater effluents, little research has been conducted to assess the efficiency of pharmaceutical removal using different treatment technologies. To assess the removal efficiencies of pharmaceuticals in wastewater, samples from 22 municipal treatment plants in Nova Scotia and New Brunswick were analyzed for 12 commonly used pharmaceuticals and 2 primary metabolites. The medians of removal efficiencies for 9 technologies: aerated lagoon, extended aeration, facultative lagoon, membrane bioreactor, modified secondary, oxidation ditch, primary treatment, rotating biological contactor, and sequencing batch reactor technologies, were determined to be 98.0%, 96.4%, 98.2%, 99.8%, 68.4%, 99.0%, 3.0%, 81.3%, and 98.3%, respectively. The medians of removal efficiencies of individual pharmaceuticals were found from -14.4% to 100%. Primary treatment showed significant differences comparing to other treatment technologies. Very strong correlations of removal efficiencies were found between acetaminophen and warfarin, between cotinine and warfarin, between cotinine and paraxanthine, and between ramipril and atorvastatin. In general, there was no strong correlation of removal between pharmaceuticals and total organic waste load or total suspended solids.

Multivariate and multiobjective optimization of tannery industry effluent treatment using Musa sp flower extract in the coagulation and flocculation process

Several studies have focused in the tannery industry due to the high polluting potential of the effluent generated in leather processing; high concentrations of total chromium and organic load. However, the high costs attributed to the treatment of tanning residues explains why this material is not treated within the tannery industry. The extract from the flower of Musa sp, condensed and hydrolisable tanins, yet to be explored in literature was applied to remove organic matter from chemically enhanced primary treatment (CEPT) of total solids, turbidity and total chromium from a tanning industry and leather processing. The use of the flower extract of Musa sp. proposed in this study does not require flocculant polymers after the coagulation step. A central composite design response surface (CCD) was modelled by the factors: coagulant volume, pH and rotation. The optimization was performed according to the NBI algorithm in a mixed arrangement to determine optimal weights. The modeling from CCD and minimization of Global Standard Error determines the optimized conditions, turbidity removal, total cromium, hexavalent chromium and trivalente chromium of 78% and 65.4%, 39.43% and 61.02%, respectively, increasing the biodegradability from the ratio biochemical oxygen demand (COD) and chemical oxygen demand (COD) of 0.12–0.63.

Contribution of sea cucumber Holothuria tubulosa on organic load reduction from fish farming operation

An investigation was carried out in the field and in the laboratory in order to evaluate the contribution of sea cucumber Holothuria tubulosa on organic load reduction from fish farming in the Eastern Mediterranean. Five experimental cages and three double systems of seawater aquaria were used for this purpose. The mean reduction of OM and OC was 30.73% and 58.58%, respectively. Moreover, the mean absorption efficiency of OM and OC during transit in the intestine of H. tubulosa was 43.40% and 54.65%, respectively. One-way ANOVA indicated significant differences on OM and OC accumulation rate between holothurians and control (p < .05). The results indicated that the feeding activity of H. tubulosa seemed to reduce the total organic load of the fish farm biodeposits, demonstrating their potential as an important organic-reducing component for the sustainability of aquaculture in the Mediterranean region.

Semi-volatile and highly oxygenated gaseous and particulate organic compounds observed above a boreal forest canopy

Abstract. We present hourly online observations of molecular compositions (CxHyOzN0−1) and abundances of oxygenated organic species in gas and submicron particle phases from April to June of 2014 as part of the Biogenic Aerosols-Effects on Cloud and Climate (BAECC) campaign. Measurements were made using the Filter Inlet for Gases and AEROsols coupled to a high-resolution time-of-flight iodide-adduct ionization mass spectrometer (FIGAERO-CIMS) located atop a 35 m tall tower, about 10 m above a boreal forest canopy at the SMEAR II research station in Hyytiälä, Finland. Semi-volatile and highly oxygenated multifunctional (HOM) organic species possessing from 1 up to 20 carbon atoms, and with as few as 2 and as many as 16 oxygen atoms, were routinely observed. Utilizing non-negative matrix factorization, we determined that &gt; 90 and &gt; 99 % of the organic mass in the gas and particle phases, respectively, exhibited one of three distinct diel trends: one in which abundances were enhanced at daytime, another in the early morning hours, and thirdly during nighttime. Particulate organic nitrates contributed ∼ 35 % to the total organic aerosol mass loading at night during BAECC, much higher than observed by the same instrument package at a mixed-deciduous forest site in the southeastern US that experienced higher nighttime concentrations of nitrogen oxides. Unique HOM monomers (defined here as those with 10 carbon and 7 or more oxygen atoms) and dimers (at least 16 carbon atoms), with and without a nitrogen atom, were found in most of the three subgroups of both phases. We show the potential to connect these groupings of compounds based on their distinct behavior in time to the expected chemical conditions (biogenic VOC precursor, oxidant type, etc.) responsible for their production. A suite of nitrated dimer-like compounds was detected in both the gas and particle phases, suggesting a potential role for the formation of low-volatility organics from NO3-radical-driven, as well as daytime NO-influenced, monoterpene chemistry.

METHANE PRODUCTION FROM CASSAVA STARCH WASTEWATER IN PACKED-BED REACTOR AND CONTINUOUS FLOW

ABSTRACT The aim of this study was to evaluate the behavior of an anaerobic reactor of packed-bed and continuous flow, in relation to the biogas and methane production and the removal of organic load, from the wastewater of cassava starch extraction. For this purpose, were tested, in a reactor with a useful volume of 2.82 L and support mean of polypropylene filled with polyethylene foam, the organic loading rate (OLR) of 2.5, 5.0, 8.0 and 10.0 g L-1d-1. It was evaluated the removal of COD, the pH, the VA/TA ratio, the biogas and the methane production. It was concluded from this study that it is possible to produce biogas with methane percentages higher than 80% (maximum) and remove the organic load more than 90% under the tested conditions. In relation to stability, the reactor can be considered stable for the parameters, pH, the relationship between volatile acidity and total alkalinity and organic load removal. The best results in relation to the average volumetric biogas production (0.174 and 0.311 L g COD-1) were obtained for the higher organic loading rate (of 8 and 10 g L-1d-1, respectively) and the observed tendency is that with the increase of the organic loading rate, the specific biogas production will increase as well as the specific production of methane.

Assessing sedimentation in a temperate dystrophic lake in the NE Atlantic seaboard region

Organic materials deposited in lacustrine environments can be derived from both aquatic and terrestrial ecosystems, and can serve as valuable indicators of catchment and in-lake ecological changes over time. However, spatial and temporal variation in the deposition of these materials within a lake basin will influence the interpretation of these sediment deposits. In this study, materials deposited in suspended sediment traps and basin sediments in Lough Feeagh, a temperate coastal humic lake, show variations in organic matter, total organic carbon and nitrogen loads, algal pigment concentrations and diatom assemblages. Sediment trap samples from three locations along with adjacent surface sediment cores show a clear north–south (inlet to outlet) gradient. C/N ratios reflected a mixture of algal and land-derived organic matter with a major peat influence, and comparisons between sediment trap and surface sediment assemblages revealed pigment and diatom assemblages influenced by lake-basin position and water depth. While some coherency between trap and sediment samples was apparent a more complicated biological response is demonstrated along with reduced water clarity in recent years thus highlighting the implications of increased allochthonous imputs for biological and biogeochemical processes in oligo-humic aquatic systems.

Complex patterns of catchment solute–discharge relationships for coastal plain rivers

AbstractRiverine solute versus discharge (C–Q) relationships provide information about the magnitude and dynamics of material fluxes from landscapes. We analysed long‐term patterns of C–Q relationships for 44 rivers in Florida across a suite of geogenic, nutrient, and organic solutes and investigated land cover, watershed size, and surficial geology as controls on these patterns. Solute concentrations generally exhibited far less variability than did discharge, with coherent solute‐specific behaviours repeated across watersheds. Geogenic solutes generally diluted with increasing discharge, whereas organic solutes generally enriched; patterns for nutrients were highly variable across watersheds, but on average exhibited chemostasis. Despite strong evidence of both geologic and land cover controls on solute flow‐weighted concentrations, these variables were poor predictors of C–Q slopes (β) or relative coefficients of variation (CVC:CVQ). CVC:CVQ generally increased with watershed size, and wetland area appeared to influence C–Q patterns for base cations and organic solutes. Perhaps most importantly, we observed significant slope breaks in C–Q association in approximately half of our observations, challenging the generality of using single power functions to describe catchment solute export patterns. For all solutes except phosphorus (P), C–Q slopes decreased above statistically identified breaks (slopes for P increased), with breaks consistently at or near median flow (i.e., 50% flow exceedance probability). This common pattern significantly impacts solute load estimates; failing to account for slope breaks overestimates nitrate and total organic carbon loads as much as 125% and underestimates P loads as much as 35%. In addition to challenging generic power‐law characterization of C–Q relationships for these coastal plain rivers, and exploring the load estimate consequences thereof, our study supports emerging insights about watershed hydrochemical behaviours across a wide array of solutes.

Potential of phosphatases for express assessment of self-purification at different types of pollution in running waters

Abstract The potential of an express enzymological indicator – phosphatase activity index (PAI) – for assessment of different types of pollution and self-purification potential in running waters was evaluated for three river subcatchments, representative for different ecological situations and impacts. According to the values of correlation coefficients, a significant positive correlation existed among PAI and total microbial count, organic loading and phosphate concentrations. The enzyme activity is useful tool for early identification of risks from point discharge of different wastewaters (treated or non-treated). The role of PAI as an indicator is significant at case of disinfection after treatment of wastewaters in treatment plant – the aquatic microbial community at the discharge point is suppressed but not at a functional level. The results allow classical microbiological and chemical parameters (state variables) to be related directly to the dynamics of the transformation processes by functional variable – PAI.

The control of small and medium sized public wastewater treatment plants in the Veneto region (North Italy): general situation, critical issues and case studies

Abstract Water bodies' quality objectives are defined in accordance with the Urban Wastewater Treatment Directive 91/271/EEC and the Water Framework Directive 2000/60/EC. For regulation and control of small-sized waste-water treatment plants (WWTPs), responsibility is delegated in Italy to Regional Authorities that fix specific regulations (Water Protection Plan WPP included in the River Basin Management Plan RBMP) in collaboration with the District Authorities. Small (&amp;lt;2,000 population equivalent – PE) and medium sized (2,000–10,000 PE) WWTPs in the Veneto Region (North Italy) represent about 10% of the total organic load (Imhoff systems included). This also comprises some industrial discharges. Due to the urban sprawl, plants are spread over the regional territory. In the Veneto Region, data from the official census reveals there are n. 248 plants under 2,000 PE and 135 plants in 2,000–10,000 range while the total number of authorized plants is 488 for a total potentiality of 9,141,572 PE. Data from institutional controls performed by the Veneto Regional Environmental Agency (ARPAV) on WWTPs has been recovered for all the WWTPs with up to 10,000 PE in the provinces of Venice, Treviso and Vicenza (for a total of 306,118 PE and for a total of 164 plants) in the period 2008–2015 and elaborated to assess critical parameters and plants. The general situation, critical issues and case studies have been presented and discussed. Organic load, nutrients and Escherichia coli are the most critical parameters considering the regional WPP.

Performance of Two Bioswales on Urban Runoff Management

This study evaluated the effectiveness of two bioswales eight years after construction in Davis, California. The treatment bioswale measured 9 m × 1 m × 1 m (L × W × D). Engineered soil mix (75% native lava rock and 25% loam soil) replaced the native loam soil. Four Red Tip Photinia (Photinia × fraseri Dress) trees and two Blueberry Muffin Hawthorn (Rhaphiolepis umbellata (Thunb.) Makino) shrubs were planted in the bioswale. Runoff flowed into the bioswale from an adjacent 171 m2 panel of turf grass. An identically sized control bioswale consisting of non-disturbed native soil was located adjacent to the treatment bioswale. Surface runoff quantity and quality were measured during three experiments with different pollutant loads. When compared to the control, the treatment bioswale reduced surface runoff by 99.4%, and reduced nitrogen, phosphate, and total organic carbon loading by 99.1%, 99.5%, and 99.4%, respectively. After eight years, tree growth characteristics were similar across both sites.

Optimization of mixing ratio of ammoniated rice straw and food waste co-digestion and impact of trace element supplementation on biogas production

The anaerobic co-digestion of biomass waste, a promising process of reusing resources, is capable of improving methane production. However, the characteristics and composition of fermenting raw material negatively influence the efficiency of methane production. Optimization experiments were systematically performed in this study through anaerobic co-digestion with urea-ammoniated rice straw (UARS) and food waste (FW) as co-substrates. Anaerobic co-digestion of UARS and FW in biogas production under mesophilic conditions (35 °C) was investigated in a 1 L enclosed triangular flask with a total organic load of 6 g volatile solids (VS)/L. The optimal mixing ratio of UARS to FW was close to 1:3, and the methane yield increasing by 8.83% compared with the sole substrate. Furthermore, based on the optimization ratio, supplementation of cobalt (Co) and nickel (Ni) on co-digestion were significantly superior to that of a single element. Additionally, kinetic analysis indicated that trace element remarkably facilitated the reaction rate of co-digestion. Noteworthy, the addition of Co, Ni, and the combination of Co and Ni achieved very significant (p < 0.01) improvement of 6.45, 8.36, and 13.65%. Meanwhile, Ni was substantially promoted the removal rate of VS, enhanced the operational stability of co-digestion and increased the methane content significantly.

Greywater characterization and loadings – Physicochemical treatment to promote onsite reuse

Greywater is the wastewater produced in bathtubs, showers, hand basins, kitchen sinks, dishwashers and laundry machines. Segregation of greywater and blackwater and on site greywater treatment in order to promote its reuse for toilet flushing and/or garden irrigation is an interesting option especially in water deficient areas. The objective of this study was to characterize the different greywater sources in Greek households and to evaluate the performance of alternative physicochemical treatment systems to treat several types of greywater. Based on the results average daily greywater production was equal to 98 L per person per day and accounts for approximately 70–75% of the total household wastewater production (135 L per person per day). Among the different sources, laundry and kitchen sink are the main contributors to the total greywater load of organic carbon, suspended solids and surfactants, whereas dishwasher and bathroom greywater are the main sources of phosphorus and endocrine disrupting chemicals respectively. Depending on sources, greywater accounts for as low as 15% of the total wastewater load of organic carbon (in the case of light greywater sources), to as high as 74% of the total load organic load (in the case of the heavy greywater sources). On the other hand, the nutrients load of greywater is limited. The application of a physical treatment system consisting of coagulation, sedimentation, sand filtration, granular activated carbon filtration and disinfection can provide for a final effluent with high quality characteristics for onsite reuse, especially when treating light greywater.

Bio-recalcitrant pollutants removal from wastewater with combination of the Fenton treatment and biological oxidation

The implementation of the Fenton treatment as an intermediate step in combined technological scheme for the removal of bio-recalcitrant organic pollutants from industrial effluents is proposed in this study. The treatment schemes for the purification of three heavily polluted wastewaters originated from a municipal non-hazardous waste landfill, industrial hazardous waste landfill and plywood manufacturing factory were developed. Accordingly, the wastewaters were subjected to aerobic biological treatment (BIO) combined with the Fenton process with the final aim of establishing universally applicable treatment scheme.The study demonstrated that the Fenton oxidation can be successfully included in the high-strength wastewater treatment scheme as an intermediate treatment step for the removal of bio-recalcitrant organics fraction. The elaborated BIO-Fenton-BIO approach was found to be cost-effective for the total organic load reduction and for the selected specific pollutants removal from the studied high-strength wastewaters. Consequently, it could be considered suitable for broader practical implementation.

Spatio-temporal variability of dissolved organic nitrogen (DON), carbon (DOC), and nutrients in the Nile River, Egypt.

Increases in human activity have resulted in enhanced anthropogenic inputs of nitrogen (N) and carbon (C) into the Nile River. The Damietta Branch of the Nile is subject to inputs from industrial, agricultural, and domestic wastewater. This study investigated the distribution and seasonality of dissolved organic nitrogen (DON), dissolved organic carbon (DOC), and nutrients in the Nile Damietta Branch. Water samples were collected from 24 sites between May 2009 and February 2010. Dissolved organic nitrogen concentrations averaged 251±115μg/l, with a range of 90.2-671μg/l, and contributed 40.8±17.7% to the total dissolved nitrogen (TDN) pool. Relative to autumn and winter, DON was a larger fraction of the TDN pool during spring and summer indicating the influence of bacterioplankton on the nitrogen cycle. Concentrations of DOC ranged from 2.23 to 11.3mg/l with an average of 5.15±2.36mg/l, reflecting a high organic matter load from anthropogenic sources within the study area, and were highest during autumn. Higher values of biochemical oxygen demand (BOD), chemical oxygen demand (COD), DON, nitrate, and phosphate occurred downstream of the Damietta Branch and were probably due to anthropogenic inputs to the Nile from the Damietta district. A bacterial incubation experiment indicated that 52.1-95.0% of DON was utilized by bacteria within 21days. The decrease in DON concentration was accompanied by an increase in nitrate concentration of 54.8-87.3%, presumably through DON mineralization. Based on these results, we recommend that water quality assessments consider DON and DOC, as their omission may result in an underestimation of the total organic matter load and impact.

Composition and temporal stability of turf sediments on inner-shelf coral reefs

Elevated sediment loads within the epilithic algal matrix (EAM) of coral reefs can increase coral mortality and inhibit herbivory. Yet the composition, distribution and temporal variability of EAM sediment loads are poorly known, especially on inshore reefs. This study quantified EAM sediment loads (including organic particulates) and algal length across the reef profile of two bays at Orpheus Island (inner-shelf Great Barrier Reef) over a six month period. We examined the total sediment mass, organic load, carbonate and silicate content, and the particle sizes of EAM sediments. Throughout the study period, all EAM sediment variables exhibited marked variation among reef zones. However, EAM sediment loads and algal length were consistent between bays and over time, despite major seasonal variation in climate including a severe tropical cyclone. This study provides a comprehensive description of EAM sediments on inshore reefs and highlights the exceptional temporal stability of EAM sediments on coral reefs.

Control factors and scale analysis of annual river water, sediments and carbon transport in China.

Under the context of dramatic human disturbances on river system, the processes that control the transport of water, sediment, and carbon from river basins to coastal seas are not completely understood. Here we performed a quantitative synthesis for 121 sites across China to find control factors of annual river exports (Rc: runoff coefficient; TSSC: total suspended sediment concentration; TSSL: total suspended sediment loads; TOCL: total organic carbon loads) at different spatial scales. The results indicated that human activities such as dam construction and vegetation restoration might have a greater influence than climate on the transport of river sediment and carbon, although climate was a major driver of Rc. Multiple spatial scale analyses indicated that Rc increased from the small to medium scale by 20% and then decreased at the sizable scale by 20%. TSSC decreased from the small to sizeable scale but increase from the sizeable to large scales; however, TSSL significantly decreased from small (768 g·m−2·a−1) to medium spatial scale basins (258 g·m−2·a−1), and TOCL decreased from the medium to large scale. Our results will improve the understanding of water, sediment and carbon transport processes and contribute better water and land resources management strategies from different spatial scales.

Teleconnection of Instream Total Organic Carbon Loads with El Niño Southern Oscillation (ENSO), North Atlantic Oscillation (NAO), and Pacific Decadal Oscillation (PDO)

<abstract> <b>Abstract.</b> Recently, total organic carbon (TOC) load has attracted a great deal of attention from water quality managers because it can form disinfection byproducts (DBP) during chlorination of drinking water. TOC loads in streams are generally affected by the hydrologic characteristics of a basin. In addition to the basin characteristics, hydrologic characteristics are affected by climate variability associated with a number of the oceanic and atmospheric phenomena that operate at seasonal to multidecadal time scales. Consideration of these large-scale climate phenomena, such as the El Niño Southern Oscillation (ENSO), North Atlantic Oscillation (NAO), and Pacific Decadal Oscillation (PDO), are important for water quality managers because they can provide additional information for reducing TOC loads (and hence potential for DBP formation) in the drinking water supply. The objective of this study was to see if teleconnections exist between ENSO, NAO, PDO, and TOC loads. This study was conducted in the Big Creek watershed in southern Alabama in a series of steps. In the first step, model-simulated TOC loads were used to understand the effect of climate on TOC loads while keeping the land use and anthropogenic effects constant. In the second step, wavelet analysis, including cross wavelet analysis and wavelet coherence, was conducted to examine the correlation of ENSO, NAO, and PDO with TOC load in a time and frequency space. Analysis indicated that the common period of oscillations of various climate signals with TOC loads was detected even though NAO and PDO are decadal phenomena. Further, we examined the effects of ENSO, NAO, and PDO on large TOC loads using ten possible combinations of climate signals. TOC loads in El Niño winters and springs were significantly higher than in La Niña winters and springs, especially when ENSO was modulated with high (positive) NAO and high (positive) PDO. Similarly, TOC loads in El Niño or La Niña, occurring concurrently with high PDO and high NAO, were higher than TOC loads in neutral periods occurring concurrently with low (negative) PDO and low (negative) NAO. Interestingly, TOC loads in the La Niña phase were significantly higher than in the El Niño phase from August to October, especially when La Niña was modulated with high PDO and high NAO. Quantifying instream TOC loads with various climatic conditions is helpful for monitoring TOC loads and devising control measures.