Application of improved rapid mixing for enhanced removal of dissolved organic matter and DBPFP (disinfection by-product formation potential) control

2006 ◽  
Vol 6 (1) ◽  
pp. 49-57 ◽  
Author(s):  
H.C. Kim ◽  
S. Lee ◽  
S.J. Byun ◽  
M.J. Yu
Keyword(s):  
Organic Matter ◽  
Product Formation ◽  
Turbidity Removal ◽  
Rapid Mixing ◽  
Potential Control ◽  
Coagulant Dosage ◽  
Uniform Dispersion ◽  
Hydrophilic Fraction ◽  
The Difference ◽  
Hydrophobic Fraction

Dispersion of metal coagulant should be completed in a fraction of a second before the metal hydroxide precipitate has formed. For this reason, so-called pump diffusion flash mixing (PDFM) has been proposed, and PDFM is one reasonable method to quickly disperse the hydrolyzing metal salts. In this study, we attempt to understand the difference of removal characteristics of natural organic matter (NOM) between PDFM and conventional rapid mixing (CRM) in a water treatment system, and to enhance the removal of NOM through the improved mixing process. Dissolved organic carbon (DOC) and turbidity removal by PDFM was higher than those by CRM, while specific ultraviolet absorbance (SUVA) of treated water by PDFM was higher than that by CRM. NOM was more effectively removed by PDFM compared to CRM due to quick and uniform dispersion of coagulants. Though the hydrophilic fraction found as major faction in bulk NOM from Han River water is enriched in haloacetic acid precursor sites as compared to hydrophobic fraction, the hydrophilic fraction was more effectively removed by PDFM rather than CRM. Therefore, PDFM is effective and innovative process in reduction of DOC and DBPFPs as well as turbidity, and requires lower coagulant dosage compared to CRM.

scholarly journals Treatment of highly turbid water in disaster conditions using coagulation-flocculation process: modeling and optimization

2020 ◽  
Vol 55 (4) ◽  
pp. 358-369
Author(s):  
Danial Nayeri ◽  
Seyyed Alireza Mousavi
Keyword(s):  
Quadratic Model ◽  
Maximum Efficiency ◽  
Turbid Water ◽  
Turbidity Removal ◽  
Rapid Mixing ◽  
Coagulant Dosage ◽  
Slow Mixing ◽  
The Impact ◽  
Central Composite ◽  
Sedimentation Time

Abstract In the present research, the coagulation-flocculation (CF) process was used to eliminate highly turbid water in disaster conditions. To better understand the efficiency of the system, the impact of various numerical factors namely; initial turbidity (10–350 NTU), pH (5–9), coagulant dosage (50–250 mg/L), rapid mixing (120–280 rpm), slow mixing (30–50 rpm), and sedimentation time (10–50 min) were optimized through the central composite design (CCD) under response surface methodology (RSM). Based on analysis of variance (ANOVA), the quadratic model was more suitable for the dataset with R2 = 0.85 for removing turbidity. Moreover, the results of the present study revealed that the highest turbidity removal (99.14%) was observed at pH (9), alum dosage (50 mg/L), initial turbidity (350 NTU), rapid mixing (280 rpm), slow mixing (50 rpm), and sedimentation time (50 min). Furthermore, the residual turbidity at the maximum efficiency of the system was 3 NTU.

The control of disinfection by-products precursors by advanced methods of water treatment

2018 ◽  
Vol 18 (6) ◽  
pp. 1906-1914
Author(s):  
Mariola Rajca ◽  
Agnieszka Włodyka-Bergier ◽  
Michał Bodzek
Keyword(s):  
Organic Matter ◽  
Water Treatment ◽  
Natural Organic Matter ◽  
Membrane Processes ◽  
Lower Affinity ◽  
Treatment Processes ◽  
Hydrophilic Fraction ◽  
Specific Potential ◽  
Hydrophobic Fraction ◽  
By Products

Abstract In the article, the results of the research on reactivity of natural organic matter in regard to disinfection by-products, specifically trihalomethanes (THM) formation, with the use of model waters, are discussed. Additionally, the evaluation of different processes used in water treatment, i.e. photocatalysis, MIEX®DOC and membrane processes, is made. It was found that the affinity of particular natural organic matter compounds to form chlorination by-products could be arranged in a series: hydrophobic fraction (HA) > hydrophilic fraction (FA). The applied treatment processes efficiently decreased the concentration of disinfection by-products (DBPs) precursors and characterized with different removal mechanisms. Water treated by means of photocatalysis (specific potential of ∑THM was 30 μg/mg dissolved organic carbon (DOC) for HA and 12 μg/mg DOC for FA) revealed lower affinity to form chlorination by-products in comparison with water undergone to MIEX®DOC process (specific potential of ∑THM was 38 μg/mg DOC for HA and 29 μg/mg DOC for FA). Moreover, combination of those methods with membrane processes efficiently reduced DBPs formation potential. In nanofiltration effluents DBPs potential were very low and equalled to 50 μg/L for HA and 15 μg/L for FA.

Application of O3/GAC process for advanced and selective removal of natural organic matter from conventionally treated water

2006 ◽  
Vol 6 (2) ◽  
pp. 101-108 ◽  
Author(s):  
H.C. Kim ◽  
M.J. Yu ◽  
J.Y. Koo ◽  
S. Lee
Keyword(s):  
Organic Matter ◽  
Natural Organic Matter ◽  
Rapid Decrease ◽  
Uv Absorbance ◽  
Ultraviolet Absorbance ◽  
Carbon Adsorption ◽  
Haloform Reaction ◽  
Hydrophilic Fraction ◽  
Demonstration Plant ◽  
Hydrophobic Fraction

A demonstration plant consisted of ozone/granular activated carbon (GAC) was operated using sand filtered water as an influent to study the feasibility for introduction of an advanced water treatment. In ozonating the sand filtered water, dissolved organic carbon (DOC) slightly increased at an ozone dose of less than 1.0 mg O3/mg C, and the largest DOC reduction was exhibited at 1.0 mg O3/mg C. As ozone dosage increased from 1.0 to 5.0 mg O3/mg C, DOC decreased no more, whereas UV absorbance at 254 nm gradually decreased with increasing ozone dosage. The hydrophobic fraction in natural organic matter (NOM) was considered as a predominant reactant from the result of a rapid decrease in specific ultraviolet absorbance (SUVA). Since the specific reaction sites in the NOM molecule for haloform reaction were attacked by ozonation, the disinfection by-product (DBP) formation potentials could be reduced. The hydrophobic fraction decreased from 36.3% to 28.7% by ozonation and then decreased to 24.2% through carbon adsorption. The hydrophilic fraction changed only by 1.0% during ozonation, while it decreased by 28.3% through carbon adsorption. Therefore, ozonation followed by carbon adsorption is an acceptable process for the reduction of latent risk through selective oxidation and adsorption of different NOM fractions.

Soil stripping and replacement for the rehabilitation of bauxite-mined land at Weipa. I. Initial changes to soil organic matter and related parameters

Soil Research ◽  
2000 ◽  
Vol 38 (2) ◽  
pp. 345 ◽  
Author(s):  
G. D. Schwenke ◽  
D. R. Mulligan ◽  
L. C. Bell
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Field Experiments ◽  
Surface Soil ◽  
Soil Disturbance ◽  
Microbial Biomass C ◽  
Low Grade ◽  
Double Pass ◽  
Organic C ◽  
The Difference

At Weipa, in Queensland, Australia, sown tree and shrub species sometimes fail to establish on bauxite-mined land, possibly because surface-soil organic matter declines during soil stripping and replacement. We devised 2 field experiments to investigate the links between soil rehabilitation operations, organic matter decline, and revegetation failure. Experiment 1 compared two routinely practiced operations, dual-strip (DS) and stockpile soil, with double-pass (DP), an alternative method, and subsoil only, an occasional result of the DS operation. Other treatments included variations in stripping-time, ripping-time, fertiliser rate, and cultivation. Dilution of topsoil with subsoil, low-grade bauxite, and ironstone accounted for the 46% decline of surface-soil (0–10 cm) organic C in DS compared with pre-strip soil. In contrast, organic C in the surface-soil (0–10 cm) of DP plots (25.0 t/ha) closely resembled the pre-strip area (28.6 t/ha). However, profile (0–60 cm) organic C did not differ between DS (91.5 t/ha), DP (107 t/ha), and pre-strip soil (89.9 t/ha). Eighteen months after plots were sown with native vegetation, surface-soil (0–10 cm) organic C had declined by an average of 9% across all plots. In Experiment 2, we measured the potential for post-rehabilitation decline of organic matter in hand-stripped and replaced soil columns that simulated the DS operation. Soils were incubated in situ without organic inputs. After 1 year’s incubation, organic C had declined by up to 26% and microbial biomass C by up to 61%. The difference in organic C decline between vegetated replaced soils (Expt 1) and bare replaced soils (Expt 2) showed that organic inputs affect levels of organic matter more than soil disturbance. Where topsoil was replaced at the top of the profile (DP) and not ploughed, inputs from volunteer native grasses balanced oxidation losses and organic C levels did not decline.

scholarly journals Temperature and UV light affect the activity of marine cell-free enzymes

2017 ◽  
Vol 14 (17) ◽  
pp. 3971-3977 ◽  
Author(s):  
Blair Thomson ◽  
Christopher David Hepburn ◽  
Miles Lamare ◽  
Federico Baltar
Keyword(s):  
Organic Matter ◽  
Extracellular Enzymes ◽  
Elevated Temperatures ◽  
Uv Light ◽  
Control Mechanisms ◽  
Potential Control ◽  
Control Factors ◽  
Rate Limiting Step ◽  
Ocean Environment ◽  
First Time

Abstract. Microbial extracellular enzymatic activity (EEA) is the rate-limiting step in the degradation of organic matter in the oceans. These extracellular enzymes exist in two forms: cell-bound, which are attached to the microbial cell wall, and cell-free, which are completely free of the cell. Contrary to previous understanding, cell-free extracellular enzymes make up a substantial proportion of the total marine EEA. Little is known about these abundant cell-free enzymes, including what factors control their activity once they are away from their sites (cells). Experiments were run to assess how cell-free enzymes (excluding microbes) respond to ultraviolet radiation (UVR) and temperature manipulations, previously suggested as potential control factors for these enzymes. The experiments were done with New Zealand coastal waters and the enzymes studied were alkaline phosphatase (APase), β-glucosidase, (BGase), and leucine aminopeptidase (LAPase). Environmentally relevant UVR (i.e. in situ UVR levels measured at our site) reduced cell-free enzyme activities by up to 87 % when compared to controls, likely a consequence of photodegradation. This effect of UVR on cell-free enzymes differed depending on the UVR fraction. Ambient levels of UV radiation were shown to reduce the activity of cell-free enzymes for the first time. Elevated temperatures (15 °C) increased the activity of cell-free enzymes by up to 53 % when compared to controls (10 °C), likely by enhancing the catalytic activity of the enzymes. Our results suggest the importance of both UVR and temperature as control mechanisms for cell-free enzymes. Given the projected warming ocean environment and the variable UVR light regime, it is possible that there could be major changes in the cell-free EEA and in the enzymes contribution to organic matter remineralization in the future.

An assessment of the quality of forage from its cell-wall content and amount of cell wall digested

1972 ◽  
Vol 78 (3) ◽  
pp. 355-362 ◽  
Author(s):  
K. W. Moir
Keyword(s):  
Cell Wall ◽  
Organic Matter ◽  
Ammonium Oxalate ◽  
Physical Structure ◽  
Tropical Species ◽  
Average Amount ◽  
Lignin Concentration ◽  
Digestible Organic Matter ◽  
The Difference

SUMMARYGrasses and legumes comprising poor to good quality temperate and tropical species were fed to either cattle or sheep in 36 digestibility experiments. Cell wall in these forages was the ash-free and protein-free residue after sequential extraction with acidpepsin, organic solvents and either water for grasses or ammonium oxalate for legumes. The average amount of cell wall digested per 100 g forage OM was 40·0±0·59 g in grasses and 19·8±1·85 g in legumes. It was considered that within grasses and within legumes the physiology of ruminant digestion, rather than forage quality, was the main determinant of the average amount of cell wall digested and the difference between grasses and legumes was due to interaction of the ruminant digestion process with the physical structure of the cell wall. Of forage factors governing variation about the physiological average, the total cell wall had some effect on the amount of cell wall digested, but the lignin concentration in the cell wall had no effect.Among grasses and legumes the average, apparently undigested, protein-free non-cell-wall component was 6·2±0·13 g per 100 g forage OM. This component and digestible protein relative to total protein varied among different sets of data. It was concluded that only the component of digestible organic matter which was governed by the relative proportions of cell walls and cellular contents was predictable from chemical composition. It was considered that selection in plant breeding should be based on both digestible cell wall and cell-wall content instead of digestible organic matter.

Evaluation of wastewater characterization methods

2005 ◽  
Vol 52 (10-11) ◽  
pp. 61-68 ◽  
Author(s):  
E.-H. Choi ◽  
B. Klapwijk ◽  
A. Mels ◽  
H. Brouwer
Keyword(s):  
Organic Matter ◽  
Organic Compounds ◽  
Nitrate Concentration ◽  
Characterization Methods ◽  
Biochemical Characteristics ◽  
Organic Components ◽  
N Removal ◽  
Curve Fit ◽  
The Difference

Wastewater contains various organic components with different physical and biochemical characteristics. ASM No. 1 distinguishes two categories of biodegradable organic matter in wastewater, rapidly and slowly biodegradable. In general there are two methods for wastewater characterization: based on filtration in combination with a long-term BOD test or based on a respirogram. By comparing both approaches, we showed that in wastewater three categories of organic compounds with different biodegradation rates can be distinguished. These categories are referred to as readily biodegradable, rapidly hydrolysable and slowly hydrolysable organic matter. The total biodegradable COD can be found from a long-term BOD-test combined with a curve-fit and the readily biodegradable and rapidly hydrolysable from a respirogram. The slowly hydrolysable is the difference between total biodegradable COD and the sum of readily biodegradable and rapidly hydrolysable COD. Simulation with characterization based on filtration for a pre-anoxic reactor with a certain N-removal compared with the N-removal of the same plant with wastewater according to the modified characterization shows different results of each wastewater, especially with regard to the effluent nitrate concentration.

Removal of Humic Substances by Coagulation

1999 ◽  
Vol 40 (9) ◽  
pp. 47-54 ◽  
Author(s):  
C.R. O’Melia ◽  
W.C. Becker ◽  
K.-K. Au
Keyword(s):  
Water Quality ◽  
Organic Matter ◽  
Complex Formation ◽  
Natural Organic Matter ◽  
Divalent Cations ◽  
Water Source ◽  
Quality Characteristic ◽  
Oxide Surfaces ◽  
Water Quality Characteristic ◽  
Coagulant Dosage

Measurements and modeling of the adsorption of natural organic matter (NOM) on oxide surfaces are presented and compared. Agreement is good and supports the view that the adsorption of NOM on oxides depends significantly on complex formation reactions between specific sites on oxide surfaces and functional groups on the NOM. Coagulant requirements can and often are set by the total organic carbon (TOC) concentration in a water source. Frequently there is a stoichiometric relationship between the required coagulant dosage and the TOC of the water to be treated. Other important factors include pH and the concentration of divalent cations. Ozone may benefit or retard coagulation, depending on coagulant type and the water quality characteristic that is dominant in setting the optimum coagulant dose.

Enrichment of chalcophile elements in seawater accompanying the end-Cretaceous impact event

2020 ◽  
Vol 132 (9-10) ◽  
pp. 2055-2066
Author(s):  
Teruyuki Maruoka ◽  
Yoshiro Nishio ◽  
Tetsu Kogiso ◽  
Katsuhiko Suzuki ◽  
Takahito Osawa ◽  
...  
Keyword(s):  
Organic Matter ◽  
Iron Oxides ◽  
Sedimentary Rocks ◽  
Reductive Dissolution ◽  
X Ray ◽  
Asteroid Impact ◽  
Chalcophile Elements ◽  
The Difference ◽  
Impact Heating ◽  
Fe Ions

Abstract Chalcophile elements are enriched in the Cretaceous–Paleogene (KPg) boundary clays from Stevns Klint, Denmark. As the concentrations of Cu, Ag, and Pb among several chalcophile elements such as Cu, Zn, Ga, As, Ag, and Pb are correlated with those of Ir, we suggest that these elements were supplied to the oceans by processes related to the end-Cretaceous asteroid impact. Synchrotron X-ray fluorescence images revealed that Cu and Ag exist as trace elements in pyrite grains or as 1–10-µm-sized discrete phases specifically enriched in Cu or Ag. The difference in carrier phases might depend on the materials that transported these elements to the seafloor. Based on their affinities with Cu, Ag, and Ir, iron oxides/hydroxides and organic matter were identified as the potential carrier phases that supplied these elements to the seafloor. Chalcophile elements adsorbed on iron oxides/hydroxides might have been released during reductive dissolution of iron oxides/hydroxides and incorporated into the pyrite produced simultaneously with the reductive dissolution of iron oxides/hydroxides. Both iron oxides/hydroxides and chalcophile elements were possibly released from the KPg target rocks (i.e., sedimentary rocks and/or basement crystalline rocks) by impact heating. Elements with a high affinity to organic matter would have been released upon its degradation and then converted into discrete minerals because of the deficiency in Fe ions. As such discrete minerals include the elements that form acid soluble sulfides such as Cu, Ag, and Pb, enrichment of these elements might have been induced by the intense acid rain just after the end-Cretaceous asteroid impact.

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