Ultraviolet Absorbance Values Research Articles

Olive Oil Quality of Cultivars Cultivated in Super-High-Density Orchard under Cold Weather Conditions

In this work, the quality parameters of the oils of seven different varieties of olives (Olea europaea cvs, “Arbequina”, “Arbosana”, “Cobrançosa”, “Cornicabra”, “Koroneiki”, “Cacereña”, and “Chiquitita”) grown in hedgerow under cold conditions during three consecutive seasons were analyzed in order to evaluate their adaptation to this growing system. For this purpose, virgin olive oils (VOOs) were extracted, and, in addition to evaluating the indices of hydrolytic, oxidative, and sensory deterioration of the oils, their content in photosynthetic pigments and their composition in fatty acids and phenolic compounds were determined. The correlation between oxidative stability and the parameters evaluated has been studied, with the highest correlation coefficients found for the ratio MUFA/PUFA (0.871) and the content of secoiridoid phenolic compounds (0.816). Furthermore, principal component analysis was performed with the phenolic composition data from each season, which demonstrated the major influence of genetic factors in the phenolic composition of VOO. None of the VOOs presented hydrolytic, oxidative, or sensory deterioration, so all of them remained in the “extra” category. However, it should be noted that the mean ultraviolet absorbance values were significantly higher in “Cornicabra” and significantly lower in “Cacereña” oils. In spite of this, the oxidative stability was significantly higher in “Cornicabra” oils (125 h), which also had the highest mean phenolic content (1035 mg kg−1 oil), while the lowest phenolic content values were found in “Arbequina” and “Chiquitita” (58 and 52 h, respectively).

Spectroscopic and Microscopic Analysis of Humic Acid Isolated from Stabilized Leachate HSs Fractionation

Refractory humic substances (HSs), which include humic and fulvic acid as well as hydrophilic portion, are the prime pollutants of stabilized landfill leachate with a concentrated color and chemical oxygen demand (COD). Spectroscopic and microscopic analysis of humic acid remaining in stabilized leachate as a pollutant contributor were conducted in this study. Microfiltration and centrifugation processes were applied to fractionate the humic acid from the HSs of stabilized leachate. The three-stage isolation process recovered a maximum of 1412 ± 2.5 mg/L (Pulau Burung leachate), 1510 ± 1.5 mg/L (Alor Pongsu leachate) at pH 1.5 and 1371 ± 2.5 mg/L (PBLS), and 1451 ± 1.5 mg/L (APLS) of humic acid (about 42% of the total COD concentration) at pH 2.5, which eventually indicates the efficiency of the process. The spectroscopic analysis of isolated humic acid through scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FTIR) significantly indicates the existence of identical elements in the recovered humic acid. The subsequent reduction (around 37%, 36%, and 39%) in ultra-violet absorbance values (UV254, UV280), COD, and color in the humic acid isolated leachate indicates the acid’s significant contribution as a toxic pollutant through aromaticity and conjugated double-bond compounds.

Seasonal variations of natural organic matter (NOM) in surface water supplied to two coal-fired power stations.

Global issues such as pollution and global warming have resulted in changes in water characteristics over the past 20years. Natural organic matter (NOM) which is a major component in water systems has shown an increase globally. This increase in NOM concentration has negatively affected both water treatment processes and drinking water quality. It is subsequently critical to understand the seasonal variations and composition of NOM to be able to address issues related to NOM. In this study, techniques such as ultraviolet-visible spectroscopy, total organic carbon and liquid chromatography-organic carbon detection (LC-OCD) were used for characterisation and quantification of NOM. Two coal-fired power stations were selected for this study with each power station receiving water from a different source, i.e. power station A receives water from the Vaal River and power station B from the Nkomati River. Results from this study demonstrated that composition and concentration of NOM from these two water sources varied seasonally. Characterisation of NOM using the LC-OCD indicated that the different fractions of NOM, i.e. low molecular weight neutrals, low molecular weight acids, building blocks, humic substances and biopolymers, varied seasonally. The dissolved organic carbon concentration and specific ultraviolet absorbance values of the raw water at both power stations showed an increment amid the wet seasons and a decrease amid the dry seasons.

Temperature effects on sorption of dissolved organic matter on ferrihydrite under dynamic flow and batch conditions

AbstractAccurately predicting the effect of temperature on soil C storage remains a crucial objective in the effort to understand, mitigate, and adapt to climate change. Associations between soil organic C and short‐range order minerals like the iron hydroxide ferrihydrite contribute substantially to C sequestration, but little is known about how these associations respond to changes in temperature. We investigated the effects of temperature (7, 25, and 45 °C) and dissolved organic matter (DOM) source and fraction on DOM sorption to ferrihydrite‐coated sand in continuous flow and batch systems at circumneutral pH. Our findings demonstrate a positive relationship between temperature and adsorption, especially between 25 and 45 °C. For aquatic DOM, desorption also increased appreciably with temperature, whereas desorption of peat and soil DOM was less sensitive. More aquatic DOM adsorbed compared with soil DOM at all temperatures, but flow studies revealed that aquatic DOM also desorbed at higher rates. Modeling of DOM breakthrough curves using the advection‐diffusion equation with a modified Freundlich isotherm suggested the partition coefficient increased over time. Specific ultraviolet absorbance values of initial column effluents were low, suggesting that aromatic‐rich compounds preferentially adsorbed to the mineral surface. Our results indicate that some circumstances may favor the accumulation of DOM on iron mineral surfaces as temperature increases, potentially removing organic substrates from the accessible dissolved C pool. However, the stability of new associations likely depends on the chemical characteristics of DOM and the conditions under which it adsorbed.

Antioxidants and cactus extract enhances the sun protection factor of octocrylene and oxybenzone solution

Ultraviolet (UV) filters such as octocrylene and oxybenzone in topical photoprotection products work effectively in absorbing UV radiation, thus minimizing sun damage to the skin. Antioxidants are incorporated into sunscreen products to enhance the photoprotection ability of the products. However, the effectiveness of the antioxidants on the sun protection factor (SPF) of UV filters is not well established. Hence in this study, the effect of caffeine, nicotinamide, β-carotene, α-tocopherol, and cactus extract on the SPF of octocrylene and oxybenzone were investigated. The UV absorbance of octocrylene (5 µg/mL) and oxybenzone (20 µg/mL) in 95% ethanol, with different concentrations of the antioxidants (0.1–100 µg/mL) and cactus extract were measured from 290-320nm. The UV absorbance values were converted to SPF values by the Mansur equation. Statistical analysis was performed by ANOVA test and Post Hoc test (Dundett T3 test) with a significance level of p<0.05 using SPSS software. The antioxidants and cactus extract were found to significantly increase the SPF of octocrylene and oxybenzone solutions in a concentration-dependent manner. Out of the antioxidants tested, β-carotene and α-tocopherol were the most effective antioxidants to increase the SPF of octocrylene solution and oxybenzone solutions, respectively. The results supported that it is beneficial to incorporate antioxidants and cactus extract into the formulation of topical photoprotection products.

Evaluation of disinfection by-product formation during chlor(am)ination from algal organic matter after UV irradiation.

This study evaluated the effect of low-pressure ultraviolet (UV) irradiation on the formation of disinfection by-products (DBPs) from algal organic matter of Microcystis aeruginosa during subsequent chlorination and chloramination. The algal organic matter includes extracellular organic matter (EOM) and intracellular organic matter (IOM). The fluorescence excitation-emission matrix spectra indicated that the humic/fulvic acid-like organics of EOM and the protein-like organics of IOM may be preferentially degraded by UV treatment. UV irradiation with low specific UV absorbance values was effective in reducing the formation of trihalomethanes and dichloroacetic acid from EOM and IOM during the subsequent chlorination. During the UV-chloramine process, higher UV dose (1000mJ/cm2) led to the decrease of the formation of dichloroacetic acid, trichloroacetic acid, and haloketones from IOM by an average of 24%. Furthermore, UV irradiation can slightly increase the bromine substitution factors (BSFs) of haloacetic acids from EOM during chlorination, including dihaloacetic acids and trihaloacetic acids in the presence of bromide (50μg/L). However, UV irradiation did not shift the formation of DBPs from IOM to more brominated species, since the BSFs of trihalomethanes, dihaloacetic acids, trihaloacetic acids, and dihaloacetonitriles almost kept unchanged during UV-chlorine process. As for UV-chloramine process, UV irradiation decreased the BSFs of trihalomethanes, while increased the BSFs of dihaloacetic acid for both EOM and IOM. Overall, the UV pretreatment process is a potential technology in treating algae-rich water.

Spectrophotometry of Artemisia tridentata to Quantitatively Determine Subspecies

Ecological restoration is predicated on our abilities to discern plant taxa. Taxonomic identification is a first step in ensuring that plants are appropriately adapted to the site. An example of the need to identify taxonomic differences comes from big sagebrush (Artemisia tridentata). This species is composed of three predominant subspecies occupying distinct environmental niches, but overlap and hybridization are common in ecotones. Restoration of A. tridentata largely occurs using wildland collected seed, but there is uncertainty in the identification of subspecies or mix of subspecies from seed collections. Laboratory techniques that can determine subspecies composition would be desirable to ensure that subspecies match the restoration site environment. In this study, we use spectrophotometry to quantify chemical differences in the water-soluble compound, coumarin. Ultraviolet (UV) absorbance of A. tridentata subsp. vaseyana showed distinct differences among A.t. tridentata and wyomingensis. No UV absorbance differences were detected between A.t. tridentata and wyomingensis. Analyses of samples from > 600 plants growing in two common gardens showed that UV absorbance was unaffected by environment. Moreover, plant tissues (leaves and seed chaff) explained only a small amount of the variance. UV fluorescence of water-eluted plant tissue has been used for many years to indicate A.t. vaseyana; however, interpretation has been subjective. Use of spectrophotometry to acquire UV absorbance provides empirical results that can be used in seed testing laboratories using the seed chaff present with the seed to certify A. tridentata subspecies composition. On the basis of our methods, UV absorbance values < 2.7 would indicate A.t. vaseyana and values > 3.1 would indicate either A.t. tridentata or wyomingensis. UV absorbance values between 2.7 and 3.1 would indicate a mixture of A.t. vaseyana and the other two subspecies.

Microwave Heating of Different Commercial Tunisian Olive Oil: Regarding to Exposure Times on Physical and Chemical Parameters Properties

In this work the effect of different microwave heating times, that simulate the usual times used to cooking, on Tunisian olive oils was investigated. Traditional parameters, including free acidity, peroxide value, ultraviolet absorbance values at 232 and 270 nm, phenolic, chlorophyll and carotenoid compositions, were determined in four extra-virgin olive oil samples before and after microwave treatment. The results showed that heating by microwave apparatus produce losses in the quality of the different analyzed olive oils. The heating time did not promote the occurrence of hydrolysis in the samples since no changes in free acidity values were found. All other parameters were affected by exposure time in a similar way: in the first 3 min no marked changes were observed, after that the quality of the oil decrease significantly. Globally, the microwave heating time also affects the total chlorophylls, carotenoids and phenolic contents which clearly decreased as long as the exposure time increases. The use of extra-virgin olive oil may be encouraged especially at short microwave treatment times for both domestic and food catering applications.

Effect of pre-ozonation on the formation and speciation of DBPs

The objective of this study was to quantitatively evaluate the effect of pre-ozonation on the formation and speciation of disinfection byproducts (DBPs) from subsequent chlorination and chloramination. Laboratory experiments were conducted on six diverse natural waters with low to medium bromide concentrations. Four groups of DBPs were investigated in this study: trihalomethanes (THMs), trihaloacetic acids (THAAs), dihaloacetic acids (DHAAs), and dihaloacetonitriles (DHANs). The results showed that the relative destructions of chlorination DBP precursors by ozone generally follow the order of DHANs > THMs & THAAs > DHAAs. Pre-ozonation substantially increased the DHAA precursors in the waters with low specific ultraviolet absorbance values. Pre-ozonation shifted the formation of DBPs to more brominated species. The bromine substitution factors (BSF) of different chlorination DBPs typically increased by 1–8 percentage points after ozonation. Pre-ozonation reduced the yields of chloramination DHAAs and THMs and increased the BSFs of chloramination DHAAs by 1–6 percentage points.

Preparation and use of magnetic poly(glycidyl methacrylate) resin in drinking water treatment

AbstractMagnetic poly(glycidyl methacrylate) (m‐PGMA) was synthesized and characterized, and its efficiency in removing natural organic matter (NOM) and carbamazepine (CBZ) from synthetic water was studied. The effects of factors such as time and m‐PGMA dosage on NOM removal were investigated. Furthermore, magnetic ion exchange resin (MIEX®) was used for comparison with m‐PGMA in CBZ removal. m‐PGMA was found to have a strong magnetic character whose specific saturation magnetization and mass fraction of magnetite were 10.79 emu g−1 and 6.166 wt %, respectively, thus providing additional utility for m‐PGMA in slurry form in completely mixed continuous‐flow reactors. Lab‐scale studies showed that the removal rate rose rapidly with time and reached a pseudo‐equilibrium after 30 min. In addition, the highest doses of m‐PGMA achieved the highest removal efficiency. After 30 min of contact with 5, 10, and 15 mL L−1 of m‐PGMA, the removal rates, based on UV absorbance measurements at 254 nm (UV254), were 56%, 67%, and 79%, respectively, whereas the removal rates of dissolved organic carbon (DOC) were 53%, 60%, and 72%, respectively. Additionally, the scale ultraviolet absorbance values (SUVA) decreased during a 30 min contact time, thereby suggesting that the NOM removed by m‐PGMA had greater aromatic character. In multiple‐loading tests, UV254 removal gradually decreased and achieved 18.39% at 1600 bed volume; it was kept constant at this level. Compared to MIEX®, m‐PGMA had a higher CBZ removal rate (27.8% and 34.7% for 20 mL L−1 and 25 mL L−1 of m‐PGMA, corresponding to the removal of 200 μg L−1 CBZ). The resulting higher removal rate of CBZ contributed to stronger adsorption, a higher specific surface area, and larger pore volume. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

The response of typical South African raw waters to enhanced coagulation

Drinking water treatment plants in South Africa rely almost entirely on surface water sources, which are often compromised due to high return flows and indirect reuse. The typical treatment plants focus on the removal of physical and microbial contaminants which include turbidity, colour, chemical compounds and microorganisms. A relatively new concern to this list is natural organic matter (NOM) which has become a major concern in potable water treatment due to its recent regulation. In this study, eight different raw water samples from the various water types found in the country were seasonally collected and treated for the removal UV absorbance at a wavelength of 254 nm (UV254) using enhanced coagulation (EC). The efficacy of EC, which can be employed as a practical technology in the removal of both turbidity and NOM, was evaluated in remaining UV254 from these raw water sources. Jar tests were conducted, with ferric chloride used as the coagulant (due to its extensive use as a coagulant in the water treatment industry in South Africa) and specific pH values (initial water pH, 7.0, 6.0, 5.5, 5.0 and 4.5) were chosen as target values guiding the six different coagulant dosages for the jar tests. The pH of the low-alkalinity (&amp;lt;60 mg/L CaCO3) raw waters were adjusted and raised by the addition of sodium carbonate. The response parameters of the tests were turbidity (NTU), pH and UV254. Algorithms for finding the optimum coagulant dosage for UV254 removal were developed and consistently applied to all the results. Results showed large variations in the nature of NOM across the country from specific ultraviolet absorbance values. From the UV254 values, the concentrations of NOM also varied greatly geographically than temporally. The general trend observed in the EC results suggested that the pH should always be dropped to between 4.5 and 7.0 to lower the amounts of UV254 and turbidity to reasonable levels.

Characteristics of natural organic matter and formation of chlorination by-products at Masaka waterworks

Research Article| December 01 2011 Characteristics of natural organic matter and formation of chlorination by-products at Masaka waterworks H. M. Kalibbala; H. M. Kalibbala 1Department of Civil & Environmental Engineering, College of Engineering, Design, Art & Technology, Makerere University, P.O. Box 7062, Kampala, Uganda E-mail: hkalibbala@tech.mak.ac.ug Search for other works by this author on: This Site PubMed Google Scholar Rose Kaggwa; Rose Kaggwa 2External Services, National Water & Sewerage Corporation, P.O. Box 7053, Kampala, Uganda Search for other works by this author on: This Site PubMed Google Scholar O. Wahlberg; O. Wahlberg 3Department of Inorganic Chemistry, Royal Institute of Technology (KTH), Teknikringen 30, SE-100 44 Stockholm, Sweden Search for other works by this author on: This Site PubMed Google Scholar E. Plaza E. Plaza 4Department of Land & Water Resources Engineering, Royal Institute of Technology (KTH), Teknikringen 30, SE-100 44 Stockholm, Sweden Search for other works by this author on: This Site PubMed Google Scholar Journal of Water Supply: Research and Technology-Aqua (2011) 60 (8): 511–519. https://doi.org/10.2166/aqua.2011.076 Article history Received: November 01 2010 Accepted: September 28 2011 Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Cite Icon Cite Permissions Search Site Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAll JournalsThis Journal Search Advanced Search Citation H. M. Kalibbala, Rose Kaggwa, O. Wahlberg, E. Plaza; Characteristics of natural organic matter and formation of chlorination by-products at Masaka waterworks. Journal of Water Supply: Research and Technology-Aqua 1 December 2011; 60 (8): 511–519. doi: https://doi.org/10.2166/aqua.2011.076 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex To minimise the formation of chlorination by-products (CBPs) it is imperative that attention is directed towards the structure and occurrence of natural organic matter (NOM) in raw water sources, and its flow and fate during water treatment processes. In this study, an assessment of the characteristics and flow of NOM along the treatment train at the full scale treatment plant at Masaka, Uganda, was made. Results indicated that 79% of the NOM, determined as total organic carbon, was in the dissolved form (DOC) with 83% of the DOC being hydrophilic in character. The insignificant amount of hydrophobic fraction in the raw water implies that the contributing fraction to THMs formation was mainly the hydrophilic component which subsequently was poorly removed along all units except clarification. The treated water from all unit processes provided specific ultraviolet absorbance values greater than 2 L/mg-m at 254 nm wavelength, indicating that it still had a high potential of reacting with chlorine to form CBPs. This renders water from Nabajjuzi River as unsuitable for chlorination in early stages of treatment and necessitating modification of the processes to reduce or avoid formation of unwanted by-products. chlorination by-products, drinking water, natural organic matter This content is only available as a PDF. © IWA Publishing 2011 You do not currently have access to this content.

Influence of Particle Size on the Ultraviolet Spectrum of Particulate-Containing Solutions: Implications for In-Situ Concentration Monitoring Using UV/Vis Fiber-Optic Probes

To critically evaluate the effect of submicron and micron-sized organic particulates on the ultraviolet (UV) absorption spectra of aqueous systems and assess the applicability of UV/Vis fiber-optic probes for in-situ concentration monitoring in the presence of particles of different sizes. UV absorbance spectra were obtained for aqueous felodipine suspensions containing a range of particle sizes (300 nm-400 μm) and suspension concentrations and for methanolic solutions of different concentrations and amorphous films of different thicknesses. Select suspensions were further characterized using nuclear magnetic resonance (NMR) experiments. Mie theory was used to provide insight into the role of particle size on scattering and absorption of UV radiation. Large increases in absorbance as a function of total suspension concentration were observed for nanosuspensions but not for the other particle sizes evaluated. NMR measurements of solution concentration indicated that the observed increases in UV absorbance values for these systems were not caused by increases in the concentration of dissolved molecules, implying that nanoparticles of felodipine might absorb UV light. Mie theory-based calculations enabled reconstruction of the experimental observations and supported this hypothesis. For solutions containing small (submicron) felodipine particles, UV spectra were influenced by absorption of the particles and contributions from absorption of dissolved molecules and scattering of the particles. Caution should be applied when using in situ UV/VIS-probes to monitor the amount of dissolved material during dissolution, in particular when small particles are present (e.g. dissolution of nanoparticulate formulations) or generated (e.g. precipitation of supersaturated solutions) in the dissolution medium.

On the quality control of ‘olive paste’, a specialty based on olives and olive oil

Abstract‘Olive paste’ is a preserved food gaining popularity as a gourmet product. Its quality depends on that of the major ingredients, table olives (green or black) and virgin olive oil, as well as on the changes occurring to the constituents of the latter during preparation and storage. In this view, our attention was focused on the characteristics of the lipid fraction (l.f.) of a great number of commercial products after a careful search in retail markets and the web. Ultraviolet absorbance values (K232, K270) of the l.f., a criterion set for edible and non‐edible olive oil oxidative status due to paste heat treatment during pasteurization, could not support the label information regarding the quality of the oil used. On the contrary, the content of α‐tocopherol (˜250 mg/kg l.f. or ˜50 mg/kg paste) was a strong indication of good‐quality major ingredients. Within each brand, consistency with labeling was checked through squalene (higher content in products containing higher amounts of olive oil) or β‐carotene determination (higher levels in preparations containing red pepper). For green olive paste samples, the values of the ratio pheophytin a/pyropheophytin a may be used to monitor the shelf life of the product. The findings support routine quality control of the new product.

Effect of bromide ion on isolated fractions of dissolved organic matter in secondary effluent during chlorination

The role of bromide ion in the trihalomethane (THM) formation and structure of dissolved organic matter (DOM) during chlorination of the secondary effluent taken from the Wenchang Wastewater Treatment Plant (Harbin, China) was investigated. DOM was fractionated using XAD resins into five fractions: hydrophobic acid (HPO-A), hydrophobic neutral (HPO-N), transphilic acid (TPI-A), transphilic neutral (TPI-N) and hydrophilic fraction (HPI). The patterns of individual THM species with increased bromide concentrations were similar for all DOM fractions. The THM speciation as well as halogen fraction for these five fractions followed similar trends with the Br −/Cl 2 ratio. Chlorination resulted in decreased ultraviolet (UV) absorbance across wavelengths from 250 to 280 nm for DOM fractions whether bromide ions existed or not, and bromide addition led to lower differential UV absorbance values. Fourier-transform infrared (FT-IR) results indicated that chlorination, whether bromide ions existed or not, resulted in the near elimination of aromatic C H and amide peaks, increased C O absorption intensity and occurrence of C O and C Cl peaks for HPO-A, HPO-N, TPI-A and TPI-N. Furthermore, bromide addition in chlorination led to the occurrence of C Br peak for all four fractions.

Feasibility of On-line Measurement of Sewage Components Using the UV Absorbance and the Neural Network

The objective of this study was to test the feasibility of a new method to improve the accuracy in the estimation of sewage components. Adding to the regression of sewage components with UV (ultraviolet) absorbance values, a proposed method considered an unclear but existing relationship among characteristic of sewage production. Sewage production showed very defined profiles due to the daily human activities. So the main idea was the combination of measuring the UV absorbance values and analyzing the characteristics of the sewage production. For this purpose, 446 sewage samples taken at every 2-h interval for 51 days at a wastewater treatment plant were statistically analyzed using neural network (NN). NN was trained with 350 data sets (about 29 days) of UV absorbance values, flow rate and time. And as a result, it could predict 96 data (12 days) as a validation, indicating that estimation accuracies were improved to higher level than those of the linear regressions. The proposed method could estimate concentrations of total nitrogen (TN) and total phosphate (TP) within practical accuracies as well as total suspended solid.

UV Inactivation of Bacteria in Raw and Pre-Treated Liquid Swine Manure

The study was conducted to investigate the effectiveness of ultraviolet (UV) irradiation for inactivating coliform bacterial indicators in liquid swine manure samples using a laboratory-scale, low-pressure UV collimated beam apparatus. Raw liquid swine manure was brought from the field and stored at 4 °C for preliminary settling for 24 hours, which was followed by alum treatment in a jar test apparatus. Both pre-settled and alum-treated supernatants were filtered separately through different pore-sized polycarbonate membrane filters. The unfiltered and filtered pre-settled and alum-treated supernatant samples were exposed to a range of UV fluences (i.e., doses) to determine the fluence-response relationship. After preliminary settling, alum treatment, and membrane filtration, UV absorbance values of undiluted swine manure samples at 254 nm varied between 4.0 and 4.2 cm−1 with total suspended solids concentrations of 800 to 1,800 mg 1−1. Total coliforms were reduced by 2 - to 2.5-log10 at UV fluences of 80 to 100 mJ cm&minus2. Relatively small log reductions (< 0.5-log10) were observed at lower fluences (below 20 mJ cm−2) in undiluted manure samples. To reduce the UV absorbance of liquid swine manure, raw manure was diluted 1:50 and 1:10 with deionized water in subsequent experiments. Almost complete inactivation (> 4 to 5 log10) was achieved at UV fluences of 20 mJ cm−2 or higher in the swine manure samples diluted to 1:50. Based on these findings, it was proposed that UV inactivation of coliform in the undiluted liquid swine manure was limited by association of bacterial cells with particulate matter of less than 10 μm in size. Dilution may have disrupted and reduced the association between the bacteria and this fine particulate matter resulting in better dispersion and more complete inactivation by UV.

Characteristics and Reactivity of Algae-Produced Dissolved Organic Carbon

Algae (green, blue–green, and diatom) grown in inorganic media produced particulate and dissolved organic carbon (DOC). DOC produced by a green-alga contains 25% hydrophobic acids. DOC from all algae had specific ultraviolet absorbance values less than 2.0 m−1 (mg∕L)−1 . Algae-produced DOC was biologically labile; greater than 60% degraded in bioreactors within 5 days. The biodegradable material likely included carbohydrates, amino acids, and amino sugars, which were present in hydrophobic acid isolates. Chlorination of algal DOC formed disinfection by-products; DOC from the green alga, Scenedesmus quadricauda, produced chloroform [0.53 micromole per mg carbon (μmol∕mg C)] , dichloroacetic acid (0.27 μmol∕mg C) , and trichloroacetic acid (0.14 μmol∕mg C) . This work complements other studies, which focused on algal total organic carbon (DOC and cellular material), and clearly demonstrates the importance of identifying algae-derived sources of DOC in water supplies and removing such DOC in water treatment ...

Factors influencing the formation and relative distribution of haloacetic acids and trihalomethanes in drinking water.

Various water quality and treatment characteristics were evaluated under controlled chlorination conditions to determine their influences on the formation and distribution of nine haloacetic acids and four trihalomethanes in drinking water. Raw waters were sampled from five water utilities and were coagulated with alum and fractionated with XAD-8 resin. The resulting four fractions--raw and coagulated water and the hydrophobic and hydrophilic extracts--were then chlorinated at pH 6 and 8 and held at 20 degrees C for various contact times. The results show that increasing pH from 6 to 8 increased trihalomethane formation but decreased trihaloacetic acid formation, with little effect on dihaloacetic acid formation. More trihalomethanes were formed than haloacetic acids at pH 8, while the reverse was true at pH 6. Hydrophobic fractions always gave higher haloacetic acid and trihalomethane formation potentials than their corresponding hydrophilic fractions, but hydrophilic carbon also played an important role in disinfection byproduct formation for waters with low humic content. The bromine-containing species comprised a higher molar proportion of the trihalomethanes than of the haloacetic acids. The hydrophilic fractions were more reactive with bromine than their corresponding hydrophobic fractions. Coagulation generally removed more haloacetic acid precursors than trihalomethane precursors. Waters with higher specific ultraviolet absorbance values were more amenable to removal of organic material by coagulation than waters with low specific ultraviolet absorbance values. Experimental evidence suggests that haloacetic acid precursors have a higher aromatic content than trihalomethane precursors.

Enhanced coagulation using a magnetic ion exchange resin

The objective of this investigation was to examine the effectiveness of a magnetic ion exchange resin (MIEX ®) to enhance the coagulation of disinfection by-product precursors in nine surface waters, each representing a different element of the USEPA's 3×3 enhanced coagulation matrix. The effect of MIEX-pretreatment on the requisite alum dose needed for subsequent coagulation of turbidity was also evaluated. Enhanced coagulation with MIEX was found to be very effective for removing trihalomethane (THM) and haloacetic acid (HAA) precursors from the nine waters examined. THM and HAA formation potential was reduced by more than 60% in all of the waters studied; reductions approaching 90% were seen in the waters with the highest specific ultraviolet absorbance values. The residual total organic carbon concentration, ultraviolet absorbance, and THM and HAA formation potential were all substantially lower as a result of MIEX and alum treatment compared to alum coagulation alone. MIEX pre-treatment also lowered the coagulant demand of each of the waters substantially.