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PubMed2006

Electrolytic degradation of biorefractory organics and ammonia in leachate from bioreactor landfill.

Electrochemical oxidation was applied to treat the effluent from bioreactor landfill with leachate recirculation, characterised as poor biodegradability and high NH3-N concentration. In this study, the effluent was electrolysed in a batch reactor with Ti/TiO2-IrO2-RuO2 anode and stainless steel cathode. The oxidation of dissolved organic matter (DOM) during electrolysis was evaluated based on the evolution of molecular weight grade, hydrophilic fractionation (humic acid, fulvic acid and hydrophilic fractions), specific ultraviolet absorbance (SUVA254) and AOX. The impact of the initial NH3-N concentration on the oxidation was discussed. The results showed that at a current density of 100 mA/cm2, electrolysis time of 1.5 h and electrode gap of 1 cm, NH3-N with an initial concentration of 1.2 g/L could be completely eliminated and 56% of COD with an initial concentration of 1.2 g/L could be removed, which illustrated that the electrolysis-produced chlorine preferentially oxidised ammonia. The electrolysis mainly resulted in the degradation of humic substances and other high molecular DOM, followed by the increase of BOD/COD ratio and decline of SUVA254 of the leachate. The current efficiencies for COD and ammonia oxidation gradually decreased during the electrolysis, with the latter obviously higher than the former. At the optimal electrolysis time of 1.5 h, NH3-N could be totally removed and the BOD/COD ratio could be enhanced to 0.3, which was also favourable to control the AOX at a reasonable level.

Ammonia↗

PubMed1996

Modeling ruminant feed intake with protein, chemostatic, and distention feedbacks.

Little progress has been made in modeling intake regulation in spite of the many mechanisms identified as important. A model with relatively simple inputs was developed that included compartments for protein, soluble carbohydrate, digestible fiber, and very slowly digesting fiber. Distention and chemostatic feedbacks were combined using a previously published equation. The ratio of current ruminal fill to a modulating parameter for ruminal fill represented distention feedback. The ratio of the current flow of available energy to a modulating parameter for chemostatic demand represented chemostatic feedback. The modulating parameter for ruminal fill was based on literature reports of ruminal contents. Intake was adjusted based on current fill and energy flow relative to modulating parameters for fill and chemostatic feedback. The effect of the digestible organic matter (DOM) to CP ratio on DOM intake was modeled to adjust rates of digestion, rates of passage, and the chemostatic feedback. The model tested an integrated concept of intake regulation with only CP, IVDMD, and NDF as inputs. In spite of relatively simple inputs, the model behavior in response to variation in protein, digestibility, and fiber was similar to observations of animal responses.

Animals↗

PubMed1998

Behavioral, endocrine, immune, and performance measures for pigs exposed to acute stress.

Weanling pigs (n = 132) were used to investigate the effects of three common stressors (and a control) and differing social status on behavior, immunity, plasma cortisol, blood chemical, and performance measures. Eleven blocks of 12 pigs each were evaluated. Each pen contained three pigs of dominant (DOM), intermediate (INT), or submissive (SUB) social status. Two weeks later, random pens of pigs experienced either a control treatment (CON) or they were stressed for 4 h by shipping (SHIP), heat-stressed (HEAT) with overhead heat lamps in their home pens, or cold-stressed (COLD) by direct application of water and an air current. Treatments did not influence body weights; however, percentage weight loss during SHIP was greater than for other treatments. Body weights were heavier for DOM pigs than for INT and SUB pigs. Social status had large effects on plasma cortisol, globulin, acute-phase proteins, body weight, and weight changes. Only acute shipping stress resulted in weight loss. Many immune and blood measures were not changed among acutely stressed pigs; however, the relationship between social status and mitogen-induced lymphocyte proliferation and natural killer cell cytotoxicity was disrupted during acute stress. Pig behavior was significantly changed by each stress treatment in a unique manner. During acute stress, behavioral changes seem to be the most consistent and reliable indicators.

Animals↗

PubMed2001

Performance of light vs heavy steers grazing Plains Old World bluestem at three stocking rates.

Live weight gains of light and heavy calves grazing Plains Old World bluestem at three stocking rates were evaluated during the summers of 1997 and 1998. Initial weights of mixed-breed light-weight steers (LHT) were 141 SD = 17 kg (n = 214) in 1997 and 160 SD = 23 kg (n = 193) in 1998. Initial weights of mixed-breed heavy steers (HWT) were 265 SD = 17 kg (n = 115) in 1997 and 248 SD = 13 kg (n = 126) in 1998. Initial stocking rates for both sizes of steers were as follows: light, 392 kg of live weight/ha; moderate, 504 kg of live weight/ha (increased to 616 kg live weight/ha in 1998); and heavy, 840 kg of live weight/ ha. Averaged gain and gain/hectare are reported as stocking rate by steer type within year. Heavy steers had greater ADG than LHT steers during both years. Forage intake, expressed as a percentage of BW, was greater (P = 0.05) for LHT (3.1%) than for HWT (2.8%) calves. Grazing time (min/d; 1998 only) was greater (P = 0.05) for LHT (665) than for HWT (624) steers. Forage CP and in vivo digestible organic matter (DOM) were slightly greater (P < 0.05) in pastures grazed by HWT vs LHT cattle. Gain/hectare was greater (P < 0.05) for LHT than for HWT calves at all three stocking rates during both years. A linear decline in ADG was observed (P < 0.07) as stocking rates increased for HWT steers in 1997 and LHT steers in 1998. However, ADG did not decline with increasing stocking rate for LHT calves during 1997 or HWT calves during 1998. Forage intake was not different among stocking rates in either 1997 or 1998. Grazing time was greatest (P < 0.05) for steers in the moderate and heavy stocking rates. Forage in vivo DOM decreased (P < 0.05) as stocking rate increased. Both LHT and HWT steers had lower (P < 0.05) ADG at all three stocking rates during 1998 compared with 1997. Despite lower ADG, LHT steers had greater gain/hectare than HWT steers during both 1997 and 1998.

Animal Husbandry↗

PubMed1983

Production of fine-wool ewes on yearlong rangeland in West Texas. I. Effects of season, stage of production and supplemental feed on intake.

Effects of season, reproductive stage and supplemental feed on fecal output, forage intake and digestible organic matter intake (DOMI) were determined in fine-wool ewes on rangeland. Fecal output was highest during winter and was not affected by supplemental feed level. Forage intake was similar across seasons, but DOMI was higher during spring because of the higher digestible organic matter (DOM) concentration in the diet. Lactating ewes consumed 35 to 40% more forage and DOM compared with nonlactating ewes. Nonlactating nonpregnant and pregnant ewes had similar intakes. Forage intake and DOMI during summer were intermediate to those observed during winter and spring. Supplemental feed tended to decrease forage intake and slightly increase DOMI, suggesting a substitution effect. It is suggested that intake was limited during winter by maximum passage of undigested residues. Other mechanisms are proposed for limiting intake during spring and summer. Comparison of intake data with National Research Council standards indicates that energy intake was low during most of the year under the conditions of this study.

Animal Feed↗

PubMed1995

Assessment of the discriminative stimulus effects of the optical isomers of ecstasy (3,4-methylenedioxymethamphetamine; MDMA).

The discriminative stimulus effects of the stereoisomers of 3,4-methylenedioxymethamphetamine (MDMA) were studied in rats trained to discriminate 1.25mg/kg of (+)-MDMA or 3.5mg/kg of (-)-MDMA from saline, in a two lever, water-reinforced, drug discrimination situation. The isomers of MDMA and 3,4-methylenedioxyamphetamine (MDA) substituted completely for both training drugs. The stimulants amphetamine and cocaine did not substitute for either MDMA isomer. The hallucinogens (+/-)-2,5-dimethoxy-4-methylamphetamine (DOM), (+)-lysergic acid diethylamide (LSD), and mescaline failed to substitute completely for (+)-MDMA. Similarly, DOM and mescaline did not substitute for (-)-MDMA; however, LSD did substitute for this isomer at a dose of 0.06mg/kg but not at higher doses. Substitution tests with 5-HT-releasing agents revealed that fenfluramine substituted partially for (+)-MDMA and completely for (-)-MDMA, while p-chloroamphetamine substituted completely for both isomers of MDMA. When given in combination with (+)-or (-)-MDMA, neither the 5-HT(2) antagonist pirenpirone nor the less selective 5-HT antagonist metergoline consistently blocked drug-appropriate responding. These results indicate that the stereoisomers of MDMA and MDA have similar discriminative stimulus properties. More importantly, the present findings suggest that 5-HT release may be important for the discriminative stimulus effects of (+)-and (-)-MDMA. Actions at 5-HT(2) receptors, however, do not appear to be critical.

Journal Article↗

PubMed2001

A new economical method to remove humic substances in water: adsorption onto a recycled polymeric material with surfactant addition.

Cationic surfactants were used to enhance the adsorption of dissolved organic matter (DOM), contained in the effluent of municipal wastewater, onto polypropylene (PPL), a polymeric synthetic adsorbent made from recycled plastics. Both batch and continuous up-flow column experiments were carried out. The DOM, in the form of humic acid, was treated with a range of cationic surfactants, then, adsorption experiments were conducted to evaluate the adsorption of the mixture onto PPL in both its soluble and precipitated forms. This research validated the feasibility of the proposed system in which anionic humic acid is removed from the aqueous phase by forming neutral hydrophobic molecules with cationic surfactants and subsequently by adsorbing them on the hydrophobic surface of PPL.

Adsorption↗

PubMed2001

Biotic ligand model of the acute toxicity of metals. 1. Technical basis.

The biotic ligand model (BLM) of acute metal toxicity to aquatic organisms is based on the idea that mortality occurs when the metal-biotic ligand complex reaches a critical concentration. For fish, the biotic ligand is either known or suspected to be the sodium or calcium channel proteins in the gill surface that regulate the ionic composition of the blood. For other organisms, it is hypothesized that a biotic ligand exists and that mortality can be modeled in a similar way. The biotic ligand interacts with the metal cations in solution. The amount of metal that binds is determined by a competition for metal ions between the biotic ligand and the other aqueous ligands, particularly dissolved organic matter (DOM), and the competition for the biotic ligand between the toxic metal ion and the other metal cations in solution, for example, calcium. The model is a generalization of the free ion activity model that relates toxicity to the concentration of the divalent metal cation. The difference is the presence of competitive binding at the biotic ligand, which models the protective effects of other metal cations, and the direct influence of pH. The model is implemented using the Windermere humic aqueous model (WHAM) model of metal-DOM complexation. It is applied to copper and silver using gill complexation constants reported by R. Playle and coworkers. Initial application is made to the fathead minnow data set reported by R. Erickson and a water effects ratio data set by J. Diamond. The use of the BLM for determining total maximum daily loadings (TMDLs) and for regional risk assessments is discussed within a probabilistic framework. At first glance, it appears that a large amount of data are required for a successful application. However, the use of lognormal probability distributions reduces the required data to a manageable amount.

Animals↗

PubMed2001

Exposure of cattle immunized with different stocks of Theileria parva to buffalo-associated Theileria challenge on two game parks in Zimbabwe.

Eight cattle immunized with cattle-derived Theileria parva Boleni stabilate together with six susceptible controls were released in Dombawera Game Park on the Highveld of Zimbabwe. This coincided with Rhipicephalus appendiculatus nymphal activity. The cattle grazed together with African buffaloes (Syncerus caffer) and were not treated against tick infestation. The nymphal tick infestation was high, and seven of the eight immunized cattle and three of the controls had severe and fatal reactions. Subsequently, two stocks of Theileria parva to be tested for their immunizing abilities were prepared-one from adult ticks which were fed as nymphs on one of the sick control animals (Dom 268) and the other from adult ticks collected from pastures grazed by buffaloes (Bv-1). Two groups of cattle were immunized with either the Dom 268-derived strain (eight animals) or the Bv-1-derived strain (four animals). These together with three non-immunized controls, were released in Bally Vaughaun Game Park in the Highveld, where buffaloes are present, during the season of nymphal tick activity. A third group of five cattle, immunized with stabilate Bv-1, and three non-immunized controls were released at the same site during the season of adult tick activity. The nymphal and adult tick infestations of the cattle were large and more than 2000 nymphs and 1000 adult ticks were counted per animal. Cattle were treated with a pyrethroid pour-on preparation to control the tick infestation and screw-worm strike. The immunized cattle in the three groups survived the theileriosis challenge for a period of 18 months, but the non-immunized control cattle suffered a severe and fatal theileriosis 19-23 days after being placed on the pasture.

Animals↗

PubMed2001

Fractionation and characterization of sludge bacterial extracellular polymers by FT-IR, 13C-NMR, 1H-NMR.

Sludge bacterial extracellular (BEP) polymers exhibit a strong affinity with metals in addition to their role in the bioflocculation of activated sludge. It is of utmost importance in elucidating the chemical characterization of sludge BEP prior to a better understanding of its environmental behavior. Sludge BEP extracted from activated sludge was characterized by FT-IR, 1H-NMR, and 13C-NMR and fractionated into 6 fractions (hydrophilic acid, base, and neutral; and hydrophobic acid, base, and neutral). The results indicated that sludge BEP contained more polysaccharides but fewer amino acids or proteinaceous materials compared to dissolved organic matter (DOM) derived from sludge. No aromatic substance was found in sludge BEP as indicated by NMR. Sludge BEP was dominated by hydrophilic fractions, accounting for 65% of total DOC of sludge BEP and hydrophilic neutral constituted about 58% of the hydrophilic fraction. The chemical fraction and characterization indicated that sludge BEP might exhibit a higher capability in enhancing the transport of the associated contaminants through porous media than that of sludge DOM.

Bacteria↗

PubMedDate not supplied

Molecular weight of dissolved organic matter-napropamide complex transported through soil columns.

Soil-derived dissolved organic matter (DOM) has been shown to form stable complexes with the herbicide napropamide [2-(alpha-naphthoxy-N,N-diethylpropionamide] capable of enhancing the transport of napropamide through soil columns. Two soils, one containing sewage sludge-derived organic matter (SS) and the other having only natural organic matter (NoSS) were treated with napropamide and allowed to dry to promote complex formation. Soil columns were prepared by packing a 10-cm layer of untreated, dry, sieved soil followed by an overlying 5-cm layer of napropamide-treated soil. Columns were irrigated and the effluent collected and placed in dialysis chambers. After equilibration napropamide concentrations were determined on both sides of the membrane and complex and quantified based on the amount of napropamide unable to cross the membrane. it was found that for the SS soil 7% and for the NoSS 2.4% of the applied napropamide underwent facilitated transport. In addition, most of the complex transported through the columns had a molecular weight between 500 and 1000 Daltons (Da). The solutions from the SS soil were also found to have formed at least two distinct complexes that were resolved after passing through the untreated soil layer. The results obtained were in agreement with other published results and the techniques used offer a way to separate and concentrate DOM complexes from column effluents for further characterization.

Herbicides↗

PubMed2002

[Incidence rate of rheumatic diseases in Russian population: 10-year analysis].

AIM: To analyze trends in rheumatic diseases (RD) incidence rate in population of Russia for a recent decade. MATERIAL AND METHODS: Medical RD statistics for all regions of Russia for 10 years (1990-1999) have been analysed. RESULTS: Annual number of primary patients with RD has increased for 1990-1999 from 9,147,000 to 12,378,000 (by 35.3%). The percentage of patients with acute rheumatic fever and chronic RD of the heart diminished from 6.5 to 2.9%. Most of the diseases constitute the diseases of osteomuscular system and connective tissue (DOMS). The number of new cases with rheumatic heart diseases (RHD) in adolescents and adults has risen by 50 and 40%, respectively. RHD are especially frequent in the Volga-Vyatka and North-Caucasian regions (2.5 and 2.3 per 1000 against mean Russian 1.7). A total DOMS morbidity has increased for the recent decade by 41%. It is higher in the Central and North regions, in the West Siberia and lower in the North Caucasus, Far East, East Siberia. For the 7 years the above morbidity among children rose 2-fold, among adolescents--2.4-fold. Incidence of rheumatoid arthritis and ankylosing spondylarthritis in adult population of Russia has changed insignificantly while osteoarthrosis total and primary occurrence for 6 years increased by 78 and 58%, respectively. CONCLUSION: RD become a real challenge for health service of Russia. Changes in RD structure require correction of the rheumatic service activities.

Adolescent↗

PubMed2002

Trace metal distribution in soluble organic matter from municipal solid waste compost determined by size-exclusion chromatography.

Municipal solid waste (MSW) composts carry high amounts of trace metals and organic complexing agents that may influence metal bioavailability and mobility after application to soils. In order to assess the degree of organic complexation of trace metals in the solution phase of MSW compost and the relevance of organic ligand type, size exclusion chromatography (SEC) was applied to compost-extracted organic ligands. Adjustment of the elution conditions minimized the interaction with the gel matrix for compost humic substances and dissolved organic matter (DOM) fractions. The SEC was then used to separate the aqueous compost extract into samples with distinct differences in chemical constituents. The highest quantities of Cu, Zn, Ni, Mn, and Cd were found to coelute with the main peak of the SEC elution curve, which, as observed by Fourier-transformed infrared (FTIR) spectroscopy, also had the highest density of carboxyl groups. The ratio of aromatic to aliphatic structures was higher for eluates with low retention times, and cations such as Al, Cr, and Fe were preferably associated with these larger organic molecules. All trace metals in the compost solution phase were bound mostly to DOM rather than forming inorganic complexes.

Biological Availability↗

PubMed2002

[Effect on trihalomethane forming for different molecular weight dissolved organic matter in water resource].

A raw water sample was collected from Guangzhou section of Pearl River to support experiment studies. The sample were passed through Amicon YC-05, YM-1, YM-3, YM-10, YM-30, YM-100 and ZM-500 series membranes after being pretreated. The molecular weight distribution of the isolate for each membranes were analyzed, and the isolates were disinfected by chlorine and chlorine dioxide. The results showed that the RO isolate was the main dissolved organic matter (DOM) in the water sample, which proved that the water was highly contaminated by human activities, and it was the main THMs precursor in the disinfection process with chlorine and chlorine dioxide for all the isolates. Meanwhile, the disinfection process for water sample contain DOM that its molecular smaller than 500 were very different from raw water.

Disinfection↗

PubMed2003

The role of organic matter lost in kraft pulping material balances .

Efficiency improvement in a pulp mill includes minimisation of environmental discharges simultaneously with the development of pulp quality and production economy. Material balances in production processes, including fate of sidestreams, are key in proceeding these matters. Different approaches of determining the material balances increase understanding of process behaviour. We have focused on measuring sidestream (carryovers, washing water, filtrate) dissolved organic matter (DOM) in fibreline unit process blocks of softwood ECF bleached kraft production. The DOM was analysed by traditional wastewater methods (volatile solids, organic carbon, chemical oxygen demand). The measured data was combined with primarily simulated water balances and routine operational mill data in a simulation model. From this balance, yield estimate included, lost organic matter through complete degradation (CD) and volatile organic compounds (VOC) can be calculated throughout the fibreline. The sensitivity of this considerable amount (23-35 kgDVS/adt in total) to various factors is discussed in this paper.

Environmental Monitoring↗

PubMed2003

Fate of effluent organic matter during soil aquifer treatment: biodegradability, chlorine reactivity and genotoxicity.

Hydrophobic acid (HPO-A) and transphilic acid (TPI-A) fractions of dissolved organic matter (DOM) were isolated from a domestic secondary wastewater effluent that was polished via soil aquifer treatment (SAT). Fractions were isolated using XAD resin adsorption chromatography from samples obtained along the vadose zone flowpath at a full-scale basin recharge facility in Tucson, Arizona. Changes in isolate character during SAT were established via biodegradability (batch test), specific ultraviolet light absorbance (SUVA), trihalomethane formation potential (THMFP), and Ames mutagenicity assays. The dissolved organic carbon (DOC) concentration decreased by >90% during SAT. A significant fraction (up to 20%) of isolated post-SAT HPO-A was biodegradable. The (apparent) refractory nature of DOM that survives SAT may be a consequence of low DOC concentration in groundwater as well as the nature of the compounds themselves. Specific THMFP (microg THM per mg DOC) of HPO-A and TPI-A varied little as a consequence of SAT, averaging 52 and 49 microg THM per mg DOC, respectively. The nonbiodegradable fractions of HPO-A and TPI-A exhibited higher reactivities: 89 and 95 microg THM per mg DOC, respectively. Genotoxicity of HPO-A (on a per mass basis) increased after SAT, suggesting that responsible compounds are removed less efficiently than bulk organics during vadose zone transport.

Arizona↗

PubMed2004

Influence of suspension viscosity and colloidal particles on permeability of membrane used in membrane bioreactor (MBR).

In this study, pilot scale experiments were carried out to examine membrane fouling occurring in membrane bioreactors (MBR) with or without pre-treatment (coagulation/sedimentation). Especially, the influence of suspension viscosity and dissolved organic matter (DOM) on membrane fouling was investigated. The pre-coagulation/sedimentation process improved the performance of a MBR in terms of membrane permeability by controlling irreversible fouling and formation of thick cake layer. The upper limit of MLSS concentration for an efficient operation in MBR without pre-treatment was suggested to be around 10 g/L based on the measurement of suspension viscosity. In this study, it was difficult to directly relate membrane fouling to DOM detected in the membrane chamber. A series of laboratory scale dead-end filtration experiments was carried out to investigate which fractions in biomass suspension would be the most influential in the deterioration of membrane permeability. Based on the dead-end tests, it was shown that the deterioration of membrane permeability was mainly caused by the colloidal particle fraction in the biomass suspension.

Biomass↗

PubMed2004

[Fractionation and spectroscopic property of dissolved organic matters in soils].

Based on a modified Leenheer DOM fractionation sche me, fractionation of DOM from paddy soils was conducted byusing XAD-8 resin into hydrophobic bases (HOB), hydrophobic acids (HOA), acid-insoluble matter (AIM), hydrophobic neutrals (HON) and hydrophillic matter (HIM), and their structural characteristics were studied by means of elemental composition, FTIR and 1H-NMR spectroscopy. The fractionation scheme used here provided a preferable separation of the fractions in terms of hydrophobicity and a high recovery. Of the DOC extracted from the soils, the HOB was the least fraction, accounting for 0.73%-3.83%, and the HIM fraction was the largest, accounting for 36%-42%. The HON fraction represented 7%-15%. The relative content of the HOA plus AIM was about 50%. Separated by this technique, the large-chain alkylate and the major portion of the N components mainly characterized HON, while the HOA fraction contained a large amount of carboxyl groups but less amount of aromatic groups with a higher quantity of carbohydrates compared to that of FA. AIM fraction was dominated by high branched (n value) polyphenols and humus bound carbohydrates. HIM was characterized by considerable amount of carboxyl and carbohydrates.

Chemical Fractionation↗