Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C1835664 (TOC)
 2,763 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Characteristics of pollutants from urban surface runoff were investigated. Two catchments with a seperated system in Macau were selected for sampling on rainfall events during the period of August to November, 2005. Water quality parameters such as pH, turbidity, TSS, COD, TOC, TN, TP, Zn, Pb, and Cu were analyzed. The results show that the commercial-residential urban catchment shows high level of COD, TN, TP, and the park urban catchment has high TN and TP concentration. From the pollutograph analysis, the peak of TSS, TN, TP concentration appears in the first and the third sample respectively in ELH and YLF catchments, and then the pollutants concentration tend to decrease. Regression analysis between TSS and TN & TP in two urban catchments resulted in a high value (R2 > 0.95) of the coefficient of determination R2 indicating a close relationship between soil losses and nitrogen & phosphorus discharged from surface runoff. The profile of TSS and COD discharged from surface runoff relates greatly to the surface flow change, whereas the surface flow change has little influence on the profile of TN and TP. The heavy metals such as Zn, Pb and Cu fluctuate with the continuous input of vehicles during rainfall events. Pollutants such as TSS, TN, COD discharged from surface runoff depend greatly on the dry periods and storms intensity in such two urban catchments.
 ...
PMID:[Characterization of urban surface runoff in two urban catchments in Macau]. 1711 27

Nitrification is a key step for reliable biological nitrogen removal. In order to enhance nitrification in the activated sludge (AS) process, membrane-attached biofilm (MAB) was incorporated in a conventional activated sludge tank. Simultaneous organic carbon removal and nitrification of the MAB incorporated activated sludge (AS + MAB) process was investigated with continuous wastewater treatment. The effluent TOC concentration of AS and the AS + MAB processes were about 6.3 mg/L and 7.9 mg/L, respectively. The TOC removal efficiency of both AS and AS + MAB were above 95% during the wastewater treatment, indicating excellent organic carbon removal performance in both processes. Little nitrification occurred in the AS process. On the contrary, successful nitrification was obtained with the AS + MAB process with nitrification efficiency of about 90%. The volumetric and surface nitrification rates were about 0.14 g/Ld and 6.5 g/m2d, respectively. The results clearly demonstrated that nitrification in the conventional AS process was boosted by MAB. Furthermore, the microfaunal population in the AS + MAB process was different from that in the AS process. The high concentration of rotifers in the AS + MAB process was expected to decrease the generation of excess sludge in the process.
 ...
PMID:Boosting nitrification by membrane-attached biofilm. 1716 50

Fresh leachate and effluents samples were collected from the holding tank, anaerobic, anoxic, and aerobic lagoons at Shanghai Laogang Refuse Landfill, the largest landfill in China with a placement scale of 9000 t refuse per day. To characterize the difference in leachate along the treatment processes, especially the information about size distribution of colloids in those leachate, the organic matters were size-fractioned into suspended particles (SP, >1.2 microm), coarse colloids (CC, 1.2-0.45 microm), fine colloids (FC, 0.45 microm to 1 kDa MW, 1 Da=1/16 O atomic mass unit), and dissolved organic matters (DM, <1 kDa MW) using micro-filtration and ultra-filtration membranes in order. The parameters, such as COD (chemical oxygen demand), TOC (total organic carbon), TS (total solid), pH, TP (total phosphate), TN (total nitrogen), FS (fixed solid), NH4+, IC (inorganic carbon), TC (total carbon), color, turbidity and conductivity in the filtrates resulting from sequential filtration of leachate, were then determined, and quantitative relationships between these parameters and the membrane molecular sizes used were established. Typically, the total removal of COD, NH4+, conductivity and P were found to be 75%, 75%, 42% and 85%, respectively, after the biological treatment processes used at Laogang Refuse Landfill. Dissolved fractions were predominant in fresh leachate and in effluents from treatment processes in terms of TOC with a content of over 47%. The molecular weight (MW) percentage distribution in leachate varied as the leachate was treated in the biological treatment stages. The percentages of TOC of fine colloid fractions increased from 6% to 38% while those of dissolved fractions decreased from 78% to 47%. TN in leachate also predominated in the dissolved fraction, occupying over 58%, while those TP in leachate were combined with the SS and CC fractions. The ratios of ortho-phosphate/TP and NH4+/TN in leachate and effluents were over 50% and 80%, respectively.
 ...
PMID:Size-fractionation and characterization of refuse landfill leachate by sequential filtration using membranes with varied porosity. 1729 64

River and sediment have unique carbon dynamics and are important sources of the dominant greenhouse gases (GHG), carbon dioxide (CO2) and methane (CH4). To understand the relationship between CO2/CH4 emissions and water quality/sediment characteristics, we have investigated critical parameters in the river water. Eight parameters of water quality (dissolved oxygen, oxidation-reduction potential [ORP], chemical oxygen demand, biochemical oxygen demand [BOD5], suspended solid, nitrate [NO3-], NH4+, and bacteria) and four sediment characteristics (total organic carbon [TOC], total nitrogen [T-N], NO3-, and ammonium [NH4+]) were measured in two of the larger rivers in Taiwan, and relevant environmental conditions were recorded. The experimental results indicated that CO2 emissions from the river were mainly affected by BOD5 concentrations and the levels of bacteria. CH4 emissions, on the other hand, were greatly affected by the ORP in the river. The correlation between CO2 emissions and sediment characteristics was insignificant (R2 < 0.3). However, TOC and T-N in the sediment may lead to increases in CH4 emissions into the atmosphere. A deeper analysis of the relationship between the different parameters and GHG emissions by ANOVA and the multiple regression method revealed that CO2 emission (y) was significantly related to bacteria number (x1) and BOD concentration (X2). The regression equation takes the form y = 0.00032x1 + 3.18089x2 + 25.37304. Also, the regression relationship between CH4 emission (y) and ORP (x) in the river can be described as y = -0.825216x + 169.02257. The relationship between CH4 emission and sediment characteristics may be described as y = 5.073962x1(TOC) + 2.871245x2(T-N) - 12.3262. Extra sampling data were collected to examine the feasibility of the developed multiple regression equations. The experimental results suggest that the emissions of such GHGs as CO2 and CH4 from rivers can be predicted using the regression equations developed here. Moreover, the emissions may be reduced by manipulating the proper factors.
 ...
PMID:Relationship between carbon dioxide/methane emissions and the water quality/sediment characteristics of Taiwan's main rivers. 1738 98

Submerged membrane bioreactors (MBRs) have been gaining in popularity in various types of wastewater treatment. One drawback of submerged MBRs is difficulty in removing nitrogen as they are accompanied with intensive aeration inside the reactor and therefore principally operated under aerobic conditions. In order to address this problem, a simple modification for submerged MBRs, insertion of baffles to create alternative aerobic/anoxic conditions, was proposed. In this study, the performance of the proposed baffled membrane bioreactor (BMBR) was investigated based on a pilot-scale experiment using a real municipal wastewater. With appropriate operating conditions, the BMBR could remove more than 70% of total nitrogen contained in the feed water without any external carbon source. The BMBR demonstrated a good treatment performance in terms of TOC and phosphorus removal as well. Increase of trans-membrane pressure difference was subtle, which might be attributed to the alternative creation of aerobic/anoxic conditions.
 ...
PMID:Modification of submerged membrane bioreactors (MBRS) by inserting baffles: pilot scale study. 1750 28

Total trihalomethane (TTHM) concentrations were determined in three chlorinated effluents (i.e. secondary and tertiary) from full-scale wastewater treatment plants (WWTP) in NE Spain over a 2-year monitoring period (May 2003-February 2005). Low TTHM concentrations (2-30 microg L(-1)), according to international standards for drinking water (80-150 microg L(-1)), were obtained in all samples analysed. The effects of (a) ammonia nitrogen and bromide concentrations, (b) UV light exposure, (c) tank storage, and (d) water temperature were evaluated. Two chlorination strategies were adopted: low chlorine dosages (2-5 mg Cl2 L(-1)) and a high-chlorine dosage (16 mg Cl2 L(-1)). The effects of storing chlorinated reclaimed water and of UV light exposure before chlorination were also evaluated. Samples collected over the 2-year monitoring period offered the possibility to assess the numerous variables affecting THM formation. A statistical evaluation of Platja d'Aro WWTP data set shows a low TTHM formation in the presence of high ammonia nitrogen concentration (p<0.05). That result can be attributed to the formation of chloramines by reaction with added chlorine, at doses below breakpoint chlorination. An increase in TTHM concentration in the presence of bromide (0-1 mg L(-1)) was also recorded (p<0.05). In contrast to published reports, TOC had a negative effect on TTHM formation. COD and turbidity had no statistical significance on TTHM formation. As expected, chlorination promoted TTHM formation in the three water reclamation plants monitored. Nevertheless, no statistical difference was observed when chlorinated effluents were kept in storage tanks. Exposure to UV light did not affect either formation or removal of TTHM. The relative production of TTHM during warm and cold seasons was also evaluated. TTHM production decreased with higher temperatures, but that could be attributed to the increase of ammonia nitrogen concentration observed during the warm summer seasons.
 ...
PMID:Trihalomethane occurrence in chlorinated reclaimed water at full-scale wastewater treatment plants in NE Spain. 1758 88

An aerobic granular sludge membrane bioreactor(GMBR) had been stably operated for 71 days, and it showed good organics removal and simultaneous nitrification and denitrification (SND) performances. TOC, ammonium and total nitrogen removal efficiencies of GMBR remained 84.7% - 91.9%, 85.4% - 99.7% and 41.7% - 78.4% respectively as influent TOC were 56.8 - 132.6 mg/L and ammonium nitrogen were 28.1 - 38.4 mg/L. Moreover, further batch tests of different size sludge revealed that floclike sludge nearly had not SND ability, the SND performances of GMBR was mostly come from granular sludge, and denitrification rate and total nitrogen removal efficiencies under aerobic condition increased with sludge size increased. Analyzing the morphology and section characteristics of granular sludge under scan electron microscope, the SND process was also described.
 ...
PMID:[Characteristics of nitrogen removal in aerobic granular sludge membrane bioreactor]. 1763 28

Variations of delta 13C(org) and delta 15N values, C/N ratios, TOC and TN contents in Chaohu Lake sediments reflect the sources of organic matter in lake sediments, evolution of lake productivity and the eutrophic status in Chaohu Lake during last 100 years. Our results suggest that the sedimentary organic matter was derived mainly from aquatic algae and partly from land matter. However, the input of the pollutants from city and agriculture into the lake could not be neglected. Two stages can be found in the sediments cores according to the profiles of delta 13C(org), delta 15N values, TOC and TN contents. Below 10cm, delta 13C(org) values vary between - 21.74 per thousand and - 19.34 per thousand. Nitrogen fixing and non-nitrogen fixing phytoplankton coexist together. Two cores show different nutrition processes. Above 10cm, in both profiles, the values of delta 13C(org) start to decrease sharply, but delta 15N, TOC and TN increase. The construction of Chaohu Gate leads to the enhancement of lake productivity and development of eutrophication.
 ...
PMID:[Record of ecosystem evolvement processes provided by delta 13C(org) and 6 delta 15N values in Chaohu Lake sediments]. 1767 46

This study describes the degradation of nitrogen-heterocyclic compounds (NHCs) by anodic oxidation and electro-Fenton. Using indole as a model nitrogen-heterocyclic compound, the removal of indole reached 68% and 97% by anodic oxidation and electro-Fenton, respectively, while the decay of TOC was 15% and 38% correspondingly. By the analysis of ultraviolet-visible spectra and liquid chromatography/mass spectrum, the degradation mechanism of indole by electro-Fenton was proposed as hydroxyl oxidation and anodic oxidation. The degradation of other NHCs including quinoline, isoquinoline and pyridine by anodic oxidation and electro-Fenton revealed the same sequence: quinoline approximately equal isoquinoline > indole >> pyridine. A significant correlation between ln k (natural logarithm of rate constants) and E(LUMO) (the energy of the lowest unoccupied molecular orbit) was obtained by quantitative structure-activity relationship analysis. Degradation of coking plant wastewater showed the removal of COD and TOC were 42% and 22% respectively after 180 min treatment by electro-Fenton.
 ...
PMID:Degradation of nitrogen-heterocyclic compounds by anodic oxidation and electro-Fenton methods. 1771 Sep 20

Biosolids from the WWTP of Thessaloniki were examined for the leaching of phosphorus (as PO4(3-) -P), nitrogen (as NH4+ (-N) and NO3- (-N)), and organic matter (as TOC and COD), using two tests: (1) a pH static leaching test and (2) a characterization test, relating contaminant release to the liquid to solid (L/S) ratio. Moreover, a Microtox toxicity test was conducted, to examine the pH dependency of the toxicity of the sludge leachate on the Vibrio fischeri bacterium. Maximum phosphorus release was observed at pH < 3 and at pH > 10. Ammonium nitrogen exhibited maximum leachability at near neutral pH conditions, while nitrate nitrogen exhibited a mild increase in the leachate, as the leachant pH increased from 2 to 12. Both TOC and COD exhibited an increase in the leachate concentration, as the leachant pH was increased from 2 to 12. Ecotoxicological analysis showed that maximum toxicity occurred at very low and very high pH-conditions. As liquid-to-solid ratio increased, the leachate concentration (in mg/l) of all parameters studied decreased. The results of the study were used to conduct a release assessment estimate for the case of Thessaloniki.
 ...
PMID:Leaching of nitrogen, phosphorus, TOC and COD from the biosolids of the municipal wastewater treatment plant of Thessaloniki. 1776 30


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>