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)

A method is described to evaluate two methods of phosphorus (P) management in lakes using aluminum sulfate (alum)--in-lake and tributary (inflow) treatment--and compare the resulting in-lake P levels. For in-lake treatment, a technique is described to calculate the optimum alum dose based on measurement of "mobile P" in lake sediments. Mobile P is defined as loosely sorbed and Fe-P, the fraction of sediment P subject to release under anoxic conditions. A linear relationship (r2 = 0.90) was found between P-release rate and the mobile-P content in sediment cores. Addition of alum to aliquots of sediment showed predictable relationships between (i) alum dose and aluminum-bound P (Al-P) formed and (ii) mobile-P loss and Al-P formation. The decrease in sediment P release that would result from in-lake alum treatment was estimated from the residual mobile P after treatment. A method also is presented to estimate the amount of alum needed to bind potentially mineralizable sediment organic P. For inflow treatment, jar tests with urban runoff in metropolitan St. Paul and Minneapolis, Minnesota (USA) were used to study effects of alum dose on P removal from water. With sufficient mixing, a dose of 8 mg AlL(-1) reduced total P (TP) and soluble reactive P to low levels regardless of pH, TSS, and TOC, but doses <or= 4 mg AlL(-1) did not significantly reduce TP compared with settling alone. A modeling approach is described to compare the effects of inflow and in-lake treatment, and a case study is developed to illustrate the approach for typical eutrophic lakes.
 ...
PMID:A method for comparative evaluation of whole-lake and inflow alum treatment. 1729 15

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

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

Domestic wastewater from a new city district in Stockholm has been treated by an anaerobic membrane bioreactor (AMBR) followed by reverse osmosis (RO). The main objectives were to study the gas production, the reduction of organic matter and nutrient recovery. The AMBR was operated at 22 degrees C (equal to the average temperature in the influent) and a hydraulic retention time of 0.6 d. The results show that the reduction of organic matter, nitrogen and phosphorus over the AMBR was approximately 92, 9 and 9%, respectively. A stable gas production was registered throughout the evaluation period. The overall removal efficiency, i.e. including the RO, was >99% for TOC, >91% for Kj-N and about 99% for P. Adding a reverse osmosis (RO) unit to the AMBR makes it possible to produce a concentrated, nutrient rich product well suited for agricultural use. The quality of the concentrate is, in terms of nutrient concentration and heavy metal content, similar to source separated human urine, i.e. nitrogen content about 3 g N/L and <2 mg Cd/kg P. However, addition of acid is required to prevent precipitation/fouling of the RO. The total electricity use for operation for the system, including the RO-unit, is estimated to be 3-6 kWh/m3.
 ...
PMID:Wastewater treatment with anaerobic membrane bioreactor and reverse osmosis. 1788 55

By seeding aerobic granular sludge cultivated from artificial wastewater, an anaerobic/aerobic SBR was applied to treat domestic sewage of high COD, TN and SS. The stability of granular sludge and the removal of organic pollutants, nitrogen and phosphorus of domestic sewage were investigated. After one month incubation, the reactor had good pollutant removal performances and run stably. The ratio of granular sludge to total suspended solids was over 68% all along. The sludge concentration was 5 000 - 6 000 mg/L and SVI value was 20 - 35 mL/g. After three months operation, most of the granules were over 1.25 mm instead of 0.6 - 0.9 mm in the beginning. During the stable operation phase of the granular sludge SBR, the average removal efficiencies of COD, TOC, phosphate, ammonium nitrogen, total nitrogen, SS were 83.04%, 70.41%, 94.30%, 86.51%, 41.82% and 85.89%, respectively. Analysis of the pollutant removal in typical cycle showed that the granular sludge had good simultaneous phosphorus and nitrogen removal performance.
 ...
PMID:[Simultaneous phosphorus and nitrogen removal of domestic sewage with aerobic granular sludge SBR]. 1792 94

Vertical and temporal distributions of N and P in soil solution in aquatic-terrestrial ecotone (ATE) of Taihu Lake were investigated, and the relations among N, P, ORP (oxidation reduction potential), TOC, root system biomass and microorganism were studied. As a whole, significant declines in TN, NO3- -N, DON (dissolved organic nitrogen) and TP concentration in soil solution have occurred with increase of the depth, and reached their minima at 60 cm depth, except for NH4+ -N, which increased with depth. The concentration of TP increased gradually from spring to winter in the topsoil, the maximum 0.08 mg/L presented in the winter while the minimum 0.03 mg/L in spring. In the deeper layer, the concentration value of TP fluctuated little. As for the NO3- -N, its seasonal variation was significant at 20 cm depth, its concentration increased gradually from spring to autumn, and decreased markedly in winter. Vertical and temporal distribution of DON is contrary to that of NO3- -N. The results also show that the variation of N and P in the percolate between adjacent layers is obviously different. The vertical variation of TN, TP, NO3- -N, NH4+ -N and DON is significant, of which the variation coefficient of NO3- -N along the depth reaches 100.23%, the highest; while the variation coefficient of DON is 41.14%, the smallest. The results of correlation analysis show that the concentration of nitrogen and phosphorus correlate significantly with TOC, ORP, root biomass and counts of nitrifying bacteria. Most nutrients altered much from 20 to 40 cm along the depth. However, DON changed more between 60 and 80 cm. Results show that soil of 0-60 cm depth is active rhizoplane, with strong capability to remove the nitrogen and phosphorus in ATE. It may suggest that there exists the optimum ecological efficiency in the depth of above 60 cm in reed wetland. This will be very significant for ecological restoration and reestablishment.
 ...
PMID:Vertical and temporal distribution of nitrogen and phosphorus and relationship with their influencing factors in aquatic-terrestrial ecotone: a case study in Taihu Lake, China. 1796 41

This paper evaluated the performance and suitability of a resources and nutrients oriented decentralized greywater treatment system which uses a submerged spiral wound module. This greywater treatment system is aimed at treating and recovering the resources present in the wastewater. The study revealed that the UF membrane filtration system was able to maintain a permeate flux between 6 and 10 L/m2/h. TOC can be reduced from the influent value of 161 to 28.6 mg/L in the permeate, meaning an average elimination rate of 83.4%. In addition, soluble nutrients such as ammonia and phosphorus can pass through the UF membrane and remain in the permeate. The total nitrogen and total phosphorus in the permeate were 16.7 and 6.7 mg/L respectively. The permeate was low in turbidity (below 1 NTU) and free of suspended solids and E. coli and had an excellent physical appearance. The permeate can be used in gardening and agriculture for irrigation and soil fertilization or alternatively for toilet flushing after disinfection. The retentate generated in this system can be treated with blackwater and kitchen waste in an anaerobic digester at a later stage for producing biogas or compost.
 ...
PMID:Resources and nutrients oriented greywater treatment for non-potable reuses. 1858 76

The equilibrium phosphate concentration (EPC0) of the Yellow River bed sediments has been measured, which was used to predict whether bed sediments are acting as a source or sink of soluble reactive phosphate (SRP). The modified Langmuir isotherm equation was used to describe phosphate (P) sorption on the Yellow River sediments. The maximum P sorption capacity (PAC) and P-binding energy constant (k) were obtained by the modified Langmuir isotherm model. Native adsorbed exchangeable phosphorus (NAP), the EPC0, and partitioning coefficients (Kp) were subsequently calculated by the corresponding formulae. The influence of pH values and ion strength were evaluated. All the EPC0 s are higher than the P concentration in the overlying water, indicating a potential source of phosphate from the sediments. PAC is linearly related to the contents of TOC of the sediment. The sorption capacity of P increased rapidly with pH below 6.0, and then reached a plateau between pH 6.0 to 9.7, and finally maintained at a slightly higher level from pH 9.7 to 12.0.The adsorption of P by the sediment decreased with the increase in Ca2+ ionic strength.
 ...
PMID:[Phosphate sorption characteristics onto sediments in the middle and lower reaches of the Yellow River]. 1883 62

The results of an investigation characterizing the nutrients and suspended solids contained in stormwater from Kranji Catchment in Singapore are reported in this paper. Stormwater samples were collected from 4 locations and analyzed for the following eleven analytes: TOC, DOC, TN, TDN, NH(4)(+), NO(2)(-)+NO(3)(-) (NO(x)), TP, TDP, OP, SiO(2) and TSS. Stormwater was sampled from catchments with various proportions of rural and urban land use, including forested areas, grassed areas, agricultural and residential and commercial areas. The event mean concentrations (EMCs) of nutrients and TSS from sampling stations which have agricultural land use activities upstream were found to be higher. Comparison of site EMCs (SMCs) with published data showed that the SMCs of the nutrients and TSS are generally higher than SMCs reported for forested areas but lower than published SMCs for urban areas. Positive correlations (p<5%) were found between loading and peak flow at locations most impacted by ubanisation or agricultural activities. Correlation between loading and rainfall variables was less distinct. EMC was found to correlate less with rainfall and flow variables compared to pollutant loading. Unlike loading, no consistent pattern exists linking EMC to any particular storm or flow variable in any of the catchments. Lastly, positive correlations were obtained between the particulate forms of nitrogen and phosphorus and TSS.
 ...
PMID:Nutrients and suspended solids in dry weather and storm flows from a tropical catchment with various proportions of rural and urban land use. 1966 Aug 49

High rate composting studies on institutional waste, i.e. vegetable wastes, tree leaves, etc., were conducted on a demonstration-scale (3.5 m(3)) rotary drum composter by evaluating changes in some physico-chemical and biological parameters. During composting, higher temperature (60-70 degrees C) at inlet zone and (50-60 degrees C) at middle zone were achieved which resulted in high degradation in the drum. As a result, all parameters including TOC, C/N ratio, CO(2) evolution and coliforms were decreased significantly within few days of composting. Within a week period, quality compost with total nitrogen (2.6%) and final total phosphorus (6 g/kg) was achieved; but relatively higher final values of fecal coliforms and CO(2) evolution, suggested further maturation. Thus, two conventional composting methods namely windrow (M1) and vermicomposting (M2) tried for maturation of primary stabilized compost. By examining these methods, it was suggested that M2 was found suitable in delivering fine grained, better quality matured compost within 20 days of maturation period.
 ...
PMID:Rotary drum composting of vegetable waste and tree leaves. 1967 65


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