Biomedical subjects

Suzelle Barrington

Publications and source records attributed to Suzelle Barrington.

7 recordsLinked to original sources

PubMed2006

Biodegradation of pentyl amine and aniline from petrochemical wastewater.

The objectives of the project were to isolate a bacterial strain capable of degrading pentyl amine and aniline and to define the optimal pentyl amine and aniline degradation conditions for this bacterial strain. The bacterial strain was isolated from activated sludge obtained from a Northeastern China treatment facility for petrochemical wastewater rich in pentyl amine and aniline. Once the strain was isolated, five triplicate (5) batch tests were used to establish the conditions for maximum pentyl amine and aniline degradation, by varying one at a time the following five factors: temperature, pH, reaction time, pollutant concentrations and aeration rate. In a final test, oil refinery sludge was inoculated with the strain and tested for the degradation of pentyl amine and aniline under optimal conditions, while observing the degradation pathway of pentyl amine and aniline. The isolated strain, PN1001, is a member of the Pseudomonas species and it was capable of degrading pentyl amine and aniline. The optimal reactor conditions for the degradation of a mixture of pentyl amine and aniline, at a concentration ranging between 150 and 200mg/L, were found to be 30 degrees C at a pH of 7.0, under a reaction time of 24h and a maximum solution dissolved oxygen level of 6 mgO(2)/L. Under such conditions, the strain PN1001 degraded 93% and 89% of the pentyl amine and aniline, respectively, aniline being more toxic and demonstrating a more complex degradation pathway. The strain PN1001 degraded more contaminants when both were present because of the pi and sigma electron cloud coordination functions of aniline and pentyl amine, respectively, presumed to reduce the toxic effect of aniline. Once inoculated with the strain, oil refinery sludge degraded 93% and 88% of the pentyl amine and aniline, compared to the strain alone which degraded 72% and 82%, likely because of the sludge's buffering effect against the toxic environment.

Amines↗

PubMed2006

Predicted growth of world urban food waste and methane production.

Landfill gas emissions are one of the largest anthropogenic sources of methane especially because of food waste (FW). To prevent these emissions growing with world population, future FW best management practices need to be evaluated. The objective of this paper was therefore to predict FW production for 2025 if present management practices are maintained, and then, to compare the impact of scenario 1: encouraging people to stay in rural areas and composting 75% of their FW, and; of scenario 2, where in addition to scenario 1, composting or anaerobically digesting 75% of urban FW (UFW). A relationship was established between per capita gross domestic product (GDP) and the population percentage living in urban areas (%UP), as well as production of municipal solid waste (MSW) and UFW. With estimated GDP and population growth per country, %UP and production of MSW and UFW could be predicted for 2025. A relatively accurate (R(2) > 0.85) correlation was found between GDP and %UP, and between GDP and mass of MSW and FW produced. On a global scale, MSW and UFW productions were predicted to increase by 51 and 44%, respectively, from 2005 to 2025. During the same period, and because of its expected economic development, Asia was predicted to experience the largest increase in UFW production, of 278 to 416 Gkg. If present MSW management trends are maintained, landfilled UFW was predicted to increase world CH4 emissions from 34 to 48 Gkg and the landfill share of global anthropogenic emissions from 8 to 10%. In comparison with maintaining present FW management practices, scenario 1 can lower UFW production by 30% and maintain the landfill share of the global anthropogenic emissions at 8%. With scenario 2, the landfill share of global anthropogenic emissions could be further reduced from 8 to 6% and leachate production could be reduced by 40%.

Air Pollutants↗

PubMed2004

Copper adsorption with Pb and Cd in sand-bentonite liners under various pHs. Part II. Effect on adsorption sites.

The project examined the effect of Pb and Cd on Cu adsorption using sand liners containing 0, 5, and 10% sodium bentonite and exposed to metal solutions at three pH levels (3.7, 5.5, and 7.5). Aliquots of 2 g of liner material were exposed in duplicate, for 14 days, to solutions containing Cu alone or Cu with either Pb or Cd. Selective sequential extraction (SSE) was used to quantity the Cu adsorbed by each liner particle adsorption site (exchangeable, carbonate and hydroxide, oxides and residual). The results indicated that two main factors affected liner material behavior in adsorbing Cu, besides Cd and Pb competition: pH either above or below 6.5; liner cation exchange capacity (CEC) greater or equal and greater than the solution cation equivalence. In general, the liner carbonate and hydroxide fractions precipitated the greatest amount of Cu, under all environmental conditions while the exchangeable, oxide and residual adsorbed more or less the same amount. Lead, and to a lesser extent Cd, significantly increase the mobility of Cu, by competing especially for the exchangeable sites. While Cd also competed against Cu for oxide adsorption, Pb competes for calcium and hydroxide precipitation. Lead, and to a lesser extent Cd, competed especially for the exchangeable site where the adsorption is more dynamic, and less for the more permanent adsorption sites, involving precipitation, and electrostatic bonding.

Adsorption↗

PubMed2004

Copper adsorption with Pb and Cd in sand-bentonite liners under various pHs. Part I. Effect on total adsorption.

Municipal solid wastes could be segregated based on their specific heavy metal content and disposing of them in separate landfill cells. Therefore, the objective of the project was to investigate the interaction between copper (Cu) and either lead (Pb) or cadmium (Cd) using equilibrium batch adsorption experiments. A first test consisted of soaking three types of sand-bentonite liner samples (0, 5, and 10% bentonite) with a respective cation exchange capacities (CEC) of 2, 6.4, and 10.8 cmol(+)/kg in one of nine solutions consisting of a combination of three pH levels (3.7, 5.5, and 7.5) and three heavy metal solutions (Cu alone, Cu with Cd, Cu with Pb) each offering a respective heavy metal equivalence of 1, 2, and 2cmol(+)/kg of liner. A second test set consisted in soaking 5% bentonite liner samples in three solutions at a pH of 3.7, with either Cu alone or with Pb or Cd, at 4.8 cmol(+)/kg of liner. For up to 14 days, duplicate samples were sacrificed to determine the supernatant Cu level and pH. The results indicated that under acidic conditions (pH< 6.5), the liner bentonite content, the solution pH and the presence of Pb or Cd significantly influenced Cu adsorption. Lead, and to a lesser extent Cd, competed with Cu for adsorption sites. Under alkaline conditions (pH> 6.5), carbonate and hydroxyl precipitation governed and masked the Pb and Cd competition. Thus, at low pH, limiting the presence of Pb in landfill leachate can improve Cu adsorption.

Adsorption↗

PubMed2003

Compost convective airflow under passive aeration.

For composting, passive aeration can save energy costs while being just as efficient as forced or active aeration. Passive aeration requires the proper design of aeration ducts, and thus, the proper prediction of the convective airflow rates created by the temperature differential between the compost and the ambient air. To establish such relationship, the temperature and convective air flow regimes of composts were investigated using three bulking agents (wood shavings, hay and straw), each at three moisture contents (MC-60%, 65% and 70%) spanning the normal values. All bulking agent and aeration treatments were aerated in duplicate under passive and active regimes. Laboratory vessels of 105 L were used for all treatments. Passive aeration treatments produced temperatures above 57 degrees C, as did the treatments actively aerated at 4 mg of air s(-1) kg(-1) of initial dry compost material. Compost MC had an effect only on the peak compost temperature, occurring between day 2 and 6. After 6 days of composting, MC no longer had any effect on temperature regime because of the loss of moisture by each mixture. A relationship was established between the Grasholf number (Gr-ratio of buoyancy to viscous forces) and the convective airflow rates, to size the aeration ducts for passive aeration. In general, convective airflow rates ranged from 1.5 to 0.7 mg of dry air s(-1) kg(-1) of initial compost dry matter, from day 0 to day 20, respectively, and for all compost treatments. This airflow rate sizes the aeration ducts installed under compost piles for passive aeration. As compared to straw where airflow rate dropped over a given level of Gr, wood shavings and hay were found to be more effective as bulking agents, as their airflow rate increased constantly with Gr.

Air Movements↗

PubMed2002

Effect of carbon source on compost nitrogen and carbon losses.

The effect of C source on N losses by volatilization during composting was measured using four bulking agents, each at three humidity levels and composted in duplicate under passive and active aeration. The bulking agents were pine shavings alone and corrected with soybean, chopped grass hay alone and corrected with urea, long (unchopped) wheat straw and chopped oat straw. The readily available C of each bulking agent was determined by analyzing for BOD5. In 105 l laboratory vessels, the bulking agents were mixed with liquid swine manure and tap water for a C/N of 20 and three humidity levels of 60%, 65% and 70%. While being aerated actively or passively, the mixtures were composted for 21 days. Their initial and final C and N contents were measured to conduct a mass balance analysis and calculate C and N losses. C and N losses were compared to bulking agent BOD5. N losses were compared to C losses. The humidity level and aeration regime had no effect on C and N losses but the N losses were correlated to C losses and only the C losses could be correlated to the BOD5 of the bulking agent. Thus, the N losses are related not only to the availability of C but also to the extent of composting. A relationship established between N and C losses indicated that 85% of the initial total N of the compost was available for microbial degradation and that 70% of the available C was lost as CO2 during the immobilization process.

Air Movements↗

PubMed2002

Precipitation of swine and cattle manure phosphorous using limestone dust.

The effectiveness of SPS and PULPRO, fine limestone dusts, in precipitating swine and dairy manure phosphorous (P) was determined in the laboratory. Both manures were sieved before being treated with limestone, to reproduce the treatment of mechanically separated manure and to observe the precipitation effect of limestone without that of the large manure solid particles. P precipitation was optimized by varying precipitation conditions (propeller blade speeds, mixing time and limestone levels) and limestone particle size. P precipitation was optimized using a propeller blade mixing speed of 0.3 m s(-1) for at least 5 minutes, using 3% limestone (dry limestone mass over wet manure mass). In terms of particle size, PULPRO 20 (limestone with a particle size of 0.02 mm) produced the most P precipitation and the smallest volume and mass of sludge, as compared to PULPRO 10, PULPRO 3 and SPS (limestone with a particle size of 0.01, 0.003 and 0.3 to 0.003 mm, respectively). For both 9.5% TS (total solids) dairy and 8.8% TS swine manure, mechanical separation followed by limestone precipitation concentrated 90% of manure TS and TP in a sludge volume representing 45% of the initial raw manure mass.

Animals↗