ABSTRACT
Based on the actual operating conditions and data monitoring, the carbon emission characteristics of typical processes of a drinking water treatment plant (DWTP) in Tianjin were studied. The total carbon emission intensity measured by CO2-eq was 0.254 kg·m-3, and the proportion of carbon emissions from electricity consumption and reagent consumption was 81.76% and 9.15%, respectively. The key carbon emission sectors of electricity consumption were the water supply pump house, ultrafiltration membrane process, and inlet pump house, which accounted for 50.99%-73.51%, 17.64%-20.70%, and 17.97%-22.40% of the total carbon emission from electricity consumption in the DWTP, respectively. The contribution of sodium hypochlorite to the carbon emission of reagent consumption was 89.12%-90.30%, followed by ferric chloride, PAC, and ammonium sulfate. In the traditional water purification process, the carbon emission intensity of the process unit was in the order of inlet pump house > rapid filter > sedimentation tank. The order in the ultrafiltration membrane advanced treatment process was inlet pump house > ultrafiltration membrane > mechanical coagulation > clarification tank. The carbon emission intensity of the rapid filter process and the ultrafiltration membrane process were 0.070 9 kg·m-3 and 0.109 0 kg·m-3, respectively. The ultrafiltration membrane process could save 23% of the reagent consumption, and its carbon emission of electricity consumption was twice that of the traditional treatment process. The analysis of factors affecting carbon emission in key sectors showed that the raw water quality parameters such as turbidity, pH, ammonia nitrogen, temperature, etc., were significantly correlated with the carbon emission intensity of sodium hypochlorite. There was a significant linear regression relationship between ex-factory water pressure, daily water supply, and carbon emission intensity of the water supply pump house. The control measures of water quality and water pressure can effectively reduce the carbon emissions of the DWTP.
Subject(s)
Drinking Water , Water Purification , Carbon , Sodium Hypochlorite , Water Supply , UltrafiltrationABSTRACT
Background: Microbial dysbiosis in critically ill patients is a leading cause of mortality and septic complications. Probiotics and synbiotics have emerged as novel therapy on gut microbiota to prevent septic complications. However, current evidence on their effects is conflicting. This work aims to systematically review the impact of probiotics or synbiotics in critically ill adult patients. Methods: A comprehensive search of the PubMed, CBM, Embase, CENTRAL, ISI, and CNKI databases was performed to identify randomized controlled trials that evaluate probiotics or synbiotics in critically ill patients. The quality assessment was based on the modified Jadad's score scale and the Cochrane Handbook for Systematic Reviews of Interventions Version 5.0.1. The major outcome measure was mortality. Secondary outcomes included incidence of septic complications, sepsis incidence, length of intensive care unit (ICU) stay, incidence of non-septic complication, and ventilator day. Data synthesis was conduct by Review Manager 5.4. Results: A total of 25 randomized controlled trials reporting on 5049 critically ill patients were included. In the intervention group, 2520 participants received probiotics or synbiotics, whereas 2529 participants received standard care or placebo. Pooling data from randomized controlled trials demonstrated a significant reduction in the incidence of ventilator-associated pneumonia (VAP) in the treatment group [(risk ratio (RR) 0.86; 95% confidence interval (CI): 0.78-0.95; p < 0.003, I2 = 85%)]. However, in the subgroup analysis, the reduction of incidence of VAP was only significant in patients receiving synbiotics (RR = 0.61, 95% CI: 0.47-0.80, p = 0.0004, I2 = 40%) and not significant in those receiving only probiotics (RR = 0.91, 95% CI: 0.82-1.01, p = 0.07, I2 = 65%). Moreover, sepsis incidence of critically ill patients was only significantly reduced by the addition of synbiotics (RR = 0.41; 95% CI: 0.22-0.72, p = 0.005, I2 = 0%). The incidence of ICU-acquired infections was significantly reduced by the synbiotics therapy (RR = 0.72; 95% CI: 0.58-0.89, p = 0.0007, I2 = 79%). There was no significant difference in mortality, diarrhea, or length of ICU stay between the treatment and control groups. Conclusions: Synbiotics is an effective and safe nutrition therapy in reducing septic complications in critically ill patients. However, in such patients, administration of probiotics alone compared with placebo resulted in no difference in the septic complications.
ABSTRACT
The batch sorption methods were employed to investigate the sorption behavior of tetracycline (TC) on the activated sludge. It was shown that the mixed liquor suspended solids (MLSS) and the initial concentration of TC had great impacts on equilibrium time, adsorption capacity and adsorption rate. Compared with pseudo first-order model, pseudo second-order model showed the better agreement. At 10, 25 degrees C, the Langmuir model was the best isotherm to describe the experimental data for adsorption of TC on activated sludge, and the maximum adsorption capacities were 31.14, 70.95 mg x g(-1) respectively; at 40 degrees C, the linear isotherm confirmed the agreement. The data were also modeled by D-R isotherm to determine the type of adsorption. At 10 degrees C (E was 9.13 kJ x mol(-1)), the dominant type was physical, and at 40 degrees C (E was 7.07 kJ x mol(-1)), the dominant type was chemical. With the temperature increasing, the adsorption capacity increased. Ion exchange is one mechanism for adsorption of TC on activated sludge. When the initial concentrations of TC were 5, 10, 20 mg x L(-1), with the Na+ concentration increasing from 0 mol x L(-1) to 0.1 mol x L(-1), the adsorption capacities decreased by 15.32%, 15.00%, 20.12% respectively. The maximum adsorption capacity was got at pH 6 when pH varied from 5 to 10.