ABSTRACT
In this paper, the change characteristics of DOM (dissolved organic matter) and acid production characteristics of anaerobic fermentation in waste activated sludge(WAS) pretreated with rhamnolipid (RL) were studied. The results showed that RL at the dose of 80â mg/gTS could significantly promote the disintegrating of EPS (extracellular polymers) and cell wall in WAS, and a large number of proteins and carbohydrates were dissolved. Three dimensional fluorescence parallel factor analysis showed that the addition of RL enhanced the dissolution and biodegradability of humus-like substances. LC-OCD (Liquid chromatography - organic carbon detection) analysis showed that RL promotes the dissolution of biodegradable components such as Biopolymer, Building Blocks and LMW Neutrals, and ensures the increase of VFA (volatile fatty acids) production in the process of anaerobic fermentation. Under the RL dose of 80â mg/gTS, the maximum VFA production of WAS was obtained at 108â h of anaerobic fermentation, which was 2699.39â mg/L. Acetic acid and propionic acid were the main components in the WAS fermentation broth pretreated by RL. The concentration of butyric acid increased with the increase of RL dose. The RL dose can significantly affect the composition of VFA in WAS fermentation broth.
ABSTRACT
This paper studied the effect of thermal-alkali with rhamnolipid coupling pretreatment waste activated sludge (WAS) on the dissolution and acid production of organic matter. The results showed that when the dosage of rhamnolipid (RL) was 40 mg/g vs, the dissolution rate of soluble Chemical oxygen demand (SCOD) and soluble carbohydrate (SC) was the highest, and the concentration of soluble protein (SP), biopolymer and neutral low molecular substances was the highest. Three-dimensional fluorescence parallel factor analysis found that the addition of rhamnolipid promoted the formation of fulvic acids. When the dosage of rhamnolipid was 60 mg/g vs, the highest peak concentration of volatile fatty acids (VFAs) reached 3.5 days. The type of fermentation acid was butyric acid. The higher cracking rate and higher acid production rate showed that thermal-alkali with rhamnolipid had better acid production performance than thermal-alkali pretreatment sludge, but the amount of rhamnolipid affected the fermentation type.
Subject(s)
Alkalies , Sewage , Fatty Acids, Volatile , Fermentation , Glycolipids , Hydrogen-Ion Concentration , SolubilityABSTRACT
OBJECTIVE: The purpose of this study was to evaluate the effects of high-intensity interval training (HIIT) and moderate-intensity continuous training (MICT) on cardiovascular disease (CVD) risk factors in adults with overweight and obesity. METHODS: Twenty-two articles were included by searching six databases, the total number of subjects was 620 in these articles. Outcomes were synthesised using a random-effects meta-analysis of the Standardized mean difference (SMD) in CVD risk factors. RESULTS: HIIT and MICT resulted in statistically significant reductions in Weight, BMI, fat%, total cholesterol(TC), and improvement in VO2max. Compared with MICT, subgroup of durations of HIIT training interval ≥2 min can significantly increase VO2max (SMD = 0.444, 95% CI:0.037~0.851,P = 0.032), subgroup of energy expenditure of HIIT equal to MICT can significantly increase VO2max (SMD = 0.399, 95% CI:0.106~0.692,P = 0.008). CONCLUSIONS: HIIT appears to provide similar benefits to MICT for improving body composition, VO2maxand TC, but HIIT spent less time than MICT by 9.7 min on one session. HIIT is superior to MICT in improving cardiopulmonary fitness when durations of HIIT training interval ≥2 min or energy expenditure of HIIT same as MICT. PROSPERO ID: CRD42016045835.
