pH regulated potassium ferrate oxidation promotes acetic acid yield and phosphorous recovery rate from waste activated sludge.

To improve the dose efficiency of K2FeO4 in waste activated sludge (WAS) treatment, pH regulation on K2FeO4 pretreatment and acidogenic fermentation was investigated. Four pretreatments were compared, i.e. pH3 + 50 g/kg-TS, pH10 + 50 g/kg-TS, neutral pH + 50 g/kg-TS and neutral pH + 100 g/kg-TS (without pH adjustment). The higher short chain fatty acids (SCFAs) yield and phosphorous dissolution rate was found under the condition of pH 10.0. In pH10 + 50 g/kg-TS, the maximum concentration of SCFAs was 5591 mg-COD/L, which yield was 22.6 times higher than that of the neutral pH + 50 g/kg-TS (237 mg COD/L). The acidogenic fermentation period could be shortened to 5 days and acetic acid accounted for 70 % of SCFAs. Furthermore, PO43--P in the hydrolysate (346.5 mg/L) accounted for 47.59 % of TP, which is easier to be recovered by chemical precipitation. Therefore, a more economical and feasible utilization mode of potassium ferrate was proposed.

Isolation, structure elucidation, tyrosinase inhibitory, and antioxidant evaluation of the constituents from Angelica dahurica roots.

Two undescribed phenolic compounds, angelicols A (1) and B (2) and one undescribed coumarin rhamnoside, angelicoside A (3), together with 17 known compounds (4-20) were isolated from the roots of Angelica dahurica. Their structures were characterized by physical data analyses such as NMR, HRESIMS, and X-ray diffraction. Compounds 2, 3, 5, 6 and L-ascorbic acid (positive control) exhibited obvious DPPH radical scavenging activities with IC50 values of 0.36 mM, 0.43 mM, 0.39 mM, 0.44 mM, 0.25 mM, respectively. At a concentration of 25 µM, all compounds showed weaker tyrosinase inhibition activities (%inhibition < 5%) than kojic acid (26.00 ± 0.67%, IC50 = 44.29 ± 0.06 µM).