Junyuan Guo

Removal of triazophos pesticide from wastewater with Fenton reagent

The catalytic oxidation of triazophos pesticide from wastewater using Fenton reagent was investigated at bench-scale in this study. Synthesized wastewater and actual industrial triazophos pesticide wastewater taken from a pesticide company were examined sequentially. The COD values of the synthesized and actual industrial triazophos pesticide wastewater samples were 3242 and 3418 mg/L, respectively, and the triazophos concentration in these wastewater samples was 0.06% by weight. The effects of reaction conditions including the dosages of FeSO(4).7H(2)O and H(2)O(2), the pH value of the environment, and the stirring time on COD removal from the synthesized wastewater were evaluated, and COD removal efficiency of 96.3% with a corresponding effluent COD value of 120 mg/L was achieved under optimal reaction conditions of a pH value of 4, a dosage of 2.5 g/L of FeSO(4).7H(2)O and 100 mL/L of 30% H(2)O(2) solution, and a stirring time of 90 min. Results also showed that 71.2% of nitrogen and 68.5% of phosphorous in the synthesized triazophos wastewater were converted to NO(3)(-) and PO(4)(3-), respectively, at the optimal reaction condition. When the actual industrial wastewater was treated at a pH value of 4, COD removal efficiency of 85.4% with a corresponding effluent COD value of 499 mg/L were reached at optimal condition of a dosage of 5.0 g/L of FeSO(4).7H(2)O and 75 mL/L of 30% H(2)O(2) solution, and a stirring time of 90 min. The results of this study can be referred for the design of a treatment process for the actual industrial triazophos wastewater.

Treatment of swine wastewater using chemically modified zeolite and bioflocculant from activated sludge.

Sterilization, alkaline-thermal and acid-thermal treatments were applied to activated sludge and the pre-treated sludge was used as raw material for Rhodococcus R3 to produce polymeric substances. After 60 h of fermentation, bioflocculant of 2.7 and 4.2 g L(-1) were produced in sterilized and alkaline-thermal treated sludge as compared to that of 0.9 g L(-1) in acid-thermal treated sludge. Response surface methodology (RSM) was employed to optimize the treatment process of swine wastewater using the composite of bioflocculant and zeolite modified by calcining with MgO. The optimal flocculating conditions were bioflocculant of 24 mg L(-1), modified zeolite of 12 g L(-1), CaCl2 of 16 mg L(-1), pH of 8.3 and contact time of 55 min, and the corresponding removal rates of COD, ammonium and turbidity were 87.9%, 86.9%, and 94.8%. The use of the composite by RSM provides a feasible way to improve the pollutant removal efficiencies and recycle high-level of ammonium from wastewater.

Preparation and characteristics of bacterial polymer using pre-treated sludge from swine wastewater treatment plant.

Sterilization, alkaline-thermal, and acid-thermal treatments were applied to different suspended sludge solids (SSS) concentrations and the pre-treated sludge was used as raw material for bioflocculant-producing bacteria R3 to produce bioflocculant. After 60 h of fermentation, three forms of bioflocculant (broth, capsular, and slime) were extracted, and maximum broth bioflocculant of 2.9 and 4.1 g L(-1) were produced in sterilized and alkaline-thermal treated sludge as compared to that of 1.8 g L(-1) in acid-thermal treated sludge. Higher bioflocculant quantity was produced in SS of 15, 25, and 35 g L(-1) compared to that produced in SS of 45, 55, and 65 g L(-1). Bioflocculant combined with 0.5 g Ca(2+) in 1.0 L kaolin suspension acted as conditioning agent, and maximum flocculating activity of 94.5% and 92.8% was achieved using broth and slime bioflocculant, respectively. The results demonstrated that wastewater sludge could be used as sources to prepare bioflocculants.

Characterization and flocculation mechanism of a bioflocculant from hydrolyzate of rice stover.

This study investigated the characterization and flocculation mechanism of a bioflocculant from hydrolyzate of rice stover. Production of the bioflocculant was positively associated with cell growth and a highest value of 2.4 g L(-1) was obtained. During the kaolin suspension flocculation, charge neutralization and inter-particle bridging were proposed as the reasons for enhanced performance. Apart from this, the bioflocculant showed good performances in sludge dewatering and swine wastewater pretreatment. After conditioning by the bioflocculant, dry solids (DS) and specific resistance to filtration (SRF) of the sludge reached 18.4% and 4.8×10(12) m kg(-1), respectively, which were much better than that by conventional chemical flocculants. In the swine wastewater pretreatment, the removal efficiencies of COD, ammonium, and turbidity reached 48.3%, 43.6% and 75.8% at pH 8.0 when the bioflocculant dose was adjusted to 20 mg L(-1).

Characterization and flocculation mechanism of a bioflocculant from potato starch wastewater

This study investigated the characterization and flocculation mechanism of a bioflocculant prepared using potato starch wastewater. The optimal culture conditions of this strain were determined as 4xa0g K2HPO4, 2xa0g KH2PO4, 0.2xa0g MgSO4, 0.1xa0g NaCl, and 2.0xa0g urea dissolved in 1.0xa0L potato starch wastewater with no need of adding carbon sources or adjusting pH value. Production of this bioflocculant was positively associated with cell growth, and a highest value of 0.81xa0g/L was obtained. During the kaolin suspension flocculation, charge neutralization and interparticle bridging were proposed as the main reasons for enhanced performance. Further, with potato starch wastewater, chemical oxygen demand (COD) and turbidity removal rates reached 52.4 and 81.7xa0%, respectively, at pHxa07.5 when the bioflocculant dose was adjusted to 30xa0mg/L.

Characteristics and mechanisms of Cu(II) sorption from aqueous solution by using bioflocculant MBFR10543

This paper investigated the characteristics of Cu(II) sorption from aqueous solution by using bioflocculant MBFR10543 and discussed the mechanism during the sorption process. Results have demonstrated that the removal efficiency of Cu(II) reached 96.9xa0% by adding MBFR10543 in two stages, separately, 1.5u2009×u200910−2xa0% (w/w) in the 1.0-min rapid mixing (180xa0rpm) and 2.0u2009×u200910−2xa0% (w/w) after 2.0-min slow mixing (80xa0rpm), with pH value fixed at 6.0. Cu(II) sorption process could be described by the pseudo-second-order kinetic model and the Langmuir isotherms model. The negative Gibbs free energy change indicated the spontaneous nature of the sorption. Fourier transform infrared spectra analysis indicated that functional groups, such as –OH, −COOH, C═O, and –NH2, were existed in MBFR10543 molecular chains, which had strong capacity for removing Cu(II). Furthermore, both charge neutralization and bridging being the main mechanisms involved in Cu(II) removal by MBFR10543.

Enhanced dewatering of sludge with the composite of bioflocculant MBFGA1 and P(AM-DMC) as a conditioner

Bioflocculant MBFGA1 was investigated to be used as a conditioner for sludge dewatering, and the response surface methodology (RSM) was employed to study the enhancing performance of the dewatering process by the composite of MBFGA1 and poly(acrylamide [2-(methacryloyloxy)ethyl]-trimethylammonium chloride) (P(AM-DMC)). Results showed that dry solids (DS) and specific resistance to filtration (SRF) of sludge treated by MBFGA1 alone appeared as 21.7xa0% and 3.6u2009×u20091012xa0mxa0kg−1, respectively, which were much better than FeCl3, Al2(SO4)3, and polyaluminum chloride (PAC), but poorer than P(AM-DMC) in sludge dewatering. Apart from this, the optimized conditioning process for improving the dewaterability of the sludge conditioned by the composite is MBFGA1 of 1.4xa0gxa0L−1, P(AM-DMC) of 0.13xa0gxa0L−1, CaCl2 of 56.1xa0mgxa0L−1, pH value of 7.5, and agitation speed of 149xa0rpm. Under this optimal condition, DS and SRF appeared as 29.9xa0% and 2.2u2009×u20091012xa0mxa0kg−1, respectively. Thus, it is feasible and meaningful to enhance the dewaterability of the sludge by the compound uses of MBFGA1 and P(AM-DMC).

Characterization of a bioflocculant from potato starch wastewater and its application in sludge dewatering.

A bioflocculant was produced by using potato starch wastewater; its potential in sludge dewatering and potato starch wastewater treatment was investigated. Production of this bioflocculant was positively associated with cell growth, and a highest value of 0.81xa0g/L was obtained. When incubated with this bioflocculant, dry solids (DS) and specific resistance to filtration (SRF) of typical wastewater activated sludge reached 20.8xa0% and 3.9u2009×u20091012xa0m/kg, respectively, which were much better than the ones obtained with conventional chemical flocculants. Sludge dewatering was further improved when both the bioflocculant and conventional polyacrylamide (PAM) were used simultaneously. With potato starch wastewater, chemical oxygen demand (COD) and turbidity removal rates could reach 52.4 and 81.7xa0%, respectively, at pH value of 7.5 when the bioflocculant dose was adjusted to 30xa0mg/L; from a practical standpoint, the removal of COD and turbidity reached 48.3 and 72.5xa0%, respectively, without pH value adjustment.

Sorption characteristics and mechanisms of Pb(II) from aqueous solution by using bioflocculant MBFR10543

This paper focuses on the effectiveness of removing Pb(II) from aqueous solution using bioflocculant MBFR10543 and a series of experimental parameters including MBFR10543 dose, calcium ions concentration, solution pH, and temperature on Pb(II) uptake was evaluated. Meanwhile, the flocculation mechanism of MBFR10543 was discussed. Results have demonstrated that the removal efficiency of Pb(II) reached 94.7xa0% (with the sorption capacity of 81.2xa0mgu2009·u2009g−1) by adding MBFR10543 in two stages, separately, 3u2009×u200910−2xa0% (w/w) in the 1.0xa0min’s rapid mixing (180xa0rpm) and 4u2009×u200910−2xa0% (w/w) after 2.0xa0min’s slow mixing (80xa0rpm) with pH value fixed at 6. Pb(II) flocculation process could be described by the Langmuir isotherms model and pseudo-second-order kinetic model. The negative Gibbs free energy change indicated the spontaneous nature of the flocculation. Fourier transform infrared spectra analysis indicated that functional groups, such as –OH, C=O, and C–N, were existed in MBFR10543 molecular chains, which had strong capacity for removing Pb(II). Furthermore, both charge neutralization and bridging being the main mechanisms involved in Pb(II) removal by MBFR10543.

Bioflocculant from pre-treated sludge and its applications in sludge dewatering and swine wastewater pretreatment.

Potentials of alkaline-thermal (ALT) pre-treated sludge as a bioflocculant were studied in sludge dewatering and swine wastewater pretreatment. When incubated with this ALT pre-treated sludge, dry solids (DS) and specific resistance to filtration (SRF) of typical wastewater activated sludge reached 22.5% and 3.4×10(12)m/kg, respectively, which were much better than that obtained with conventional chemical flocculants. Sludge dewatering was further improved when both the bioflocculant and conventional polyaluminum chloride (PAC) were used simultaneously. Charge neutralization and inter-particle bridging were proposed as the reasons for the enhanced performance in the case of the combined use. With swine wastewater, the bioflocculant could remove COD, ammonium and turbidity by 45.2%, 41.8% and 74.6% when incubated with 20mg/L at pH 8.0. This study suggested that the ALT pre-treated sludge has a great potential as an alternative bioflocculant to conventional flocculants in sludge dewatering and swine wastewater pretreatment.