Biodegradation of 2-naphthol and its metabolites by coupling Aspergillus niger with Bacillus subtilis

To explore biodegradation of 2-naphthol and its metabolites accumulated in wastewater treatment,a series of bio-degradation experiments were conducted.Two main metabolites of 2-naphthol,1,2-naphthalene-diol and 1,2-naphthoquinone,were identified by high-performance liquid chromatography with standards.Combining fungus Aspergillus niger with bacterium Bacillus subtilis in the treatment enhanced 2-naphthol degradation efficiency,lowered the accumulation of the two toxic metabolites.There were two main phases during the degradation process by the kinetic analysis：2-naphthol was first partly degraded by the fungus,producing labile and easily accumulated metabolites,and then the metabolites were mainly degraded by the bacterium,attested by the degradation processes of 1,2-naphthalene-diol and 1,2-naphthoquinone as sole source of carbon and energy.Sodium succinate,as a co-metabolic substrate,was the most suitable compound for the continuous degradation.The optimum concentration of 2-naphthol was 50 mg/L.The overall 2-naphthol degradation rate was 92%,and the COD Cr removal rate was 80% on day 10.These results indicated that high degradation rate of 2-naphthol should not be considered as the sole desirable criterion for the bioremediation of 2-naphtholcontaminated soils/wastewater.

Adsorption removal of roxarsone, arsenite(Ⅲ),and arsenate(Ⅴ) using iron-modified sorghum straw biochar and its kinetics

Arsenic(As)contamination in groundwater is a major problem in many countries,which causes serious health issues.In this paper,a novel method has been developed for the simultaneous removal of ROX and As(Ⅲ/Ⅴ)using the modified sorghum straw biochar(MSSB).The MSSB was characterized by X-ray diffraction,scanning electron microscopy,Fourier Transform Infrared,and Brunauer–Emmet–Teller(BET)surface area.The removal performance of MSSB for ROX,arsenite[As(Ⅲ)],and arsenate(As(Ⅴ))was investigated using batch experiments.At pH of 5,the arsenic concentration of 1.0 mg/L,adsorbent dose of 1.0 g/L,the maximum adsorptioncapacities of ROX,As(Ⅲ),and As(Ⅴ)were 12.4,5.3,and 23.0 mg/g,respectively.The adsorption behaviors were fit well with the Langmuir and the pseudo-second-order rate model.The results showed that MSSB acted as a highly effective adsorbent to simultaneously remove the composite pollution system consisted of ROX and As(Ⅲ/Ⅴ)in aqueous solutions,providing a promising method in environmental restoration applications.