Yinzhang Liao

Comparison of Seven Chemical Pretreatments of Corn Straw for Improving Methane Yield by Anaerobic Digestion

Agriculture straw is considered a renewable resource that has the potential to contribute greatly to bioenergy supplies. Chemical pretreatment prior to anaerobic digestion can increase the anaerobic digestibility of agriculture straw. The present study investigated the effects of seven chemical pretreatments on the composition and methane yield of corn straw to assess their effectiveness of digestibility. Four acid reagents (H2SO4, HCl, H2O2, and CH3COOH) at concentrations of 1%, 2%, 3%, and 4% (w/w) and three alkaline reagents (NaOH, Ca(OH)2, and NH3·H2O) at concentrations of 4%, 6%, 8%, and 10% (w/w) were used for the pretreatments. All pretreatments were effective in the biodegradation of the lignocellulosic straw structure. The straw, pretreated with 3% H2O2 and 8% Ca(OH)2, acquired the highest methane yield of 216.7 and 206.6 mL CH4 g VS −1 in the acid and alkaline pretreatments, which are 115.4% and 105.3% greater than the untreated straw. H2O2 and Ca(OH)2 can be considered as the most favorable pretreatment methods for improving the methane yield of straw because of their effectiveness and low cost.

Deodorization study of the swine manure with two yeast strains

With the transition of livestock production from the traditional small household farming to large-scale centralized breeding, the odor pollution caused by livestock manure has become pressing in China. In this study, two yeast strains Y1 and Y2 with high deodorization efficiency were isolated from the sample collected from an outlet in a swine farm in Shuangliu County, Sichuan Province. The scale-up deodorization experiments were carried out for strains Y1, Y2, and their mixture Y1+Y2. The results showed that the reduction rate of treatments on NH3 was in the sequence of Y1+Y2 (35.6 ∼ 68.7%) >Y1 (20.3 ∼ 63.7%) >Y2 (−11.7 ∼ 53.8%). The reduction rate of treatments on H2S was in the sequence of Y1+Y2 (47.2 ∼ 70.1%) > Y2 (36.6 ∼ 60.8%) > Y1 (27.6 ∼ 42.0%). The reduction rate of treatments on total volatile organic compounds (TVOC) was in the sequence of Y1+Y2 (49.1 ∼ 68.3%) > Y1 (36.2 ∼ 54.6%) >Y2 (20.8 ∼ 48.6%). The reduction rate of treatments on odor intensity was in the sequence of Y1+Y2 (27.2–60.3%) > Y1 (16.3 ∼ 38.5%) >Y2 (−0.4 ∼ 35.2%). Furthermore, the concentrations of VFAs, indole, skatole, total nitrogen (TN), organic nitrogen (ON), total sulfur (TS), and ammonium nitrogen (AN) in swine manure during deodorization by yeast strains Y1, Y2, and their mixture Y1+Y2 were assayed. The results showed the concentrations of VFAs, indole, and skatole in the manure with Y1, Y2, and Y1+Y2 treatments were all lower than those of the control group. The concentrations of TN, ON, and TS in treatments were all higher than that of the control group. The concentrations of AN in the treatment groups were all lower than those of the control group.

Isolation, Identification and Phylogenetic Analysis of an Alkalophilic Methanosarcina

An alkalophilic methanogen T13 was isolated by anaerobic techniques of Hungate from cow muck in Hongyuan county,Sichuan,China enriched in culture for methanogen at 15 ℃.Its optimum pH for producing methane was 8.5,and the temperature for growth was observed at the range of 8~45 ℃.The culture was visible particulate.Cells were aggregated and gram-positive.The colony was pale yellow,mulberry-like and fluoresced.T13 could grow using acetate,methanol or methylamine as sole carbon source,and it was sensitive to chloramphenicol and gentamicin.The optimum temperature and NaCl concentration for its growth were 30 ℃ and 0~0.15 mol L-1,respectively.It grew at the pH range between 6.5 and 9.5.The morphological and physio-biochemical characteristics combined with 16S rDNA sequence analysis of strain T13 demonstrated that it was a strain of Methanosarcina mazei.Since its optimum pH for growth was 8.5,strain T13 therefore was considered preliminarily as a new strain of M.mazei.

Screening of a Thermostable Cellulase-producing Strain and Its Enzymatic Properties

Using CMC Congo Red agar plate method,an actinomycetic strain producing cellulase with high temperature tolerance and pH stability was isolated from the sample collected from mushroom plantation.The strain was identified and named as Thermobifida fusca DY3 by morphological,physiological and biochemical characteristics,and 16S rDNA gene sequence analysis.The study on the cellulase showed that the extracellular thermostable cellualse exhibited the maximum activity at 65 ℃ and retained more than 75% of its maximum activity after incubation for 60 minutes at 70 ℃.The enzyme also showed its pH stability between pH 5.5 and 10.0,and retained 80% of its maximum enzymatic activity after treated at pH 10.0.The sodium carboxymethylcellulose was its best zymolyte.All the characteristics of the enzyme provide reference value for its application in biological pretreatment of lignocellulose.