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The key factors (initial pH value, substrate concentration, incubation time, C/N and L-cysteine concentration) that affect biohydrogen production from microcrystalline cellulose in batch fermentation by the co-culture of isolated strains (Clostridium acetobutylicum X9 + Ethanoigenens harbinense B2) were optimized using an orthogonal experiment. The isolated strain, Clostridium acetobutylicum X9, had high hydrogen yield from microcrystalline cellulose (MCC), and Ethanoigenens harbinense B2 could produce hydrogen efficiently from monosaccharides directly from microcrystalline cellulose. The optimal parameters were as follows: initial pH value of 6.0, 12 g L−1 substrate concentration, 40 h incubation time, 0.7 g L−1 L-cysteine concentration and a 4 : 1 ratio of C/N. Under the optimum culture conditions, a maximum hydrogen yield rate of 10.4 mmol g-MCC−1 was obtained. This yield is approximately 2.2-fold greater than that of mono-culture Clostridium acetobutylicum X9. It suggests that the optimal conditions achieved can be applied to the production of hydrogen from microcrystalline cellulose using the co-culture of isolated strains, Clostridium acetobutylicum X9 + Ethanoigenens harbinense B2.

In order to enhance the productivity of methane from the waste activated sludge (WAS), a coupled system of microbial electrolysis cell (MEC) and anaerobic digestion (AD) was proposed. In this study, alkali, ultrasound-alkali, high-temperature coupled microaeration (TM) were applied as pretreatment methods to disintegrate the WAS flocs and break bacterial cell. After ultrasound-alkali pretreatment, the maximum accumulated concentration of VFAs and SCOD increased by 6.4 and 13.8 times compared with the initial concentration, which were 2.8 and 2.6 times of alkali pretreatment, and 2.1 and 2.1 times of TM pretreatment. Then, the pretreated sludge was transferred into MEC-AD coupled reactors and control group of AD reactors. The results showed that, methane production rate was enhanced to 0.15 m3 CH4/m3 reactor/d in the coupled reactors, which was improved by 3 times compared with control AD (0.05 m3 CH4/m3 reactor/d). The methane yield of MEC-AD coupled reactors achieved 808 ± 8 mL, which were increased by 97.0% ± 1.85% compared to control AD (410 mL). Using MEC can promote the rate of organics degradation and methane yield. The MEC-AD coupled system realized a good performance on the treatment of WAS and improved the efficiency of methane production.

Large quantities of deicing salts are applied in urban areas for clearing the pavement and ensuring the normal traffic flow during the winter seasons in northeastern China.The salt from deicing operation has been observed to accumulate in roadside soil and inhibit the growth of vegetation.It was reported that the application of exogenous K+ and salicylic acid(SA) could protect plants against abiotic stress.In this study,pot experiments were performed in soil culture to test the efficacy of two soil additives,potassium nitrate(KNO3) and SA,in alleviating the stress of deicing salts on growth and photosynthetic parameters of Pinus tabulaeformis seedlings.Three soil additive levels were used i.e.10,20,40 mmol/L for KNO3 and 2,4,8 mmol/L for SA,respectively,under the stress of 0.2% deicing salts per dry weight of soil.After the treatment for 20 days(d),relative water content,leakage rates of electrolyte,malondialdehyde(MDA),peroxidase(POD) and chlorophyll content in leaves were determined.Dry weight of roots,stems and leaves were measured respectively after 60 d of treatments.Three important parameters of photosynthesis,photosynthetic rates(Pn),intracellular CO2 concentrations(Ci) and stomatal conductance(Gs) were measured every 7 d until 35 d. The results showed that the growth of seedlings was inhibited significantly by the stress of 0.2% deicing salts.The dry weight and relative water content of roots,stems and leaves under 0.2% deicing salt stress were decreased significantly in comparison with the control seedlings.The leaves of Pinus tabulaeformis were more sensitive to the stress of deicing salts compared with roots and stems.However,the treatment of 20 mmol/L KNO3 and 2mmol/L SA to 0.2% deicing salts had high dry weight and water content.Meanwhile,the MDA content and leakage rates of electrolyte increased once exposure to 0.2% deicing salts,and salts exposure also had an inhibitory effect on the activities of the POD.However,with the addition of 20 mmol/L KNO3 and 2 mmol/L SA,the high stability of membrane was improved by promoting the POD activities,with decreasing plasmalemma permeability and MDA content in leaves.On the other hand,the contents of Pn,Ci,Gs and the chlorophyll all decreased in the Pinus tabulaeformis seedlings by the treatment of 0.2% deicing salts.The addition of 20 mmol/L KNO3 significantly increased photosynthetic rates from 5.77% to 20.6% with the prolonging of the exposure time.However,other treatments were found no obvious alleviation effect.It was also found that the contents of Ci and Gs remained unchanged in leaves of Pinus tabulaeformis seedlings in all alleviation treatments,but the enhancing of chlorophyll contents played a key role in maintaining the leaf photosynthetic rate under the treatment of KNO3 and SA.The results indicated that the salt tolerance of Pinus tabulaeformis seedlings was improved by using soil additives of 20 mmol/L KNO3 and 2 mmol/L SA.Exogenous K+ and SA showed strong benefits against deicing salts-induced negative symptoms.

Due to the problems of the hydrolysis of wasted activated sludge (WAS), fermentation stage takes a long time and volatile fatty acids (VFAs) output efficiency is low. This study investigated the effect of ultrasound combined with Fenton (US/Fenton) pretreatment on the sludge disintegration and anaerobic fermentation. The sludge was treated by three different pretreatments respectively: ultrasound alone, Fenton alone and US/Fenton. Results show that after three pretreatments, sludge floc structure was disintegrated and oxidized, the sludge particle morphology after US/Fenton pretreatment was changed the most obviously. After US/Fenton, specific surface area was the largest and the particle size reduction was remarkable from 50.24 μm to22.44 μm. The SCOD concentration after US/Fenton was 3461.72 mg COD L-1, which was raised 1.73 times, 2.68 times and13.29 times as against that after ultrasound, Fenton and the untreated. The degree of disintegration (DDCOD) of the US/Fenton pretreatment was 15.4% which was greater than ultrasound pretreatment of 9.97% and Fenton pretreatment of 3.18%. The VFAs concentration after US/Fenton pretreatment reached a maximum value of 4594 mg COD L-1 at the eighth day, it was raised 31.8% and 70.15% as separately compared with the Fenton and ultrasound pretreatments. The pretreatments changed the VFAs composition and proportion. The highest HAC concentration after US/Fenton was 2039 mg COD L-1, which was 1.72 and 1.78 times of that in Fenton and ultrasound, respectively. This study showed that the US/Fenton pretreatment had a certain synergistic promotion effect on the sludge anaerobic fermentation. The ultrasound and Fenton co-work, the ability of the VFAs production is further improved.

Although RuO2-TiO2 anodes (DSAs) have been widely used in electrochemical technology since the late 1960s, and the work to find the mechanism of its activity loss has been extensive, the published papers contain very few descriptions relating to the degradation caused in the brine electrolyte. The aim of the present work is to investigate the mechanism of the activity loss of the DSA in a saturated NaCl solution whilst operating at a high current density. It is obvious that the results obtained here will match closely the conditions existing in the chlor-alkali industry, which is the most significant application of DSAs. During anodic polarization a detailed investigation, especially of the variations in composition and structure of the oxide layer, was carried out in terms of the electrochemical and physical surface methods until the end of the service life of the anode. Based on the data obtained, the reasons for the degradation of RuO2-TiO2 anodes in NaCl aqueous solutions are discussed.