Synergistic removal of copper and tetracycline from aqueous solution by steam-activated bamboo-derived biochar.

Steam-activated biochar (SBC) was prepared and showed excellent performance for synergistic removal of Cu2+ and tetracycline (TC). The adsorption capacity of SBC and mutual effect of TC and Cu2+ were investigated via single and binary system and the adsorption isotherm. The adsorption capacity of TC was significantly enhanced when it coexisted with Cu2+. Likewise, increased amounts of Cu2+ were adsorbed in the presence of TC. The presence of NaCl exerted a negative influence on the adsorption of Cu2+, while the inhibitory effect of salinity on TC was neutralized by bridge enhancement in the binary system. Bridge enhancement and site competition were involved in the synergistic removal of TC and Cu2+. Considering the stable application in simulated and real water samples, SBC showed great potential for synergistic removal of antibiotics and heavy metals.

Insights into the effect of chemical treatment on the physicochemical characteristics and adsorption behavior of pig manure-derived biochars.

Chemical treatment could improve the adsorption performance of biochars (BC). In order to deal with Pb(II) pollution, four types of biochars including unmodified, acid-treated, alkali-treated, and magnetic-treated pig manure-derived biochars (PBCs) were prepared. The effect of chemical treatment on the physical property, chemical composition, and the adsorption behavior of biochars was compared. Magnetic and alkali treatment improved pore volume and specific surface areas, and the adsorption capacity and rates were enhanced. In contrast, the adsorption capacity of acid-treated BC decreased due to the significant decrease of ash content. The magnetic samples displayed the satisfactory absorption performance, which could achieve 99.8% removal efficiency within 15 min at a Pb(II) concentration of 50 mg/L. Considering its properties of excellent adsorption performance, fast reaction rate, and convenient recovery by an external magnetic field, magnetic biochar based on pig manure may provide an effective way to remove heavy metals and decrease the pig manure solid waste.

Investigating the adsorption behavior and the relative distribution of Cd2+ sorption mechanisms on biochars by different feedstock.

The objective of this study was to investigate the adsorption behavior and the relative distribution of Cd2+ sorption mechanisms on biochars by different feedstock. Bamboo biochars (BBCs), corn straw biochars (CBCs) and pig manure biochars (PBCs) were prepared at 300-700 °C. Adsorption results showed PBCs have the best adsorption capacity for Cd2+, the extra adsorption capacity of PBCs mainly attributed to the precipitation or cation exchange, which played an important role in the removal of Cd2+ by PBCs. The contribution of involved Cd2+ removal mechanism varied with feedstock due to the different components and oxygen-containing functional groups. Cd2+-π interaction was the predominant mechanism for Cd2+ removal on biochars and the contribution proportion significantly decreased from 82.17% to 61.83% as the ash content increased from 9.40% to 58.08%. Results from this study may suggest that the application of PBC is a feasible strategy for removing metal contaminants from aqueous solutions.

Application of molecularly imprinted polymers in wastewater treatment: a review.

Molecularly imprinted polymers are synthetic polymers possessing specific cavities designed for target molecules. They are prepared by copolymerization of a cross-linking agent with the complex formed from a template and monomers that have functional groups specifically interacting with the template through covalent or noncovalent bonds. Subsequent removal of the imprint template leaves specific cavities whose shape, size, and functional groups are complementary to the template molecule. Because of their predetermined selectivity, molecularly imprinted polymers (MIPs) can be used as ideal materials in wastewater treatment. Especially, MIP-based composites offer a wide range of potentialities in wastewater treatment. This paper reviews the latest applications of MIPs in wastewater treatment, highlights the development of MIP-based composites in wastewater, and offers suggestions for future success in the field of MIPs.

Synthesis of gold-cellobiose nanocomposites for colorimetric measurement of cellobiase activity.

Gold-cellobiose nanocomposites (GCNCs) were synthesized by reducing gold salt with a polysaccharide, cellobiose. Here, cellobiose acted as a controller of nucleation or stabilizer in the formation of gold nanoparticles. The obtained GCNCs were characterized with UV-visible spectroscopy; Zetasizer and Fourier transform infrared (FT-IR) spectrophotometer. Moreover, 6-Mercapto-1-hexanol (MCH) was modified on GCNCs, and the MCH-GCNCs were used to determine the cellobiase activity in compost extracts based on the surface plasmon resonance (SPR) property of MCH-GCNCs. The degradation of cellobiose on MCH-GCNCs by cellobiase could induce the aggregation, and the SPR absorption wavelength of MCH-GCNCs correspondingly red shifted. Thus, the absorbance ratio of treated MCH-GCNCs (A650/A520) could be used to estimate the cellobiase activity, and the probe exhibited highly sensitive and selective detection of the cellobiase activity with a wide linear from 3.0 to 100.0U L(-1) within 20 min. Meanwhile, a good linear relationship with correlation coefficient of R2=0.9976 was obtained. This approach successfully showed the suitability of gold nanocomposites as a colorimetric sensor for the sensitive and specific enzyme activity detection.

[Biodegradation of lignocellulose by Penicillium simplicissimum and characters of lignocellulolytic enzymes].

Penicillium simplicissimum(Oudem.) Thomrn BGA can secrete lignocellulolytic enzymes, among these enzymes the highest activities of hemicellulase, cellulase, lignin peroxidase (Lip), manganese peroxidase (Mnp) and laccase are 146.82 Iu.g-1, 2.78 U.g-1, 47.97 U.g-1, 34.56 U.g-1 and 17.94 U.g-1 respectively. According to the results and the statistical analysis of SPSS, the ability of secreting lignocellulolytic enzymes by Penicillium simplicissimum significantly correlated with the structure of lignocellulose, and the biodegradation of lignocellulose was probably a kind of synergistic effect of several lignocellulolytic enzymes. In the solid-state fermentation of 30 days, the hemicellulose content has a significantly negative correlation with the fermentation days(r = -0.946, P < 0.01), there was also a significantly negative correlation between the cellulose-biodegradation and the lignin-biodegradation (r = -0.818, P<0.05). As unselected enzymes, Lip and Mnp can degrade hemicellulose and cellulose corporately when biodegrades lignin. The significant correlation is showed between Lip, Mnp and cellulose (correlation parameters are r = 0. 922, P <0.01; r = 0.807, P<0.05 respectively). In addition, the biosorption is found to have a very important effect in the removal of liquid alkali lignin by Penicillium simplicissimum. Key words:Penicillium simplicissimum; lignocellulolytic enzymes; biodegradation; biosorption; synergistic effect

Use of iron oxide nanomaterials in wastewater treatment: a review.

Nowadays there is a continuously increasing worldwide concern for the development of wastewater treatment technologies. The utilization of iron oxide nanomaterials has received much attention due to their unique properties, such as extremely small size, high surface-area-to-volume ratio, surface modifiability, excellent magnetic properties and great biocompatibility. A range of environmental clean-up technologies have been proposed in wastewater treatment which applied iron oxide nanomaterials as nanosorbents and photocatalysts. Moreover, iron oxide based immobilization technology for enhanced removal efficiency tends to be an innovative research point. This review outlined the latest applications of iron oxide nanomaterials in wastewater treatment, and gaps which limited their large-scale field applications. The outlook for potential applications and further challenges, as well as the likely fate of nanomaterials discharged to the environment were discussed.

Oxalate production at different initial Pb²+ concentrations and the influence of oxalate during solid-state fermentation of straw with Phanerochaete chrysosporium.

The production of oxalate at different initial Pb(2+) concentrations during solid-state fermentation of straw with Phanerochaete chrysosporium was investigated. It was found that the maximal peak value of oxalate concentration (22.84 mM) was detected at the initial Pb(2+) concentration of 200 mg kg(-1) dry straw, while the minimum (15.89 mM) at the concentration of 600 mg Pb(2+)kg(-1) dry straw, and at moderate concentration of Pb(2+) the capability of oxalic acid secretion was enhanced. In addition, it was also found that more oxalic acid accumulation went together with better Pb(2+) passivation effect and higher manganese peroxidase (MnP) activity. The present findings will improve the understandings of the interactions of heavy metals with white-rot fungi and the role of oxalate in lignin degradation system, which could provide useful references for more efficient treatment of Pb-contaminated lignocellulosic waste.

Mycelial growth and solid-state fermentation of lignocellulosic waste by white-rot fungus Phanerochaete chrysosporium under lead stress.

Lignocellulosic biomass is an abundant renewable resource difficult to degrade. Its bioconversion plays important roles in carbon cycles in nature, which may be influenced by heavy metals in environment. Mycelial growth and the degradation of lignocellulosic waste by lignin-degrading fungus Phanerochaete chrysosporium under lead stress were studied. It was shown that P. chrysosporium could grow in liquid media with 400 mg L⁻¹ Pb(II), and mycelial dry weight was reduced by 54% compared to the control. Yellow mycelia in irregular short-strip shape formed in Pb-containing media, whereas the control showed ivory-white regular mycelial pellets. Two possible responses to Pb stress were: dense hyphae, and secretion from mycelia to resist Pb. During solid-state fermentation of straw, fungal colonization capability under Pb stress was positively correlated with the removal efficiency of soluble-exchangeable Pb when its content was higher than 8.2 mg kg⁻¹ dry mass. Carboxymethyl cellulase activity and cellulose degradation were inhibited at different Pb concentrations, whereas low Pb concentrations increased xylanase and ligninolytic enzyme activities and the hemicellulose and lignin degradation. Cluster analyses indicated that Pb had similar effects on the different microbial indexes related to lignin and hemicellulose degradation. The present findings will advance the understandings of lignocellulose degradation by fungi under Pb pollution, which could provide useful references for developing metal-polluted waste biotreatment technology.

[Research on sorption and transport characteristics of ligninolytic enzymes in different compost substances].

To understand the characteristics of ligninolytic enzymes sorption and transport in different compost substances, ligninolytic enzymes adsorption on soil, vegetable leaf, rice straw and chaff was comparatively studied through batch jar tests and relevant kinetics and isotherm equilibrium were discussed as well as a column experiment was performed to study the process of transport. The results showed that the sorption efficiency was depended on the sorts of substances. The adsorptive capacities of soil, vegetable leaf, rice straw and chaff to lignin peroxidase (LiP) were 1.22 U x g(-1), 1.27 U x g(-1), 1.13 U x g(-1), 1.22 U x g(-1) and to manganese peroxidase (MnP) were 5.09 U x g(-1), 4.88 U x g(-1), 4.43 U x g(-1), 3.95 U x g(-1), respectively. Comparing the kinetic models of LiP and MnP adsorption, the pseudo-second-order reaction model (R2 0.973-0.999 7) was the best of the models. Elovich equation was a bit better than pseudo-first-order kinetic which was the worst. The equilibrium data could be fitted well with Langmuir model while it could not satisfied with Freundlich model. The adsorptive saturation of soil, vegetable leaf, rice straw and chaff to LiP were 1.23 U x g(-1), 1.30 U x g(-1), 1.17 U x g(-1), 1.14 U x g(-1) and to MnP were 5.70 U x g(-1), 5.19 U x g(-1), 4.73 U x g(-1), 4.14 U x g(-1). LiP and MnP had good transport capability in straw and chaff to move to the deepest layer of 10 mL while remained in the superficial layers in soil and vegetable leaf.

Changes of microbial population structure related to lignin degradation during lignocellulosic waste composting.

Microbial populations and their relationship to bioconversion during lignocellulosic waste composting were studied by quinone profiling. Nine quinones were observed in the initial composting materials, and 15 quinones were found in compost after 50days of composting. The quinone species Q-9(H2), Q-10 and Q-10(H2) which are indicative of certain fungi appeared at the thermophilic stage but disappeared at the cooling stage. Q-10, indicative of certain fungi, and MK-7, characteristic of certain bacteria, were the predominant quinones during the thermophilic stage and were correlated with lignin degradation at the thermophilic stage. The highest lignin degradation ratio (26%) and good cellulose degradation were found at the cooling stage and were correlated with quinones Q-9, MK-7 and long-chain menaquinones attributed to mesophilic fungi, bacteria and actinomycetes, respectively. The present findings will improve the understandings of microbial dynamics and roles in composting, which could provide useful references for development of composting technology.

Biodelignification of rice straw by Phanerochaete chrysosporium in the presence of dirhamnolipid.

Lignin degradation by white-rot fungi has received considerable attention as a means for reducing accumulation of lignocellulosic wastes in the environment. The stimulatory effect of surfactants on fungal lignocellulose bioconversion also has attracted wide interest. In this study the influence of dirhamnolipid biosurfactant on biodegradation of rice straw by Phanerochaete chrysosporium was investigated. It was shown that the biodelignification process of rice straw can be significantly enhanced by the presence of dirhamnolipid biosurfactant. In particular, the dirhamnolipid at the concentration of 0.007% increased the peak activity of lignin peroxidase (LiP) by 86% without affecting the manganese peroxidase (MnP) activity. The water-soluble organic carbon (WSOC) contents in the straw substrates as well as the microbial growth and activity were effectively improved by dirhamnolipid, while the degradation rate of lignin increased by 54% with dirhamnolipid of 0.007%. Observed chemical structural and morphological changes showed that the straw substrates were delignified in the presence of dirhamnolipid with the formation of terrace-like fragments separated from the inner cellular fibers and the release of simple compounds. Variation partitioning analysis revealed that the dirhamnolipid addition induced a significant straw biodelignification which explained 22.1% (P = 0.013) of the variance.

[Analysis of the effect of enzymes on microbial community metabolic profiles during composting using biolog method].

The effects of enzymes on organic material degradation and microbial communities metabolic profiles during composting process were studied using Biolog method, and together with cluster analysis and PCA. The results showed that, adding the enzyme solution in the composting could increase the degradation rate of organic material by 4.90%. The microbial community metabolic results of cluster analysis showed that when the enzyme solution was added into the compost, the carbon metabolic capability of intermediate metabolite was improved. The results of PCA indicated that when the enzyme solution was added, microbial communities enhanced the metabolic capability of miscellaneous, polymers, amino acids and amides carbon substrates, which results in the efficient degradation of organic substance. In addition, cluster analysis of each composting phase showed that the effects of the enzymes solution on microbial community metabolism were mainly observed on 6 d and 30 d, which promoted the composting process.

Adsorption of lead(II) from aqueous solution onto Hydrilla verticillata.

The adsorption of Pb(II) onto Hydrilla verticillata was examined in aqueous solution with parameters of pH, adsorbent dosage, contact time and temperature. The linear Langmuir and Freundlich models were applied to describe equilibrium isotherms, and both models fitted well. The monolayer adsorption capacity of Pb(II) was found as 104.2 mg/g at pH 4 and 25 degrees C. Dubinin-Radushkevich (D-R) isotherm model was also applied to the equilibrium data. The mean free energy of adsorption (15.81 kJ/mol) indicated that the adsorption of Pb(II) onto H. verticillata may be carried out via chemical ion-exchange mechanism. Thermodynamic parameters, free energy (DeltaG (0)), enthalpy (DeltaH (0)) and entropy (DeltaS (0)) of adsorption were also calculated. These parameters showed that the adsorption of Pb(II) onto H. verticillata was a feasible, spontaneous and exothermic process in nature. The influence of Cd(2+), Cu(2+) and Ni(2+) on adsorption of Pb(2+) onto H. verticillata was studied, too. In the investigated range of operating conditions, it was found that the existence of Cd (2+), Cu (2+) and Ni (2+) had no impact on the adsorption of Pb(2+).

Degradation of lead-contaminated lignocellulosic waste by Phanerochaete chrysosporium and the reduction of lead toxicity.

Lead, as one of the most hazardous heavy metals to the environment interferes with lignocellulosic biomass bioconversion and carbon cycles in nature. The degradation of lead-polluted lignocellulosic waste and the restrain of lead hazards by solid-state fermentation with Phanerochaete chrysosporium were studied. Phanerochaete chrysosporium effectively degraded lignocellulose, formed humus and reduced active lead ions, even at the concentration of 400 mg/kg dry mass of lead. The highest lignocellulose degradation (56.8%) and organic matter loss (64.0%) were found at the concentration of 30 mg/kg of lead, and at low concentration of lead the capability of selective lignin biodegradation was enhanced. Microbial growth was delayed in polluted substrate at the initial stage of fermentation, and organic matter loss is correlated positively with microbial biomass after 12 day fermentation. It might be because Phanerochaete chrysosporium developed active defense mechanism to alleviate the lead toxicity. Scanning electron micrographs with energy spectra showed that lead was immobilized via two possible routes: adsorption and cation exchange on hypha, and the chelation by fungal metabolite. The present findings will improve the understandings about the degradation process and the lead immobilization pathway, which could be used as references for developing a fungi-based treatment technology for metal-contaminated lignocellulosic waste.

Rapid detection of picloram in agricultural field samples using a disposable immunomembrane-based electrochemical sensor.

Picloram, a widely used chlorinated herbicide, is quite persistent and mobile in soil and water with adverse health and environmental effects. It is essential to establish a rapid and sensitive method for accurate detection of trace picloram in agricultural samples. We employed a disposable, nontoxic, and conductive chitosan/gold nanoparticles composite membrane on electrochemical sensor for the sensitive detection of picloram in several agricultural field samples. A self-synthesized picloram antibody was encapsulated in the immunomembrane to form an immunoconjugate by a competitive immunoreaction in sample solution, followed by the immobilization of horseradish peroxidase (HRP)-labeled secondary antibody. The immunomembrane possessed good reproducibility for fabrication in batch, providing a congenial microenvironment for the immune molecules. The diffused colloidal Au nanoparticles shuttled the electron transfer between the immobilized HRP and the electrode surface. To demonstrate the suitability of the immunosensor for on-site detection, rice, lettuce, and paddy field water were spiked with picloram and assayed without preconcentration. Under optimal conditions, picloram could be detected in the range from 0.005 to 10 microg/mL with the correlation coefficient of 0.9937, and the detection limit is 5 ng/ mL. The proposed immunosensor exhibited good precision, sensitivity, selectivity, and storage stability.

A hydroquinone biosensor using modified core-shell magnetic nanoparticles supported on carbon paste electrode.

A hydroquinone biosensor was developed and used to determine hydroquinone concentration in compost extracts based on the immobilization of laccase on the surface of modified magnetic core-shell (Fe(3)O(4)-SiO2) nanoparticles. Laccase was covalently immobilized on the magnetic nanoparticles by glutaraldehyde, which was modified with amino groups on its surface. The obtained magnetic bio-nanoparticles were attached to the surface of carbon paste electrode with the aid of a permanent magnet to determine hydroquinone. A good microenvironment for retaining the bioactivity of laccase was provided by the immobilization matrix. The linear range for hydroquinone determination was 1 x 10(-7) to 1.375 x 10(-4)M, with a detection limit of 1.5 x 10(-8)M. The current reached 95% of the steady-state current within about 60s. Hydroquinone concentration in compost extracts was determined by laccase biosensor and HPLC, the results of the two methods were approximately the same.

Use of potassium dihydrogen phosphate and sawdust as adsorbents of ammoniacal nitrogen in aerobic composting process.

Three kinds of adsorbents-potassium dihydrogen phosphate, sawdust and mixture of potassium dihydrogen phosphate and sawdust were added respectively into composting to investigate their adsorption effect on ammonia. The experimental results showed that all the adsorbents could restrain ammonia volatilizing, with the sorption of potassium dihydrogen phosphate adsorbents being the best of all, the sorption of mixture adsorbent with potassium dihydrogen phosphate and sawdust being the second and the sorption of sawdust adsorbent being the last. Therefore, the total nitrogen loss ratios respectively reduced from 38% to 13%, 15% and 21% after adding these three kinds of adsorbents into composting. However, potassium dihydrogen phosphate produced negative influence on composting properties as its supplemented amount exceeded a quantity basis equivalent to 18% of total nitrogen in the composting, for example: pH value had been lessened, microorganism activity reduced, which finally resulted in the reduction of biodegradation ratio of organic matter. But it did not result in these problems when using the mixture of potassium dihydrogen phosphate and sawdust as adsorbent, in which the amount of potassium dihydrogen phosphate was under a quantity basis equivalent to 6% of total nitrogen in the composting. Moreover, the mixture adsorbent produced better adsorption effect on ammonia, and raised biodegradation ratio of organic matter from 26% to 33%.

[Microbial community changes during the degradation of straw using phospholipid fatty acid analysis].

Solid-state fermentation system of rice straw was established with the inoculation of soil microorganism and Phanerochaete chrysosporium. Microbial biomass and community structure were investigated using the phospholipid fatty acid (PLFA) technique, and the changes of lignocellulose's degradation rate were also detected during the process. The experimental results show that lignocellulose degradation rate reaches 44% after fermentation. When the total amount of phospholipid fatty acid is separated into indicator phospholipid fatty acids for different groups of microorganisms, these groups show different patterns during the process. Contents of PLFA in gram-positive bacteria, gram-negative and fungi reach their peak value on the sixth day. Gram-positive bacteria have lower contents. The PLFA content ratio of fungi and bacteria is 0.2 - 0.5, so fungi are the main community decomposing lignocellulose. Principal component analysis of the PLFA data show that 18 carbon unsaturated fatty acids are the major fatty acids at the end of the process, which is consistent with the results of indicator phospholipid fatty acids and lignocellulose's degradation rates, so PLFA technique is able to fairly well detect the changes of microbial biomass and community structure in solid-state fermentation system of rice straw.

[Application of white-rot fungi in composting lead-contaminated waste].

Simulative lead polluted wastes which containing unpolluted soil, household waste, straw, bran and lead nitrate were prepared. Inoculation of white-rot fungi and uninoculation in composting of lead-contaminated waste were studied. Change of chemical factor, biological parameter and biological toxicity analyses with time during the composting process were determined to study effect of heavy metal on composting process and probability of application of white-rot fungi in composting of metal-contaminated waste. The results show the composting of lead-contaminated waste inoculated white-rot fungi could be successfully processed, which lead to the reduction of the bioavailability of Pb in compost and alleviate the potential harm from heavy metal. Under this composting process, for the final compost, pH, water-soluble organic carbon/nitrogen, volatile solid, lignin and coarse fibre remained reached 7.9, 4.01, 36.1%, 22.4g, 30.1g, respectively. In addition, 63.38% of Pb in residual fraction and 0% of Pb in soluble-exchangeable fraction were found in final compost, and the germination index of final compost reached 121%.