Five New Glycoside Constituents from the Roots of Gentiana crassicaulis Duthie ex Burk.

Three undescribed glycoside constituents, macrophyllosides E-G and a pair of iridoid glycosides genticrasides A/B, together with eleven known glycoside compounds were isolated from the roots of Gentiana crassicaulis Duthie ex Burk. Their structures were identified by means of spectra analysis and data comparison with previous literatures. Interestingly, the glucose moieties in macrophylloside E and F possess free anomeric hydroxy groups. Genticrasides A/B, identified as a pair of iridoid originated lactones, have not been reported from Gentianaceae family up to now. The anti-inflammatory effects of selected compounds were also evaluated through the nitric oxide (NO) production inhibition in lipopolysaccharides (LPS)-induced RAW264.7 macrophage cells. In which, macrophyllosides G and D showed NO inhibitory activities with rates of 76.14±4.02 % and 52.44±8.29 % at 100 µg/mL.

Standardized Nursing Procedures for Fecal Microbiota Transplantation via Upper Endoscopy.

Fecal microbiota transplantation is an emerging treatment option that lacks a standardized nursing procedure. In our department, fecal microbiota transplantation has been undertaken to treat chronic hepatitis B and inflammatory bowel diseases since 2015. The fecal microbiota transplantation process involves various nursing measures that are critical for the successful completion of the procedures. In our center, a set of standardized nursing procedures has been established and has proved effective and operable. Standardized nursing procedures enhance the efficacy of fecal microbiota transplantation and alleviate the risk of treatment-related complications.

Innexin hemichannel activation by Microplitis bicoloratus ecSOD monopolymer reduces ROS.

The extracellular superoxide dismutases (ecSODs) secreted by Microplitis bicoloratus reduce the reactive oxygen species (ROS) stimulated by the Microplitis bicoloratus bracovirus. Here, we demonstrate that the bacterial transferase hexapeptide (hexapep) motif and bacterial-immunoglobulin-like (BIg-like) domain of ecSODs bind to the cell membrane and transiently open hemichannels, facilitating ROS reductions. RNAi-mediated ecSOD silencing in vivo elevated ROS in host hemocytes, impairing parasitoid larva development. In vitro, the ecSOD-monopolymer needed to be membrane bound to open hemichannels. Furthermore, the hexapep motif in the beta-sandwich of ecSOD49 and ecSOD58, and BIg-like domain in the signal peptides of ecSOD67 were required for cell membrane binding. Hexapep motif and BIg-like domain deletions induced ecSODs loss of adhesion and ROS reduction failure. The hexapep motif and BIg-like domain mediated ecSOD binding via upregulating innexins and stabilizing the opened hemichannels. Our findings reveal a mechanism through which ecSOD reduces ROS, which may aid in developing anti-redox therapy.

Simulating immunosuppressive mechanism of Microplitis bicoloratus bracovirus coordinately fights Spodoptera frugiperda.

Parasitoid wasps control pests via a precise attack leading to the death of the pest. However, parasitoid larvae exhibit self-protection strategies against bracovirus-induced reactive oxygen species impairment. This has a detrimental effect on pest control. Here, we report a strategy for simulating Microplitis bicoloratus bracovirus using Mix-T dsRNA targeting 14 genes associated with transcription, translation, cell-cell communication, and humoral signaling pathways in the host, and from wasp extracellular superoxide dismutases. We implemented either one-time feeding to the younger instar larvae or spraying once on the corn leaves, to effectively control the invading pest Spodoptera frugiperda. This highlights the conserved principle of "biological pest control," as elucidated by the triple interaction of parasitoid-bracovirus-host in a cooperation strategy of bracovirus against its pest host.

Accumulation of phenanthrene by roots of intact wheat (Triticum acstivnm L.) seedlings: passive or active uptake?

BACKGROUND: Polycyclic aromatic hydrocarbons (PAHs) are of particular concern due to their hydrophobic, recalcitrant, persistent, potentially carcinogenic, mutagenic and toxic properties, and their ubiquitous occurrence in the environment. Most of the PAHs in the environment are present in surface soil. Plants grown in PAH-contaminated soils or water can become contaminated with PAHs because of their uptake. Therefore, they may threaten human and animal health. However, the mechanism for PAHs uptake by crop roots is little understood. It is important to understand exactly how PAHs are transported into the plant root system and into the human food chain, since it is beneficial in governing crop contamination by PAHs, remedying soils or waters polluted by PAHs with plants, and modeling potential uptake for risk assessment. RESULTS: The possibility that plant roots may take up phenanthrene (PHE), a representative of PAHs, via active process was investigated using intact wheat (Triticum acstivnm L.) seedlings in a series of hydroponic experiments. The time course for PHE uptake into wheat roots grown in Hoagland solution containing 5.62 microM PHE for 36 h could be separated into two periods: a fast uptake process during the initial 2 h and a slow uptake component thereafter. Concentration-dependent PHE uptake was characterized by a smooth, saturable curve with an apparent Km of 23.7 microM and a Vmax of 208 nmol g(-1) fresh weight h(-1), suggesting a carrier-mediated uptake system. Competition between PHE and naphthalene for their uptake by the roots further supported the carrier-mediated uptake system. Low temperature and 2,4-dinitrophenol (DNP) could inhibit PHE uptake equally, indicating that metabolism plays a role in PHE uptake. The inhibitions by low temperature and DNP were strengthened with increasing concentration of PHE in external solution within PHE water solubility (7.3 muM). The contribution of active uptake to total absorption was almost 40% within PHE water solubility. PHE uptake by wheat roots caused an increase in external solution pH, implying that wheat roots take up PHE via a PHE/nH+ symport system. CONCLUSION: It is concluded that an active, carrier-mediated and energy-consuming influx process is involved in the uptake of PHE by plant roots.

[Preparation of nanocrystalline goethite (alpha-FeOOH) by gel-network precipitation method and spectral properties].

Iron oxyhydroxides (FeOOH), as an environmental mineral material, can adsorb and coprecipitate the contamination from the medium. The ability of removing contamination is decided by the morphology and structural characteristic and the synthesis methods of the obtained mineral. In the present, the used synthesis methods of iron oxyhydroxides (FeOOH) include ferric iron hydrolyzation and ferrous chemical oxidation. But the products of iron oxyhydroxides prepared by these two chemical methods are easily agglomerated and form bigger particles. Thus, in the present study, a novel gel-network precipitation method was developed to synthesize the nanoparticles of goethite (alpha-FeOOH) as environmental mineral material. During formation of alpha-FeOOH nanoparticles by this method, FeCl3 acted as the reaction material and glutin played a role of the reaction medium, which prevents the presence of agglomeration of precipitate particles. So the obtained alpha-FeOOH nanoparticles had smaller size, no aggregation and basic monodispersity, compared with that prepared by the coprecipitation method. At the same time, we introduced the spectrum analysis measures, and studied the effect of different concentration of glutin and FeCl3 solution on the crystallizability and morphology of products. The structure and morphology of alpha-FeOOH nanocrystallites were determined by means of XRD, FTIR and SEM. The results of the spectrum analysis showed that the particle sizes and shapes and crystallizability of the obtained alpha-FeOOH precipitate products were highly related to the network structure of gelatin. And the goethite particles with better monodispersity, prepared by the optimum concentrations of glutin (12%) and FeCl3 solution (0.6 mol x L(-1)), had a short rod-type shape approximately 110 nm in length with an average diameter of about 35 nm.

[Spectral analysis of FeOOH prepared through hydrolysis and neutralization of ferric solutions under different conditions].

In the present work, the iron oxyhydroxides were prepared by hydrolysis and neutralization of ferric ion from FeCl3, Fe(NO3)3 and Fe2 (SO4)3 salts, under the conditions of various pH values and aging for about 6 days at 60 degrees C. These iron minerals were identified and characterized using X-ray diffraction (XRD), infrared spectroscopy (IR) and scanning electron microscopy (SEM). In addition, particle size distributions of FeOOH suspension were also determined by LS-230 model laser grainsize analyzer. Results showed that ferrihydrite formed in the ferric solutions containing Cl-, NO3- and SO4(2-) at pH values of 8 and 10. It was testified that the presence of Cl- was favorable for the formation of akaganéite. Meanwhile, the poor crystalline goethite phase was observed to be formed in FeCl3 or Fe(NO3)3 solution, but not be formed in Fe2 (SO4)3 solution at pH 12. It indicated that the presence of SO4(2-) obviously inhibited the formation of goethite. However, the goethite phase formed in Fe2 (SO4)3 solution with addition of ferrous ion, indicating that ferrous ion could promote the formation of goethite in SO4(2-) -rich solution. In addition, it was usually easy for the crystalline goethite to be transformed from the above generated ferrihydrite precipitates by aging at 60 degrees C. Furthermore, the phase of akaganéite also was obtained in the Cl(-) -rich acid (pH < or = 5) solution by aging at 60 degrees C. In conclusion, the prepared FeOOH samples show some differences in their properties such as the phase, surface properties, morphology structures and particle size.

Enhanced Cr bioleaching efficiency from tannery sludge with coinoculation of Acidithiobacillus thiooxidans TS6 and Brettanomyces B65 in an air-lift reactor.

Bioleaching process has been demonstrated to be an effective technology in removing Cr from tannery sludge, but a large quantity of dissolved organic matter (DOM) present in tannery sludge often exhibits a marked toxicity to chemolithoautotrophic bioleaching bacteria such as Acidithiobacillus thiooxidans. The purpose of the present study was therefore to enhance Cr bioleaching efficiencies through introducing sludge DOM-degrading heterotrophic microorganism into the sulfur-based sludge bioleaching system. An acid-tolerant DOM-degrading yeast strain Brettanomyces B65 was successfully isolated from a local Haining tannery sludge and it could metabolize sludge DOM as a source of energy and carbon for growth. A combined bioleaching experiment (coupling Brettanomyces B65 and A. thiooxidans TS6) performed in an air-lift reactor indicated that the rates of sludge pH reduction and ORP increase were greatly improved, resulting in enhanced Cr solubilization. Compared with the 5 days required for maximum solubilization of Cr for the control (single bioleaching process without inoculation of Brettanomyces B65), the bioleaching period was significantly shorten to 3 days for the combined bioleaching system. Moreover, little nitrogen and phosphorous were lost and the content of Cr was below the permitted levels for land application after 3 days of bioleaching treatment.

[Characterization and heavy metal adsorption properties of schwertmannite synthesized by bacterial oxidation of ferrous sulfate solutions].

An amorphous ferric hydroxysulfate named schwertmannite was synthesized by using bacterial oxidation of ferrous iron by resting A. ferrooxidans cells in acid ferrous sulfate solution (pH 2.5). The identification of the bacterially oxidized iron precipitate was carried out by SEM, XRD, FTIR and chemical analysis. Results showed that resting cells of A. ferrooxidans LX5 could completely oxidize ferrous ions to ferric ions in the FeSO4-H2O system after 2 days of incubation. The solution pH decreased from an initial 2.5 to 2.10, and about 15% of the ferrous iron was transformed into the red-brown precipitates. The subsequent characterization of the precipitates showed that the biotic, synthetic ferric hydroxysulfate was schwertmannite. Sorption edge measurement showed that the adsorption behavior of metal cations (e. g., Cu2+, Zn2+ and Cr3+) was pH-dependent. The adsorption increased with an increase in pH, and the maximum was found in a pH range of 6.0-7.0. For solution concentration of 50 mg x L(-1), the maximum adsorption efficiencies of Cu2+, Zn2+ and Cr3+ were 99.3%, 99.4% and 87.6%, respectively.

Removal of Cr from tannery sludge by bioleaching method.

Bioleaching of Cr(Ill) from tannery sludge using the mixture of ingenuous iron- and sulfur-oxidizing bacteria was investigated in batch flasks. Experiments involved the adaptation of indigenous iron- and sulfur-oxidizing bacteria, the pre-acidification the sludge to pH 6.0 and the addition of energy substrates. Results showed the inoculation of mixture of ingenuous iron- and sulfur-oxidizing bacteria and co-addition of Fe2+ and elemental sulfur accelerated acid production and increase of oxidation-reduction potential originating from the bio-oxidation of Fe2+ and elemental sulfur. Dissolved Cr concentration increased concomitant with pH decreased in the sludge and reached its maximum removal of 95.6%. The amelioration of the odor of bioleached sludge could be noted. However, 20.4% of N, 24.5% of P and 14.3% of organic matter were lost in the bioleaching process. The residual Cr content in the leached tannery sludge was acceptable for use in agriculture. This study had shown the feasibility of applying the bioleaching process, developed for sewage sludge, to tannery sludge with high Cr.

[Adsorption and coprecipitation of dissolved metals with jarosite under conditions simulating sewage sludge bioleaching].

The inoculation of Acidithiobacillus ferrooxidans and the addition of Fe2+ as their substrates accelerated the solubilization of Zn, Cu and Cr from sewage sludge. However, a decrease in Cu removal from 91% to 60% with time elapse could be observed in the late process, which appeared simultaneously with the formation of jarosite resulting from hydrolysis of Fe3+. The tested jarosite was synthesized by using bacterial oxidation of Fe2+ by resting A. ferrooxidans in acid solution (pH 2.5) under conditions stimulating sludge bioleaching. Adsorption edge measurement showed that only less than 9% of Cu2+ was adsorbed onto jarosite in the pH range of 2.0-2.5, indicating that adsorption mechanism could not explain fully re-sorption of Cu2+ (about 31%) in the anaphase of bioleaching process. In the coprecipitation studies, when jarosite was precipitated in the presence of Cu2+ (10 mg x L(-1)), a significant amount of Cu (44.6%) was incorporated into the precipitate. Coprecipitation of jarosite with Cu2+ was the predominant process by which soluble Cu was partially re-sorpted by jarosite in the anaphase of bioleaching process.

[Spectral analysis of dissolved organic matter derived from rice straw after chemical treatment].

Fourier transform infrared spectroscopy (FTIR), ultraviolet spectroscopy (UV), and nuclear magnetic resonance spectroscopy (NMR) were used to study the chemical composition of Dissolved Organic Matter (DOM) derived from rice straw in the hydrolysis process with a dilute complex acid solution. The results obtained are as follows. FTIR spectra could indicate the changes of DOM during the hydrolysis process of rice straw. With the progress of rice straw hydrolysis, methyl, methylene, aromatic compounds and carbohydrates decreased, most of aliphatic compounds were oxidized to CO2 and H2O, and others were turned into carbonates. Most of the organic silicon was hydrolyzed into inorganic silicon. The proteins, amino acids and other nitrogen were hydrolyzed to NH4+. All the recalcitrant fractions of rice straw, such as hemi-cellulose, cellulose and silicon sharply decreased during the process of chemical treatment. The results obtained in this paper proposed that the changes of DOM of rice straw in the hydrolysis could be an indication in the changes of chemical composition of rice straw during the hydrolyzation, and FTIR, UV and NMR were good methods to study the changes in the structure of organic compounds.

[Biosynthetic schwertmannite as catalyst in Fenton-like reactions for degradation of methyl orange].

Biosynthesized schwertmannite was used as catalyst in photo-Fenton-like reaction to facilitate the degradation of methyl orange (MO). Schwertmannite was synthesized through the oxidation of FeSO4 by Acidithiobacillus ferrooxidans LX5 cell suspension at an initial pH 2.5 and 28 degress C for 3 days and characterized using X-ray diffraction spectroscopy and scanning electron microscope. The oxidative degradation of MO in the photo-Fenton-like reaction was studied at different initial pH values of suspension, concentrations of H2O2 and dosages of catalyst. The results suggested that the biosynthetic schwertmannite showed a good catalytic activity in the MO degradation via *OH radical mechanism. Considerable degradation efficiency of MO was still obtained in approximately neutral condition or in the presence of high concentrations of chloride, sulfate and nitrate. This work demonstrated that the heterogeneous photo-Fenton-like reaction catalyzed by the biosynthetic schwertmannite is a promising advanced oxidation technology for the treatment of wastewater containing MO.

[Biosynthesis and characterization of jarosite].

A yellow ochre-colored jarosite was synthesized by bacterial oxidation of ferrous ion by Thiobacillus ferrooxidans at 28 degrees C and 1 atm. The identification of the bacterially oxidized ion precipitate was carried by SEM, XRD, FTIR and chemical analysis. Results showed that resting T. ferrooxidans cells could completely oxidize ferrous ions to ferric ions in FeSO4-K2SO4-H2O system at pH 2.5. In the presence of suitable monovalent K+ and excess sulfate, the yellow precipitate was produced from bacterially oxidized iron solutions. The subsequent characterization showed that it was high-quality jarosite without by-product such as amorphous ferric hydroxysulfates.

[Photochemical degradation of landfill leachate facilitated by combined schwertmannite and H2O2].

It is practically important that high concentrations of organic pollutants in landfill leachate were degraded by a rapid and efficient approach. The influence of operating conditions such as schwertmannite dosage, V(H2O2)/m (schwertmannite) ratio on the degradation efficiency of color, TOC and COD contents of landfill leachate, was investigated by using the schwertmannite/H2O2/UV process. It was demonstrated that the color, TOC and COD removal efficiencies increased significantly with the increase in schwertmannite dosage, and then were approximately stable. However, COD removal efficiency declined because of the presence of the residual H2O2 when V (H2O2)/m (schwertmannite) was greater than 2, and the best removal efficiency of COD was 44.9%. Furthermore, high-intensity ultraviolet was more conducive to eliminate pollutants through photochemical oxidation with schwertmannite/H2O2. The color, TOC and COD removal efficiencies were 90.0%, 78.8% and 52.6% respectively after 2.5 hours of photochemical degradation, with UV-500 W under optimal initial pH = 2.5; meanwhile, this study found that it was beneficial to the photochemical degradation of leachate at room temperature via the schwertmannite/H2O2/UV process, and COD removal efficiency declined gradually when the temperature was higher than 25 degrees C. Controlled trials showed that the schwertmannite/H2O2 method was conducive to the removal of color compared with the traditional homogeneous Fenton reaction.

[Optimization of extracellular polymeric substance extraction method and its role in the dewaterability of sludge].

Seven commonly adopted extraction schemes were selected to extract extracellular polymeric substance (EPS) from the sludge, and the dewaterability of sludge was also investigated before and after extracting EPS. Results showed that Formaldehyde + NaOH and 2% EDTA methods were proved to be effective in extracting EPS from the sludge, and the total EPS production of the total suspend solid was 128.86 mg x g(-1) and 42.38 mg x g(-1), respectively. However, the cell destructed seriously after extracted by Formaldehyde + NaOH and 2% EDTA methods. Heating method was a gentle and efficient method, and the total EPS production was 21.97 mg x g(-1). Sludge dewaterability was largely improved after extracted slime, loosely bound EPS and tightly bound EPS from the sludge flocs. It was also found that the higher content of EPS in slime, the worse dewaterability of sludge, and sludge dewaterability would be deteriorated when EPS was released from other layers to slime. Capillary suction time (CST) values of sludge from the ShekWuHui and Stonecutters Island Treatment works were 132.9 s and 229.9 s compared to 80.8 s and 79.4 s, separately after extracted Slime from sludge flocs, and the dewaterability of sludge was greatly improved.

Scavenging of BHCs and DDTs from soil by thermal desorption and solvent washing.

Intensive remediation of abandoned former organochlorine pesticides (OCPs) manufacturing areas is necessary because the central and surrounding soils contaminated by OCPs are harmful to crop production and food safety. Organochlorine and its residues are persistent in environments and difficult to remove from contaminated soils due to their low solubility and higher sorption to the soils. We performed a comprehensive study on the remediation of OCPs-contaminated soils using thermal desorption technique and solvent washing approaches. The tested soil was thermally treated at 225, 325, 400, and 500 °C for 10, 20, 30, 45, 60, and 90 min, respectively. In addition, we tested soil washing with several organic solvents including n-alcohols and surfactants. The optimal ratio of soil/solvent was tested, and the recycling of used ethanol was investigated. Finally, activities of polyphenol oxidase (PPO), urease (URE), alkaline phosphatase, acid phosphatase (ACP), and invertase (INV) were assayed in the treated soils. The tested soil was thermally treated at 500 °C for 30 min, and the concentration of contaminants in soil was decreased from 3,115.77 to 0.33 mg kg(-1). The thermal desorption in soil was governed by the first-order kinetics model. For the chemical washing experiment, ethanol showed a higher efficiency than any other solvent. Using a 1:20 ratio of soil/solvent, the maximum removal of OCPs was achieved within 15 min. Under this condition, approximately 87 % of OCPs was removed from the soils. More than 90 % of ethanol in the spent wash fluid could be recovered. Activities of some enzymes in soils were increased after ethanol treatment. But ALP, ACP, and INV activities were decreased and PPO and URE showed slightly higher activities following remediation by thermal treatment. Both heating temperature and time were the key factors for thermal desorption of OCPs. The n-alcohol solvent showed higher removal of OCPs from soils than surfactants. The highly efficient removal of OCPs from soil was achieved using ethanol. More than 90 % of ethanol could be recovered and be reused following distillation. This study provides a cost-effective and highly efficient way to remediate the OCPs-contaminated soils.

[Effects of different temperatures biochar on adsorption of Pb(II) on variable charge soils].

Effects of incorporation of the biochars generated from rice straw and peanut straw at different temperatures on soil pH and Pb(II) adsorption were investigated with two variable charge soils. The soil pH increased by 1.04-3.00 units, and the increase in soil pH increased with the rise of pyrolysis temperature of the biochar. Results from adsorption isotherm experiments indicated that the incorporation of the biochar enhanced the adsorption of Pb(II) by two soils. The adsorption of Pb(II) was increased by 12.6% -57.6%, when the initial concentration of Pb(II) is 2 mmol x L(-1). The adsorption also increased with rising pH. Freundlich and Langmuir equations can be used to fit the adsorption isotherms of Pb(II), but the Freundlich equation fitted the adsorption data better, the r-values are above 0.94. Soils incorporated with peanut straw char have a greater adsorption capacity for Pb(II) than these incorporated with rice straw char as predicted by the parameters of k and Q(m) in Freundlich and Langmuir equations, respectively. The biochars generated at 400 degrees C have a greater enhancement on Pb(II) adsorption by soils than 300 degrees C and 500 degrees C. Desorption results showed that the desorption of Pb(II) for the treatments with biochar added was greater than that for the control, but the amount of desorbed Pb(II) was much lower than that of adsorbed Pb(II). These results suggested that the enhanced adsorption of Pb(II) by incorporation of the biochars involved at least two mechanisms: electrostatic adsorption and non-electrostatic adsorption.

[Effect of temperature on activity of Acidithiobacillus ferrooxidan and formation of biogenic secondary iron minerals].

In this study, batch experiments were performed to investigate the effect of temperature on the Fe (II) oxidation and the formation of biogenic secondary iron minerals by Acidithiobacillus ferrooxidan. Results showed that the low temperature significantly inhibited the oxidation activity of A. ferrooxidan. In the FeSO4-H2O biological oxidation system facilitated by A. ferrooxidan, it was found that after 5 days culture, the oxidation rates of Fe (II) in treatments of 10 degrees C and 28 degrees C were 11.81% and 100%, respectively. In addition, it rapidly rose to 95.10% when the temperature was adjusted from 10 degrees C (cultured for 7 days) to 28 degrees C in 1 day, and the maximum oxidation rates were as follows: 10 degrees C (cultured for 7 days) +28 degrees C (2.25 h(-1)) > 28 degrees C (1.42 h(-1)) >10 degrees C (0.81 h(-1)). Furthermore, the XRD patterns showed that the lower Fe (III) supply rate was more conducive to the formation of amorphous schwertmannite in 9K medium at 10 degrees C. Correspondingly, the generation of amorphous schwertmannite was preceded to ihleite at 28 degrees C, and the crystallinity degree of ihleite was getting better with the extension of culture time. Combined with the SEM characteristics, it was judged that the 28 degrees C sample contained jarosite and schwertmannite.

[Effect of microbial nutrient concentration on improvement of municipal sewage sludge dewaterability through bioleaching].

In this study, shaking flask batch experiments and practical engineering application tests were performed to investigate the effect of microbial nutrient concentration on the dewaterability of municipal sewage sludge with 2%, 3%, 4% and 5% solid contents via bioleaching. Meanwhile, the changes of pH value and the utilization efficiency of microbial nutrients during bioleaching were analyzed in this study. The results showed that the pH value decreased gradually at the beginning and then maintained a stable state in the treatments with different solid contents, and the nutrients were completely used up by the microorganisms after 2 days of bioleaching. It was found that the SRF of 2%, 3%, 4%, 5% sludges decreased quickly and then rose gradually with the extension of bioleaching time. In addition, the higher solid content the greater the increase. It was determined that the optimum microbial nutrient dosage for sludge with solid content of 2%, 3%, 4% and 5% were 3.0 g x L(-1), 4.5 g x L(-1), 8.3 g x L(-1) and 12.8 g x L(-1) respectively. At this point, the lowest SRF of sludge with each solid content were 0.61 x 10(12) m x kg(-1), 1.22 x 10(12) m x kg(-1), 3.09 x 10(12) m x kg(-1) and 4.83 x 10(12) m x kg(-1), respectively. Through the engineering application, it was showed that diluting the solid content of sewage sludge from 5% to 3% before bioleaching was feasible. It could not only improve the dewaterability of bioleached sewage sludge (the SRF declined from 3.29 x 10(12) m x kg(-1) to 1.10 x 10(12) m x kg(-1)), but also shorten the sludge nutrient time (shortened from 4 days to 2.35 days) and reduce the operation costs. Therefore, the results of this study have important significance for the engineering application of bioleaching of municipal sewage sludge with high solid content.