Production Of Humic Acids Research Articles

Influence of fermentation liquid from waste activated sludge on anoxic/oxic- membrane bioreactor performance: Nitrogen removal, membrane fouling and microbial community

In order to investigate effects of waste activated sludge (WAS) fermentation liquid on anoxic/oxic- membrane bioreactor (A/O-MBR), two A/O-MBRs with and without WAS fermentation liquid addition were operated in parallel. Results show that addition of WAS fermentation liquid clearly improved denitrification efficiency without deterioration of nitrification, while severe membrane fouling occurred. WAS fermentation liquid resulted in an elevated production of proteins and humic acids in bound extracellular polymeric substance (EPS) and release of organic matter with high MW fractions in soluble microbial product (SMP) and loosely bound EPS (LB-EPS). Measurement of deposition rate and fluid structure confirmed increased fouling potential of SMP and LB-EPS. γ-Proteobacteria and Ferruginibacter, which can secrete and export EPS, were also found to be abundant in the MBR with WAS fermentation liquid. It is implied that when WAS fermentation liquid was applied, some operational steps to control membrane fouling should be employed.

Value-Added Humic Acid Derived from Lignite Using Novel Solid-Phase Activation Process with Pd/CeO2 Nanocatalyst: A Physiochemical Study

Soil, air, and water pollution caused by lignite is considered a serious environmental problem. Activation methods thus have been developed to extract humic acid from lignite to support the agricultural production as the soil amendment or fertilizer synergist. The traditional activation methods of humic acid from lignite, however, are not environmentally friendly. As the first study, this work developed a novel solid-phase activation method with a Pd/CeO2 nanocatalyst for lignite-derived humic acid. This study analyzed the morphology and structures of the as-synthesized Pd/CeO2 nanocatalyst with various characterization tools. The mechanisms of the Pd/CeO2 nanocatalyst for lignite activation were determined. The Pd/CeO2 catalyst effectively promoted the production of water-soluble humic acids from lignite via KOH solid-phase activation at room temperature. It increased the amount of small molecular active groups and the corresponding small molecules of humic acid. The existence of a strong synergistic eff...

Production of Humic Acid by a Bacillus megaterium Strain Using Vinasse

Humic acid can be produced by a Bacillus megaterium strain, AS019, using vinasse (sugarcane mill wastewater) at an optimal concentration of 12 °Bx. Using single factor and orthogonal experiments, the optimal culture conditions were determined: optimum inoculum size, 15%; initial pH, 6.0; culture time, 8 days; rotation speed, 180 rpm; and temperature, 28 °C. Under the optimal conditions, the humic acid production rate for the strain was 49.50 g/L. The results of characterization and infrared spectral analysis revealed that the produced humic acid contained a variety of reactive functional groups.

Advantages and risks of using steel slag in preparing composts from raw organic waste

ABSTRACTIt had been reported that iron and manganese oxides in steel slag enhanced the production of humic acid (HA) from low-molecular-weight compounds, such as phenolic acids, amino acids, and saccharides. In the present study, this function of steel slag was applied to the composting of raw organic wastes (ROWs). The degree of humification of HAs is an important factor in evaluating compost quality. Thus, HAs were extracted from the prepared composts and the humification parameters were determined, in terms of elemental compositions, acidic functional group contents, molecular weights, spectroscopic parameters from UV–vis absorption and 13C NMR spectra. The timing for adding steel slag affected the degree of humification of HAs in the composts. The weight average molecular weight of a HA when slag was added initially (29 kDa) was significantly higher than when slag was added after elevating the temperature of the compost pile (17–18 kDa). These results show that ROWs are decomposed to low-molecular-weight compounds after the pile temperature is elevated and the presence of slag enhances the polycondensation of these compounds to produce HAs with a higher degree of humification. Because the slag used in the present study contained several-tens ng g−1 to several μg g−1 of toxic elements (B, Cu, Cr, and Zn), leaching tests for these elements from the prepared composts were carried out. Levels for leaching boron from composts prepared by adding slag (0.2–0.4 mg L−1) were obviously higher than the corresponding levels without slag (0.05 mg L−1).

Heterogeneity of the electron exchange capacity of kitchen waste compost-derived humic acids based on fluorescence components

Composting is widely used for recycling of kitchen waste to improve soil properties, which is mainly attributed to the nutrient and structural functions of compost-derived humic acids (HAs). However, the redox properties of compost-derived HAs are not fully explored. Here, a unique framework is employed to investigate the electron exchange capacity (EEC) of HAs during kitchen waste composting. Most components of compost-derived HAs hold EEC, but nearly two-thirds of them are found to be easily destroyed by Shewanella oneidensis MR-1 and thus result in an EEC lower than the electron - donating capacity in compost-derived HAs. Fortunately, a refractory component also existed within compost-derived HAs and could serve as a stable and effective electron shuttle to promote the MR-1 involved in Fe(III) reduction, and its EEC was significantly correlated with the aromaticity and the amount of quinones. Nevertheless, with the increase of composting time, the EEC of the refractory component did not show an increasing trend. These results implied that there was an optimal composting time to maximize the production of HAs with more refractory and redox molecules. Recognition of the heterogeneity of EEC of the compost-derived HAs enables an efficient utilization of the composts for a variety of environmental applications. Graphical abstract Microbial reduction of compost-derived HAs.

Label Distribution in Tissues of Wheat Seedlings Cultivated with Tritium-Labeled Leonardite Humic Acid.

Humic substances (HS) play important roles in the biotic-abiotic interactions of the root plant and soil contributing to plant adaptation to external environments. However, their mode of action on plants remains largely unknown. In this study the HS distribution in tissues of wheat seedlings was examined using tritium-labeled humic acid (HA) derived from leonardite (a variety of lignites) and microautoradiography (MAR). Preferential accumulation of labeled products from tritiated HA was found in the roots as compared to the shoots, and endodermis was shown to be the major control point for radial transport of label into vascular system of plant. Tritium was also found in the stele and xylem tissues indicating that labeled products from tritiated HA could be transported to shoot tissues via the transpiration stream. Treatment with HA lead to an increase in the content of polar lipids of photosynthetic membranes. The observed accumulation of labeled HA products in root endodermis and positive impact on lipid synthesis are consistent with prior reported observations on physiological effects of HS on plants such as enhanced growth and development of lateral roots and improvement/repairs of the photosynthetic status of plants under stress conditions.

Влияние ботанического состава и степени разложения торфа на элементный состав гуминовых кислот

The subject of the study was the samples of peat are most typical for the middle taiga zone of the West Siberian plain. The purpose of the study is to identify the relationship between the botanical species of the peat, degree of decomposition and chemical composition of the resulting humic acids. The influence of botanical species and decomposition degree of peat on the elemental composition and the practical yield of humic acids were studied. It is shown that the mechanochemical method of obtaining of humic acids can be applied to all kinds of peats of Western Siberia, regardless of botanical species and degree of decomposition. The yield of humic acids from peat directly correlated with the degree of peat decomposition. The use of cavitation of peat for preparation of humic acids eliminates differences in the elemental composition of humic acids obtained from various species of peat raw materials with different degree of decomposition. For the industrial production of humic acids proposed mechanochemical method allows the use of peat, produced by any method, including excavation.

The role of a novel fungal strainTrichoderma atrovirideRVF3 in improving humic acid content in mature compost and vermicompost via ligninolytic and celluloxylanolytic activities

With the rising concerns about indiscriminate use of chemical fertilizers and accumulation of agro-industrial wastes in huge quantities, the present experiment was conducted to elucidate the effect of a novel fungal strain of Trichoderma atroviride in hastening the compost/vermicompost production process and for the production of humic acid (HA) rich compost and vermicompost. Rice (Oryza sativa) straw and distillation waste of geranium (Pelargonium graveolens), two important agricultural/industrial crop wastes were subjected to composting and vermicomposting. T.atroviride strains GVF10 (cellulase and xylanase producing), and RVF3 (ligninase and celluloxylanase producing) were inoculated alone or in combination. The HA content was found to increase maximally in rice vermicompost treated with ligninase producing strain RVF3 (85% with respect to HA standard) followed by geranium vermicompost + RVF3. The addition of the strain GVF10 increased HA content to about 35-62% with respect to HA standard. The addition of the fungal inoculum reduced the composting/vermicomposting time from 110 to 90days. Our results indicate that the use of selected fungal strain(s) hold potential to produce qualitatively superior compost and vermicompost with high HA content in a shorter period. Use of appropriate fungal strains may increase the efficiency of composting/vermicomposting processes producing compost and vermicompost with higher HA content, and alleviating the problems of solid waste accumulation and declining soil fertility.

Membrane bioreactors fed with different COD/N ratio wastewater: impacts on microbial community, microbial products, and membrane fouling.

It is known that an increase of COD/N ratio can result in an enhanced removal of nutrients in membrane bioreactors (MBRs); however, impacts of doing so on membrane filtration performance remain unclear. In this work, comparison of membrane filtration performance, microbial community, and microbial products under low temperature was carried out in anoxic/oxic (A/O) MBRs with COD/N ratios of 9.9 and 5.5 g COD/g N in influent. There was no doubt that an improvement of nitrogen removal under high COD/N ratio was observed; however, severer membrane fouling was found compared to the MBR fed with low COD/N ratio wastewater. The increase of COD/N ratio resulted in an elevated production of humic acids in soluble microbial product (SMP) and carbohydrates, proteins, and humic acids in loosely bound extracellular polymeric substance (LB-EPS). Quartz crystal microbalance with dissipation monitoring (QCM-D) analysis showed that the adsorption capability of SMP and LB-EPS was higher in the MBR with higher COD/N ratio. Four hundred fifty four high-throughput pyrosequencing revealed that the higher COD/N ratio led to the enrichment of Bacteroidetes at phylum level and Azospira, Thauera, Zoogloea, etc. at genus level. Bacteroidetes are considered to potentially release EPS, and Azospira, Thauera, and Zoogloea, etc. have denitrification activity. The change in microbial communities is consistent with MBR performance.

Chlorine Dioxide Mediated Oxidation of Sub-Bituminous Coal for Humic Acid Production

Chlorine Dioxide Mediated Oxidation of Sub-Bituminous Coal for Humic Acid Production

Development of growth media for solid substrate propagation of ectomycorrhizal fungi for inoculation of Norway spruce (Picea abies) seedlings.

A silica-based propagation medium was developed for large-scale production of ectomycorrhizal (ECM) fungal inoculum by solid state fermentation. Development of the medium was started by screening for an optimal growth medium among six different semisynthetic agar media traditionally used in cultivation of ECM fungi. The majority (65 %) of the twenty tested ECM fungal strains that typically colonize Norway spruce (Picea abies) seedlings grew best on modified Melin-Norkrans (MMN) medium with reduced sugar content (½MMN). In order to develop a nutritionally similar medium for large-scale cultivation of the ECM fungi, we chose silica to form a solid matrix and light brewery malt extract to provide nutrients. The medium was supplemented with a commercial humic acid product that was shown to boost fungal growth. The optimal concentration of the constituents was screened for in two assays by determining the growth rates of seven potential inoculant ECM fungal strains (Amphinema sp., Cenococcum geophilum, Hebeloma sp., Meliniomyces bicolor, Paxillus involutus, Piloderma byssinum, and Tylospora asterophora). As a result, we composed a silica-based mass propagation medium (pH 5.8) containing 2.5 % brewery malt extract and 0.5 g/l humic acid product Lignohumate AM. This medium is easily produced and supported good growth of even the slowly growing and rarely studied Athelioid ECM strains. Furthermore, root systems of Norway spruce nursery seedlings were colonized by the tested ECM fungi by using solid inoculum formulated from the silica medium.

Biochar but not humic acid product amendment affected maize yields via improving plant-soil moisture relations

Biochar (BC) and humic acid product (HAP) soil amendments may improve plant performance under water-limited conditions. Our aim was to investigate if BC and HAP amendments, alone or in combination, will have positive and synergistic effects. A three-factorial fully randomized study was carried out in the greenhouse for 66 days, including the factors ‘BC’, ‘HAP’ and ‘water regime’. Maize (Zea mays var. ‘Amadeo’ DKC-3399) was grown in pots (6 kg sandy soil pot−1) amended with/without BC (0, 1.5 and 3 %; w/w) and with/without HAP (0 or an equivalent of 8 kg ha−1). Two water regimes, limited and frequent (H2O limit , H2O frequ ), were applied after day 28 following seedling establishment at 60 % water holding capacity (WHC). In the H2O limit treatment, the soil water content was allowed to drop until wilting symptoms became visible (25–30 % WHC) while in H2O frequ the WHC was brought to 60 % of the maximum on a daily basis BC but not HAP, added alone or in combination with BC, significantly increased the biomass yield and the water and N use efficiency of plants at both water regimes. The BC-mediated relative increase in the yield was equal with both watering regimes, refuting initial hypotheses. BC had generally a stimulating effect on water relations and photosynthesis, it increased the relative water content and the leaf osmotic potential, decreased the stomatal resistance and stimulated the leaf gas exchange (transpiration). Both, BC and pure HAP addition, stimulated photosynthesis by increasing the electron transport rate (ETR) of photosystem II (PSII) and of the ratio between effective photochemical quantum yield to non-photochemical quenching (Y(II)/Y(NPQ), revealing reduced heat dissipation. Biochar use in poor sandy soils can improve plant growth by improving soil-plant water relations and photosynthesis under both H2O frequ and H2O limit conditions. HAP loading, however, did not improve the effect of biochar or vice versa.

English

The remarkable properties of humic acids have generated a broad spectrum of applications in pharmaceutical, cosmetic and agricultural fields, and encouraged fermentation studies focusing on humic acids production. This work compares the humic acids production of Trichoderma (viride and reesei) species using empty fruit bunch as the substrate during submerged fermentation. The performance of each species was compared by examining spore production in oat medium, and the significant medium components and fermentation conditions were identified using Plackett and Burman statistical design. For both Trichoderma species, the results indicate that humic acids production can be enhanced by increasing the temperature, empty fruit bunch and peptone concentrations and by decreasing the (NH4)2SO4 concentration. T. reesei performed better than T. viride, generating 3-fold more of humic acids.   Key words: Humic acids, Trichoderma reesei, Trichoderm aviride, submerged fermentation, empty fruit bunch.

Solid-State Fermentation for Humic Acids Production by a Trichoderma reesei Strain Using an Oil Palm Empty Fruit Bunch as the Substrate

Empty fruit bunch (EFB), an underutilized waste product of oil palm processing, was studied as a substrate for the production of humic acids (HA) by a Trichoderma reesei strain by solid-state fermentation (SSF) in Raimbault columns. HA have attracted the attention of many investigators due to their applications in agriculture, industry, the environment, and biomedicine. Commercial HA are currently chemically extracted from peat and coal, which are nonrenewable carbon sources. Biotechnological processes are important for their sustainable and controlled production, with SSF being especially promising for mimicking the natural habitat of fungi. Trichoderma sporulation and HA production are related, and the results of this study showed that SSF stimulated fast sporulation. The productivity related to HA was much higher than that of the biomass, indicating an efficient utilization of EFB. These findings, added to the low cost of EFB, make SSF an attractive process for HA production.

Production of humic acids from oil palm empty fruit bunch by submerged fermentation with Trichoderma viride: Cellulosic substrates and nitrogen sources

The novelty of this study was to produce humic acids by submerged fermentation of empty fruit bunch (EFB) with Trichoderma viride and to investigate the effects of the cellulosic substrates and the organic sources of nitrogen on the biotechnological production of these acids. The results obtained indicate the potential application of EFB, a waste of oil palm processing, for humic acids production. Because EFB contains cellulose, hemicellulose and lignin, fermentations were also performed using these polymers as carbon sources, separately or in combination. After 120 h of fermentation, significant production of humic acids was observed only in cultures containing either EFB or a mixture of the three polymers. Use of either potato peptone or yeast extract as a nitrogen source yielded nearly identical patterns of fungal growth and production of humic acids. The data obtained from microscopic imaging of T. viride growth and sporulation in EFB, coupled with the determined rates of production of humic acids indicated that the production of these acids is related to T. viride sporulation.

Movement of Phosphorus in a Calcareous Soil as Affected by Humic Acid

When humic acid (HA) and phosphorus (P) fertilizer are simultaneously applied to soil, HA may affect the movement of P. A laboratory incubation experiment was conducted to quantify the effects of a commercial HA product co-applied with monocalcium phosphate (MCP) on the distance of P movement and the concentration of P in various forms at different distances from the P fertilizer application site in a calcareous soil from northern China. Fertilizer MCP (at a rate equivalent to 26.6 kg P ha−1) was applied alone or in combination with HA (at 254.8 kg HA ha−1) to the surface of soil packed in cylinders (150 mm high and 50 mm internal diameter), and then incubated at 320 g kg−1 moisture content for 7 and 28 d periods. Extraction and analysis of each 2 mm soil layer in columns showed that the addition of HA to MCP increased the distance of P movement and the concentrations of water-extractable P, acid-extractable P and Olsen P in soil. The addition of HA to MCP could enhance P availability by increasing the distance of P movement and the concentration of extractable P in soil surrounding the P fertilizer.

Biodegradation of Leonardite by an Alkali-producing bacterial community and characterization of the degraded products

In this study, three bacterial communities were obtained from 12 Leonardite samples with the aim of identifying a clean, effective, and economic technique for the dissolution of Leonardite, a type of low-grade coal, in the production of humic acid (HA). The biodegradation ability and characteristics of the degraded products of the most effective bacterial community (MCSL-2), which degraded 50% of the Leonardite within 21 days, were further investigated. Analyses of elemental composition, (13)C NMR, and Fourier transform infrared revealed that the contents of C, O, and aliphatic carbon were similar in biodegraded humic acid (bHA) and chemically (alkali) extracted humic acid (cHA). However, the N and carboxyl carbon contents of bHA was higher than that of cHA. Furthermore, a positive correlation was identified between the degradation efficiency and the increasing pH of the culture medium, while increases of manganese peroxidase and esterase activities were also observed. These data demonstrated that both alkali production and enzyme reactions were involved in Leonardite solubilization by MCSL-2, although the former mechanism predominated. No fungus was observed by microscopy. Only four bacterial phylotypes were recognized, and Bacillus licheniformis-related bacteria were identified as the main group in MCSL-2 by analysis of amplified 16S rRNA genes, thus demonstrating that Leonardite degradation ability has a limited distribution in bacteria. Hormone-like bioactivities of bHA were also detected. In this study, a bacterial community capable of Leonardite degradation was identified and the products characterized. These data implicate the use of such bacteria for the exploitation of Leonardite as a biofertilizer.

Influence of Humic Products on Soil Health and Potato Production

Since 1900, soil organic matter (SOM) in farmlands worldwide has declined drastically as a result of carbon turnover and cropping systems. Over the past 17 years, research trials were established to evaluate the efficacy of different commercial humates products on potato production. Data from humic acid (HA) trials showed that different cropping systems responded differently to different products in relation to yield and quality. Important qualifying factors included: source; concentration; processing; chelating or complexing capacity of the humic acid products; functional groups (Carboxyl; Phenol; Hydroxyl; Ketone; Ester; Ether; Amine), rotation and soil quality factors; consistency of the product in enhancing yield and quality of potato crops; mineralization effect; and influence on fertilizer use efficiency. Properties of humic substances, major constituents of soil organic matter, include chelation, mineralization, buffer effect, clay mineral-organic interaction, and cation exchange. Humates increase phosphorus availability by complexing ions into stable compounds, allowing the phosphorus ion to remain exchangeable for plants’ uptake. Collectively, the consistent use of good quality products in our replicated research plots in different years resulted in a yield increase from 11.4% to the maximum of 22.3%. Over the past decade, there has been a major increase in the quality of research and development of organic and humic acid products by some well-established manufacturers. Our experimentations with these commercial products showed an increase in the yield and quality of crops.

Experimental Study on Extracting Humic Acid from Lignite

Humic acid has been extensively used in the fields like industry, agriculture, medicine, environment protection, etc. As a kind of potential organic resources that being developed and utilized, humic acid is drawing more and more attention from the world. China is abundant in coal resource; the lignite of China contains a lot of humic acid. Extraction humic acid from lignite creates favorable conditions for the development of coal industry and agriculture industry, has broad utilization prospect. By combining the method of nitric acid preoxidation and the method of alkali solution and acid eduction, the humic acid was extracted from the lignite. The orthogonal experimental method and FTIR were integrated in this study. The influences of nitrate concentrations, acid-coal proportion, oxidized temperature, oxidation time, extraction liquid concentration, liquid-solid ratio, extraction temperature and extraction time etc. on the process of extracting humic acid were examined. The results indicate the optimal processing condition can achieved when using sodium pyrophosphate and sodium hydroxide solution as the extraction agents, the rate of humic acid production can reach to 39.25%. And the total content of humic acid production can reach to 46.14%.

Characterization of soluble microbial products (SMP) under stressful conditions

Soluble microbial products (SMP) in the wastewater treatment process not only cause fouling to the membrane, but also generate disinfection by-products (DBP) in the effluent, thus get increasing attention. In this study, SMP produced by activated sludge and isolates under different stressful conditions, i.e. starvation, salinity, heavy metals, low pH and high temperature, were characterized to investigate the effects of these conditions on the amount of SMP and their compositions. The analysis results using size exclusion chromatography (SEC), high pressure liquid chromatography (HPLC) and fluorescence excitation emission matrix (FEEM) showed that activated sludge and isolates suffered with the same stressful condition contained almost the same concentration and composition of SMP, indicating that the stressful condition instead of the microbial species played the crucial role in the production of SMP. Among of stressful conditions tested, high temperature had stimulated the production of polysaccharides and polycarboxylate-type humic acid with high hydrophilicity, which is in positive proportion to the foulants formation potential, thus should be avoided in membrane bioreactors. Low pH had promoted the generation of hydrophobic humic acid-like or protein-like organics, which had been proved as the main disinfection byproduct (DBP) precursor, thus should be avoided in the biological treatment. Starvation had less effect on SMP production as the seeding microbes had no substrates.