Production of high purity humic acid with desirable quality properties for different uses is dependent on extraction and purification methods in its production process. The research literature showed that, in order to achieve this, separation of fulvate compounds and inorganic elements from alkaline humate extracted from raw materials is paramount significant. The main purpose of this study was the separation of alkaline humates from fulvates and inorganic elements by membrane separation technology. Spent mushroom compost (SMC) was used as organic waste for extraction of humic compounds including humates and fulvates with alkaline treatment method. Then, a membrane separation process with a mini-pilot system equipped with frame and plate module and polysulfone membrane with molecular weight cut-off 5 kDa was tested. The effect of transmembrane pressure (TMP) with four levels of 50, 150, 250 and 350 kPa on separation performance including permeate flux of fulvates, predominant fouling mechanism, fouling index (i) and fouling resistances as well as chemical and spectral properties and purity percentage of the resulting humic acid ultrafiltered from humate retentates were investigated. The results of this study showed that by increasing of pressure, permeate flux of fulvate compounds increased by 41. 8%. Based on the Hermia model, the predominant fouling mechanism in all pressure levels were cake layer formation. The results of the fouling index (i) showed that all of the fouling mechanisms occurred in the membrane system, and by increasing pressure, complete pores blocking and cake layer formation were occurred faster and earlier respectively. Scanning electron microscopy (SEM) analysis in order to confirm of experimental data of fouling phenomenon showed that by increasing pressure from 50 to 350 kPa, layer thickness accumulated on the membrane surface was increased 3-fold. Evaluation of ultrafiltered humic acid characteristics showed that membrane separation technology played an effective role on chemical and spectral properties of humic acid compared to other purification methods, and increased final purity of humic acid to 87. 8%.

Humic substances (HS) are complex and heterogeneous materials with different sizes produced through decomposition and transformation of plant and microbial residues by chemical and biochemical processes. HS producers, consumers and also regulators have a great interest to find a precise and accurate method for quantification of HS due to increasing use of them in agriculture. Since there is no distinct definition and consistent chemical structure for HA, an accurate quantification method has not been developed. There are four laboratory methods for determination of HA, FA, humates, and HA derivations (e. g. humate extracts) in commercial fertilizers. These methods include; ISO 5073 titrimetric method that has been published as national standard 11094, a colorimetric method that has been developed according to Mehlich method (1984), and two gravimetric methods that one of them has been developed by California Department of Food and Agriculture (CDFA) and other one is called New Standardized Method (NSM). All of these methods are based on the solubility of HS in dilute alkali solutions. Moreover, FA and other alkali soluble materials e. g. amino acids, proteins, sugars and fatty acids are extracted and measured in colorimetric and titrimetric methods as HA, hence these methods overestimate HA content. The NSM method has obtained by modification of classical method and is based on extraction of HA and FA from natural substances. In this method the separation of FA from other strong base extractable substances such as polysaccharides, amino acids, proteins, and lipids is possible. Also, the NSM method has been accepted by International Humic Substances Society (IHSS) and Humic Products Trade Association (HPTA) and it is the base of standard method that has been developed by International Organization for Standardization (ISO 19822). Therefore, the NSM method is recommended as a reference method.

Catalytic ozonation is a new and promising process used to remove the contaminants from drinking water and wastewater. This study aimed to evaluate the catalytic potential of nano-magnesium oxide (nano-MgO) for the removal of humic acids (HA) from water. Mg (NO3)2 solution was used to prepare MgO powder by the calcination method. In a semi-batch reactor, the catalytic ozonation was carried out. The effects of the various operating parameters, including pH, reaction time, T-butyl alcohol (TBA) and phosphate on HA degradation were evaluated. Experimental results indicated that degradation of HA was increased as the pH solution and reaction time were increased. Maximum HA degradation was obtained at pH=10 and the reaction time of 10 minutes in the catalytic process. The calculated catalytic potential of nano-MgO on ozonation of HA was 60%. Moreover, catalytic ozonation process was not affected by TBA and the main reaction on HA degradation HA have effect take place on MgO surface. According to the results of this study, the developed MgO catalyst is the active and proficient catalyst in HA degradation using the catalytic ozonation process.

Due to the significant impact of humic substances on a variety of environmental processes, knowing the chemical, spectroscopic and structural features of these substances should always be considered in studies related to the management and remediation of the impacted ecosystems. In this study, after the extraction and purification of Humic Acid (HA) from low grade coals of mines of IRAN, the gravimetric technic was used in order to determine the degree of purity of HA from non-destructive spectroscopies such as ICP-OES, UV-VIS, FT-IR and CHNOS for measuring the quality and quantity of HA. Also, microstructures of SEM were used in order to study the structure of HA; then the obtained results were compared with standard Aldrich HA. The results of the gravimetric analysis showed that the produced HA had a 98% degree of purification. Also, from the view of quantity, the results of elemental analysis of ICP-OES indicated that after the purification of HA, the concentration of various heavy metals in HA are lower than the recommended safety limit and there is a range of both macronutrients and micronutrients in the structure of HA. Moreover, the quality results of FT-IR, UV-VIS and SEM analysis have shown the presence of an aromatic predominant structure, rich in carboxylic and phenolic functional groups with high humification and condensation degrees, and type A with a loose spongy and heterogeneous porous surfaces for HA. The CHNOS analysis also confirmed the suitability of the coal used to extract HA, and showed that the final product matches the standard HA results.

Introduction and Objective: Nowadays the effective role of organic matter has been proven in improving soil productivity. Regarding to sensitivity of sustainable organic matter component to different land use practices in addition to the organic matter, investigation of changes in its compound is important. Determining the evaluation of organic matter and amount of carbon stabilization in soil system, and their quality and quantity will be varied according to the type of land use. Material and Methods: Due to extensive land use in the north of Iran, present study focused on effect of these uses on the content of organic matter and its humic components. In this regard a study was carried out in five land use including: beech forest, Fraxinus plantation, black pine plantation, degraded forest and agriculture in Tajan watershed. Eight points were selected in each site and soil samples were taken at a 25 × 25 area to a depth of 15 cm. Results: Highest of organic matter (4. 68 %), fulvic acid (668. 750 mg/100 gr soil) and humic acid (976. 620 mg/100 gr soil) were observed in agriculture land cover. Some soil physical, chemical and biological features were also measured. Whole of studied soil characters were significantly different among land covers, except silt content. Conclusion: Though as for the results, highest contribution of organic compounds were observed in agriculture land, according to the PCA analysis, soil nutrition condition and microbial activity were more appropriate in forest stands. More quality of debris along the favorable environmental condition and presence of microbial activity can be attributed to a reduction in rate of accumulation of remains following the process of organic matter decomposition and mineralization in forest stands. The findings of this study suggest that protecting of natural forest is very important. In addition, in degraded areas of northern Iran, planting of Fraxinus excelsior species can be considered due to improvement of soil quality and health.