Waste Soil Research Articles

Application of 3 D digital technology in transmission line engineering and waste soil disposal mechanization construction

Under the background of the innovation in the field of construction engineering toward the direction of intelligence and digitalization, the three-dimensional digital design means with the digital information model as the core has gradually become the main content of the industry discussion in the new era. According to the cumulative experience of transmission line construction in recent years in our country, three-dimensional digital technology can simulate and arrange the construction link comprehensively during the construction of the project, and shorten the construction period and reduce the cost. Therefore, on the basis of understanding the current situation of transmission line engineering and the mechanized construction of residual soil disposal, this paper deeply discusses how to apply three-dimensional digital technology in the mechanized construction of transmission line engineering and residual soil disposal according to the research situation of three-dimensional digital technology at home and abroad. The final experimental results show that the 3D digital technology has a good application effect during the project construction, which is helpful to guide the high-quality development of power design industry in the new era.

Efficient biodegradation of di-(2-ethylhexyl) phthalate by a novel strain Nocardia asteroides LMB-7 isolated from electronic waste soil

The di-2-ethylhexyl phthalate (DEHP) degrading strain LMB-7 was isolated from electronic waste soil. According to its biophysical/biochemical characteristics and 16S rRNA gene analysis, the strain was identified as Nocardia asteroides. Optimal pH and temperature for DEHP degradation were 8.0 and 30 °C, respectively, and DEHP removal reached 97.11% after cultivation for 24 h at an initial concentration of 400 mg/L. As degradation intermediates, di-butyl phthalates, mono-2-ethylhexyl phthalate and 2-ethylhexanol could be identified, and it could be confirmed that DEHP was completely degraded by strain LMB-7. To our knowledge, this is a new report of DEHP degradation by a strain of Nocardia asteroides, at rates higher than those reported to date. This finding provides a new way for DEHP elimination from environment.

Preparation of lightweight aggregates using waste soil contaminated with heavy metals: Physical properties, microstructure and verification of heavy metal solidification through different leaching tests

Considerable volumes of polluted soil are being discharged around the world resulting in serious pollution. As both Si and Al are important components in the framework of a lightweight aggregate (LWA), polluted soil can be used as a raw material for preparing the LWA. In this study, LWAs were prepared from polluted soil containing Cu, Cr, Ni, and Pb. Tests were conducted to assess their macroscopic, microscopic, and heavy-metal leaching properties. The mechanism underlying heavy metal dissolution and a method to accelerate this dissolution were systematically studied under the condition of monolithic leaching of the LWAs. The solidification state and leaching process of heavy metals under different conditions of the LWA were investigated. The experimental results indicated that the LWA prepared from polluted soil met the LWA standard and new crystalline phases were formed during the sintering process. At the same time, long-term leaching tests and accelerated leaching tests showed that the leaching concentrations of the four heavy metals were all lower than the safety limits specified in Chinese standards. The experiments revealed that the pH, temperature, and ultrasonication could accelerate the dissolution of heavy metals. In particular, ultrasonication caused the heavy metals to exhibit the effects of long-term leaching in a short time. Nevertheless, leaching amount did not exceed the limits specified by the standard, thus improving the our understanding of heavy metal solidification in LWAs. These results could significantly guide the construction industry in establishing an evaluation method for heavy metal dissolution that conforms to the service environment of LWAs, enabling the safe management of solid wastes and the sustainable development of light aggregates.

Effects of agricultural by-product on mechanical properties of cemented waste soil

Waste soil produced from construction sites currently emerges as a big problem to environment. These soils cannot be reused directly cause of its weakness in strength properties. Hence, this study focuses on improving mechanical properties of waste soil by using cement and corn husk fiber . The environment has also benefited from using corn husk fiber since corn husk is agricultural by-product. In order to evaluate the impact of corn husk fiber and cement on mechanical characteristics of waste soil, a series of laboratory experiments containing tension and compression test is carried out. In addition, scanning electron microscopy (SEM) test is conducted to investigate interaction between fibers and soil-cement matrix. Fiber content from 0 to 1% by dry soil mass and corn husk lengths of 10 and 30 mm are used in this research. The results present that strength properties of cemented soil are enhanced when fiber is added. The most improvements corresponding to compressive strength , splitting tensile strength , and direct tensile strength are 30.6%, 206.1%, and 27.9%, respectively. A strong interaction between fibers and soil-cement matrix observed from SEM results in the improvement of strength properties of cemented soil. Fiber inclusion contributes to the more ductile and durable behavior under loading. Fiber length and fiber content have a remarkable effect on the cemented soil behavior. The increase in fiber length and content leads to the increase in residual stress and the decrease in loss of post-peak stress. • Corn husk is utilized in waste soil reinforcement. • Effect of corn husk fiber on cemented soil is investigated. • The addition of fiber delays failure process of cemented soil. • Fiber inclusion improves failure strength up to 206%. • Presence of fibers at crack contributes to the appearance of residual direct tensile stress.

Effects of Restoration Years on Vegetation and Soil Characteristics under Different Artificial Measures in Alpine Mining Areas, West China

In view of the problem of sustainable restoration of vegetation in alpine mining areas, vegetation communities and physical and chemical properties of soil under different artificial restoration measures (i.e., grass monoculture, sowing quantity and topsoil replacement) were investigated for five consecutive years (2016–2020) in the sloped eastern area of a northern slag mound in the Jiangcang mining area of the Muli coalfield in Qinghai, China. The results showed that the vegetation characteristics of different sowing treatments with different kinds of grass species, such as Elymus nutans, Poa pratensis cv. Qinghai and Poa crymophila cv. Qinghai, were significantly different (p < 0.05). The content of soil available nitrogen and phosphorus was significantly different among different grass species (p < 0.05). Vegetation coverage and ramet density of sowing treatment five were significantly higher than those of a lower sowing quantity (p < 0.05). There was no significant difference in the vegetation characteristics among different grass species treatments five years after the restoration (p > 0.05). There was no significant difference in vegetation height of different soil covering treatments (p > 0.05). In the early stage of restoration, vegetation coverage and ramet density in TR2 (resurfacing soil 10 cm) and TR3 (resurfacing soil 15 cm) were significantly higher than those without treatment. Soil N, P and organic matter under the treatments of TR1 (resurfacing soil 5 cm), TR2 and TR3 were significantly higher than those in CK (p < 0.05) in the early stage of restoration, but there was no significant difference in soil N, P and organic matter after five years of restoration. Overall, the vegetation and soil characteristics showed a trend of increase first and then decrease during the 5-year restoration period under different artificial measures. There were significant differences in the vegetation and soil characteristics among different treatments in the second year of restoration (p < 0.05), but there was no significant difference between the first year and the fifth year of restoration, which indicated that vegetation and soil began to degrade after five years of restoration, and substrate nutrients in the mining waste soil could only support the short-term restoration of vegetation. Therefore, it is necessary to target matrix nutrients in future vegetation restoration in alpine mining areas.

Efficient bioremediation of PAHs-contaminated soils by a methylotrophic enrichment culture

Bioaugmentation effectively enhances microbial bioremediation of hazardous polycyclic aromatic hydrocarbons (PAHs) from contaminated environments. While screening for pyrene-degrading bacteria from a former manufactured gas plant soil (MGPS), the mixed enrichment culture was found to be more efficient in PAHs biodegradation than the culturable pure strains. Interestingly, analysis of 16S rRNA sequences revealed that the culture was dominated by a previously uncultured member of the family Rhizobiaceae. The culture utilized C1 and other methylotrophic substrates, including dimethylformamide (DMF), which was used as a solvent for supplementing the culture medium with PAHs. In the liquid medium, the culture rapidly degraded phenanthrene, pyrene, and the carcinogenic benzo(a)pyrene (BaP), when provided as the sole carbon source or with DMF as a co-substrate. The efficiency of the culture in the bioremediation of PAHs from the MGPS and a laboratory waste soil (LWS) was evaluated in bench-scale slurry systems. After 28 days, 80% of Σ16 PAHs were efficiently removed from the inoculated MGPS. Notably, the bioaugmentation achieved 90% removal of four-ringed and 60% of highly recalcitrant five- and six-ringed PAHs from the MGPS. Likewise, almost all phenanthrene, pyrene, and 65% BaP were removed from the bioaugmented LWS. This study highlights the application of the methylotrophic enrichment culture dominated by an uncultured bacterium for the efficient bioremediation of PAHs.

Changes to bacterial communities and soil metabolites in an apple orchard as a legacy effect of different intercropping plants and soil management practices.

Intercropping is an important soil management practice for increasing orchard productivity and land-use efficiency because it has beneficial effects on soil microbial communities and soil properties. However, there is relatively little information available regarding the effects of different crops/grasses on soil microbial communities and soil metabolic products in apple orchards in arid and semi-arid regions. In this study, we showed the microbial communities of apple, intercropping plants, and sandy waste soil, using the third-generation PacBio SMRT long-read sequencing technology. Our results also revealed that the microbial communities and soil metabolic properties differed significantly between apple and the sandy waste soil and the intercropping plants. Intercropping could significantly enrich diverse microbial species, microbial nitrogen, and microbial carbon of soil. Moreover, intercropping with licorice showed better effects in recruiting beneficial microbes, compared to grass and pepper, significantly enriching species belonging to some well-known taxa with beneficial effects, including Bacillus, Ensifer, Paenibacillus, Rhizobium, and Sphingomonas. Thus, intercropping with licorice may improve apple tree growth and disease resistance. Furthermore, Bradyrhizobium and Rubrobacter were included among the keystone taxa of apple, whereas Bacillus, Chitinophaga, Stenotrophobacter, Rubrobacter, and Luteimonas were the keystone taxa of the intercropping plants. The results of our study suggest that intercropping with licorice is a viable option for increasing apple orchard productivity.

Alkali-reinforced hydrothermal solidification of waste soil

To promote the resource utilization of waste soil, hydrothermal solidification technology was used to convert waste soil into a tough material. The effects of curing conditions (time and temperature), molding conditions and alkaline conditions on the physical-mechanical properties of hydrothermally solidified waste soil were investigated in the CaO–MgO–Al2O3–SiO2–H2O system. The solidification mechanism and microstructure evolution under different synthesis conditions were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and low-field nuclear magnetic resonance (NMR). The strength of waste soil was effectively enhanced under hydrothermal conditions; in particular, the addition of NaOH solution could nearly double the strength. Calcium silicate hydrate (C–S–H) and hydrogarnet formed by the hydrothermal reaction filled the pores and cemented mineral particles to form a dense skeleton structure. The filling of hydrothermal products and the dissolution of mineral particles together affected the pore structure and compactness of the material. The synthesis conditions determined the type and quantity of hydrothermal products that affect the microstructure, consequently reflecting the changes in macroscopic physical-mechanical properties.

Optimization of procedural factors for advanced xylanase synthesis by Lysinibacillus fusiformis using Kolanut husk as substrate

Xylan is a complex hetero-polysaccharide consisting of different monosaccharides held together by glycosidic and ester bonds. Extracellular xylanase fashioned by numerous microbes principally from bacterial species such as Bacillus species are responsible for cleaving the glycosidic linkages. Microbial xylanases exhibit different substrate specificities and biochemical peculiarities. This study was carried out for optimization of cultivation conditions for xylanase production using the bacterium Lysinibacillus fusiformis and Kolanut husk as a component of cultivation medium. The bacterium was isolated from Kolanut plantation waste soil and screened for the production of xylanase qualitatively on xylan nutrient agar and quantitatively under submerged fermentation. The different conditions optimized included substrate concentration, additional sugars, incubation period, temperature, initial pH, nitrogen supplementation and inoculum mass through one factor at a time approach. Maximum xylanase production was obtained at substrate concentration of (1 % xylan and 1.5 % Kolanut husk), nitrogen source (yeast extract plus peptone), carbon source (sucrose), incubation period (24 h), pH (5.0), temperature (35 oC) and inoculum size (1 %). Lysinibacillus fusiformis has been proven to be a promising bacterium for xylanase production using Kolanut husk as substrate. The use of Kolanut husk as foremost carbon source is predominantly precious as being an agricultural waste, affordable, and locally available compared to expensive commercially sold xylan.

Isolation and optimization of extracellular PHB depolymerase producer Aeromonas caviae Kuk1-(34) for sustainable solid waste management of biodegradable polymers

Bioplastics, synthesized by several microbes, accumulates inside cells under stress conditions as a storage material. Several microbial enzymes play a crucial role in their degradation. This research was carried to test the biodegradability of poly-β-hydroxybutyrate (PHB) utilizing PHB depolymerase, produced by bacteria isolated from sewage waste soil samples. Potent PHB degrader was screened based on the highest zone of hydrolysis followed by PHB depolymerase activity. Soil burial method was employed to check their degradation ability at different incubation periods of 15, 30, and 45 days at 37±2°C, pH 7.0 at 60% moisture with 1% microbial inoculum of Aeromonas caviae Kuk1-(34) (MN414252). Without optimized conditions, 85.76% of the total weight of the PHB film was degraded after 45 days. This degradation was confirmed with Fourier-transform infrared spectroscopy (FTIR) and Scanning electron microscope (SEM) analysis. The presence of bacterial colonies on the surface of the degraded film, along with crest, holes, surface erosion, and roughness, were visible. Media optimization was carried out in statistical mode using Plackett Burman (PB) and Central Composite Design (CCD) of Response Surface Methodology (RSM) by considering ten different factors. Analysis of Variance (ANOVA), Pareto chart, response surface plots, and F-value of 3.82 implies that the above statistical model was significant. The best production of PHB depolymerase enzyme (14.98 U/mL) was observed when strain Kuk1-(34) was grown in a media containing 0.1% PHB, K2HPO4 (1.6 gm/L) at 27 ℃ for seven days. Exploiting these statistically optimized conditions, the culture was found to be a suitable candidate for the management of solid waste, where 94.4% of the total weight of the PHB film was degraded after 45 days of incubation.

Isolation, Screening and Morphological characterization of Laccase producing fungi

Research was carried out on the production of extracellular laccase enzyme by fungi isolated from different lignocellulolytic waste soils within the Bhilai- Durg region of Chhattisgarh, India. Soil samples were collected from lignocel- lulolytic waste such as flower, citrus peel and paddy straw soil and immediately transported to laboratory for analysis. Fungal colony was isolated by the serial dilution method on potato dextrose agar. A total of 49 fungal cultures were isolated from the soil samples. Isolated fungal culture were screened for pro- duction of laccase enzyme in guaiacol containing potato dextrose agar plate. Laccase producing fungi was morphological identified by Agharkar Research Institute in Pune. The fungal isolates were identified as Scytalidium lignicola, Humicola fuscoatra, Fusarium sp., Paecilomyces sp., Curvularia sp., Fusar- ium sp., Aspergillus niger, Chaetomium sp., Penicillium sp. And Histoplasma capsulatum

Mixing simulation of cohesive particles in a soil mixer

Soil particle mixing is an important research hotspot in the emerging field of waste soil resources. In this study, the discrete element method (DEM) is used to characterize the mixing of cohesive particles in a soil mixer. To verify the mixing effect of this mixer on cohesive materials, the forces between the particles are simulated using a cohesive contact model. The effects of filling level, rotating shaft speed and size, particle cohesion and size on particle dynamics and mixing performance within the mixer are investigated. The mixing process of the particles is analyzed to quantify the mixing performance by using the coordination number (CN), average velocity, contact force network and mixing index. To assess the degree of mixing using the Lacey mixing index, a grid system is used to divide the mixing area so that the mixing index can be calculated. The results show that this mixer is suitable for mixing cohesive particles and that a lower filling level leads to better mixing efficiency. In addition, the mixing efficiency is significantly improved as the speed and size of the rotating shaft in the mixer increased.

Experimental Investigation on the Influencing Factors of Compressive Strength of Foamed Lightweight Material Utilizing Completely Decomposed Granite.

The utilization of construction waste soil to produce foamed concrete together with cement and a foaming agent is a promising method for waste recycling. Completely decomposed granite (CDG), which is widely available in southern China, was selected as a typical construction waste soil in foamed material production. The Taguchi method was applied to study the influence of various parameters on compressive strength, including cement dosage, CDG dosage, water to solid materials ratio (W/M), fine particles content, and gravel particles content. Analysis of variance (ANOVA) on a CDG-based sample showed that all factors have significant effects on compressive strength and the most effective parameter was cement dosage, followed in sequence by CDG dosage, W/M, gravel particles content, and fine particles content. However, only cement dosage and W/M influence the internal structure significantly during water/vacuum-immersion tests. The relationship between micro-pore structure and compressive strength suggested that with the decrease of open porosity, the compressive strength showed an increasing trend. This study reveals the possibility of CDG as a raw material for foamed lightweight soil and provides a technical reference of production procedure.

Isolation and characterization of keratinolytic bacteria from poultry waste soils of Himachal Pradesh

Isolation and screening of keratinolytic bacteria from the poultry feather dumped soil of ICAR-NEH region, Imphal centreHanjabam Joykishan Sharma, Amanda Nongthombam, Mrinalini Khuraijam, Yaiphaba Laishram

Physical and Mechanical Properties of Cemented Soil Fill At Liquid and Hardened States

Cemented soil fill is a new backfilling technology developed for the problems of narrow foundation trenches and uncompacted backfilling. It has good fluidity before solidification and higher strength and stiffness after solidification. This type of fill materials makes full use of the waste soils. The proportioning test was carried out on excavated soil on a construction site. Liquid property tests and unconfined compressive strength tests was carried out. The results show that the cemented soil fill can meet the requirement of foundation trenches backfilling, which has great prospect for future applications.

Isolation, screening, and molecular identification of pectinase producers from fruits, vegetables, and soil samples

Background and objective In this work, isolation, identification (morphological and chemical), and molecular characterization were done of local isolates of some pectinase-producing microorganisms such as bacteria, actinomycetes, fungi, and yeast.Materials and methods A total of 22 local bacterial isolates were obtained from various sources and were assayed for pectinolytic activity after optimization of conditions for pectinase production. Isolate no. 19 showed the highest pectinase-specific activity (6.73 U/ml) on glucose-supplemented medium, whereas isolate no. 5 gave the lowest pectinase productivity (3.21 U/ml). The identification of isolate no. 19 revealed that it belonged to the genus Bacillus based on morphological and biochemical characteristics. Based on molecular identification (16 S rRNA technique), isolate no. 19 was named Bacillus sp. strain NRBANKI-4 (with 99% similarity), with Gene Bank accession number OM540351.Results and conclusion A total of 14 local actinomycete isolates were obtained from soil samples. Isolate no. 13 showed the highest pectinase-specific activity (6.48 U/ml), whereas sample no. 10 gave the lowest pectinase-specific activity (3.07 U/ml). Based on molecular identification (16 S rRNA technique), isolate no. 13 was named Streptomyces sp. KP 12 (90.63% similarity), with Gene Bank accession number OM403596. A total of 10 fungal isolates were obtained from crop waste soil. Isolate no. 2 gave the highest pectinase productivity (21.20 U/ml). Based on molecular identification (internal transcribed spacer-PCR technique), isolate no. 2 was named Aspergillus niger F8121 (99.47% similarity), with Gene Bank accession number OM392061. Following the same trend, 10 yeast isolates were isolated from crop waste soil. The isolate that gave the highest pectinase productivity was no. 7, which gave 22.03 U/ml. The isolate that gave the lowest was no. 9 (20.74 U/ml). Isolate no. 7 was named Pichia barkeri Y1 (90.91% similarity), with Gene Bank accession number OM392066.

Biodegradation of LDPE plastic by local strain of Bacillus sp. isolated from dump soil of Pekanbaru, Indonesia

Abstract. Fibriarti BL, Feliatra, Amin B, Darwis. 2021. Biodegradation of LDPE plastic by local strain of Bacillus sp. isolated from Dump Soil Pekanbaru, Indonesia. Biodiversitas 22: 5484-5490. Plastic is a compound resistant to degradation and takes tens to hundreds of years to decompose completely. The diversity of microbial metabolism allows microbes to degrade plastic and utilize it as a source of energy and carbon for growth. One type of plastic widely used in packaging is LDPE (Low-Density Polyethylene). The purpose of this study was to test the ability of local isolates of Bacillus sp. strains BP4 and BP6 isolated from waste soil and to identify them at molecular level. In LDPE plastic degradation test, pieces of LDPE plastic were added as a carbon source to a mineral solution medium and incubated for 30 days on shaker incubator at 150 rpm. The percentage of plastic degradation was calculated by subtracting the percentage of the initial weight of the plastic with the final weight. The test results showed that two isolates i.e. BP4 and BP6 were able to degrade LDPE plastics with degradation percentages of 7.23 ± 0.64% and 8.19 ± 0.12%, respectively. Molecular identification results revealed that Bacillus sp. strain BP4 showed a similarity of 99.72% with Bacillus anthracis strain X11, while Bacillus sp. strain BP6 showed a similarity of 99.93% with Bacillus paramycoides strain 8929.

Succession of Microbial Communities in Waste Soils of an Iron Mine in Eastern China

The reclamation of mine dump is largely centered on the role played by microorganisms. However, the succession of microbial community structure and function in ecological restoration of the mine soils is still poorly understood. In this study, soil samples with different stacking time were collected from the dump of an iron mine in China and the physicochemical characteristics and microbial communities of these samples were comparatively investigated. The results showed that the fresh bare samples had the lowest pH, highest ion concentration, and were the most deficient in nutrients while the acidity and ion concentration of old bare samples decreased significantly, and the nutritional conditions improved remarkably. Vegetated samples had the weakest acidity, lowest ion concentration, and the highest nutrient concentration. In the fresh mine soils, the iron/sulfur-oxidizers such as Acidiferrobacter and Sulfobacillus were dominant, resulting in the strongest acidity. Bacteria from genera Acidibacter, Metallibacterium, and phyla Cyanobacteria, WPS-2 were abundant in the old bare samples, which contributed to the pH increase and TOC accumulation respectively. Acidobacteriota predominated in the vegetated samples and promoted nutrient enrichment and plant growth significantly. The microbial diversity and evenness of the three types of soils increased gradually, with more complex microbial networks, suggesting that the microbial community became more mature with time and microorganisms co-evolved with the mine soils.

Design of an Impact Absorbing Composite Panel from Denim Wastes and Acrylated Epoxidized Soybean Oil based Epoxy Resins

The focus of this work is to make a significant contribution to solid waste management by designing impact-absorbing bio-composite panels using bio-resin and denim wastes. In this context, composite panels are produced by vacuum infusion technique using both epoxy and acrylated epoxidized soybean oil (AESO) based hybrid resins while denim wastes are utilized as reinforcement materials in fiber and fabric forms. Both physical (fiber density and fiber weight ratio) and mechanical analyses (drop-weight impact resistance and dynamic mechanical analysis (DMA)) of the composites are performed. The outcomes of the study prove that the increase in the AESO ratio of the resin system improves the ductility of the composite and consequently the impact resistance. On the other hand, dynamic mechanical analysis results indicate that the AESO plug-in reduces the storage module and increases the damping factor.

Stablization of Clayey Soil Via Lime and Plastic Fibre for Advanced Foundation Proposition.

Abstract: Soil is the most widely used and basic material for civil engineering. The soil is used for houses, walls, bridges and roads. The Earth provides various types of soil and varies in its properties, scale, composition and textures. The earth's soil is a natural fine grain rock that contains one or more minerals from Earth, which have metal oxides and traces of organic matter. Based on the structure, the clay has quite a range of characteristics. It's slow, and difficult to accelerate, and used for something small. This study is aimed at achieving soil engineering properties for subgrade. In the subgrade construction, waste plastic bottles are used from waste disposal and the application of raw waste soil reinforcement materials and tried to stabilize the clay soil in different strong lime percentages (2 percent, 4 percent, 6 percent, 8 percent, 10 percent, and 12 percent). Testing of the strength of the clay earth, like Maximum Dry Density (MDD) and California Bearing (CBR) was done at different plastic strip percentages. In order to measure improvements in technologies, the clay floor swelling index and the microscopic examination also are performed. Keywords: Clay soil, Lime, Plastic, fiber material.