Landfill Soil Research Articles

Evaluation of thermostable endoglucanase in Paenibacillus lautus strain BHU3 for yield enhancement

In the present study, Paenibacillus lautus strain BHU3 isolated from landfill soil was evaluated for the presence of potential endoglucanases which are the first candidate of cellulase enzyme system to act on cellulose. In-silico analysis revealed high potential thermostable endoglucanases which can efficiently interact with cellulose. The most potent and thermostable endoglucanase (locus tag id. CPZ30_18280) belonged to glycosyl family-5 and had interaction energy of − 12.981 kcal/mol for the best docked cluster containing three out of ten docking conformations, and Tm value of 73.3 °C. MD simulation of 100 ns proved highly stable binding interactions of CPZ30_18280 endoglucanase with cellulose with root mean square deviation (RMSD) values ranging from 0.15 to 0.30 nm. Consistent interactions with characteristic active site residues (tyrosine, tryptophan and aspartate) of glycosyl family-5 endoglucanases were found. Further, to enhance the production of endoglucanases, the fermentation conditions were optimized employing approaches like one factor at a time (OFAT) and response surface methodology (RSM). Maximum activity of endoglucanase was determined at 60 °C. The optimized conditions for enhanced production of endoglucanase (10.15 U/mL) were pH 6.63, yeast extract conc. 3.44 g/L, wheat bran 3.59%, and inoculum size 2.65%. Hence, P. lautus strain BHU3 has enormous potential to synthesize highly efficient thermostable endoglucanases under optimized regime using agro-wastes. Thus, it could find immense industrial applications including large scale cellulose conversion to bioethanol.

IMPACT OF POLLUTANTS IN THE SOIL OF THE AGROLANDSCAPE OF THE RECULTIVATED LANDFILL ON CROPS

After recultivation of municipal solid waste (MSW) landfills using sewage sludge, such landfills should become environmentally sustainable and productive agricultural landscapes. Sewage sludge significantly impacts the productivity of the newly created agricultural landscape and the quality of agricultural products when creating the arable layer of the recultivated MSW landfill. The research aims to study and analyze the influence of heavy metals and arsenic in the soil of the recultivated landfill on the yield and quality of agricultural products.
 Perennial grasses on the reclaimed landfill are forced to adapt to adverse environmental conditions, which leads to a loss of plant resistance. The research was required due to the presence of heavy metals and other pollutants in the soil, which negatively impact agricultural products and their quality and are also associated with a wide range of physiological and biochemical changes in plants.
 The results of the chemical analysis of Triticosecale, Bromus inermis Leyss, and Festulolium showed low levels of mercury, cadmium, lead, arsenic, copper, and zinc, as well as their suitability for feed. Physico-chemical analysis showed that the most significant amount of crude protein (27.5 g/kg) from the studied samples is contained in Bromus inermis Leyss, crude fiber – in Triticosecale (Option 3) (35.04 g/kg), crude ash – in Festulolium (Option 3) (11.7 g/kg).

Paenalcaligenes niemegkensis sp. nov., a novel species of the family Alcaligenaceae isolated from plastic waste.

Strain NGK35T is a motile, Gram-stain-negative, rod-shaped (1.0-2.1 µm long and 0.6-0.8 µm wide), aerobic bacterium that was isolated from plastic-polluted landfill soil. The strain grew at temperatures between 6 and 37 °C (optimum, 28 °C), in 0-10 % NaCl (optimum, 1 %) and at pH 6.0-9.5 (optimum, pH 7.5-8.5). It was positive for cytochrome c oxidase, catalase as well as H2S production, and hydrolysed casein and urea. It used a variety of different carbon sources including citrate, lactate and pyruvate. The predominant membrane fatty acids were C16 : 1 cis9 and C16 : 0, followed by C17 : 0 cyclo and C18 : 1 cis11. The major polar lipids were phosphatidylglycerol and phosphatidylethanolamine, followed by diphosphatidyglycerol. The only quinone was ubiquinone Q-8. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain NGK35T belongs to the genus Paenalcaligenes (family Alcaligenaceae), appearing most closely related to Paenalcaligenes hominis CCUG 53761AT (96.90 %) and Paenalcaligenes suwonensis ABC02-12T (96.94 %). The genomic DNA G+C content of strain NGK35T was 52.1 mol %. Genome-based calculations (genome-to-genome distance, average nucleotide identity and DNA G+C content) clearly indicated that the isolate represents a novel species within the genus Paenalcaligenes. Based on phenotypic and molecular characterization, strain NGK35T can clearly be differentiated from its phylogenetic neighbours establishing a novel species, for which the name Paenalcaligenes niemegkensis sp. nov. is proposed. The type strain is NGK35T (=DSM 113270T=NCCB 100854T).

Degradation Behavior of Biodegradable Plastics in Thermophilic Landfill Soil and Wastewater Sludge Conditions

In this study, three common biodegradable plastics, namely, poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV), poly(butylene succinate) (PBS) and poly(butylene adipate-co-terephthalate) (PBAT) were all buried in a mixture of landfill soil and wastewater sludge and incubated under thermophilic (61°C) oxygen-limited conditions. At the end of the 90-day test, the degradation ranking order was PHBV > PBS > PBAT. Only PHBV was completely degraded over the 60 days, while PBS and PBAT displayed 24.04% ± 3.37% and 18.26% ± 3.77% weight loss, respectively. The differences in the degradation and disintegration profiles among these materials were observed. The results showed that PHBV lost its thickness and degraded from the edges of the specimens. Both PBS and PBAT were reduced into small fragile fragments during the degradation process. SEM micrographs revealed that irregular roughness with many holes and cracks was characteristic of PHBV, while slightly smooth surfaces were found on PBS and PBAT. All the materials showed continuous decreases in the thermal stability and the percentage of carbon content in the molecular structures after the degradation test. Fourier transform infrared (FTIR) spectroscopy revealed that the chemical structure of PHBV was changed during the biodegradation test, while both PBS and PBAT were unchanged under the same test conditions. However, the peak for carboxylate ions was found after the degradation of all the samples. Having a deep understanding of the degradability behavior can contribute to the development of biodegradable plastic waste management in the future.

Methane Oxidation and Microbial Community Dynamics in Activated Biochar-Amended Landfill Soil Cover

Methane Oxidation and Microbial Community Dynamics in Activated Biochar-Amended Landfill Soil Cover

Ability of Urtica dioica L. to adsorb heavy metals (Pb, Cd, As, and Ni) from contaminated soils

ABSTRACT Landfill leachate contains heavy metals that contaminate water and soil near the landfill site. Phytoremediation is a process of decontaminating soil or water by using native plants to adsorb and accumulate or break down pollutants. This study aimed to evaluate absorption and accumulation of heavy metals from simulated landfill soil by nettle. Nettle seeds were collected from the Tonekabon landfill site and planted in 243 pots. After reaching the 6-leaf stage, the plants were exposed to three concentrations of four heavy metals (Pb, Cd, As, and Ni) during the growing season. An atomic absorption spectrometer was used to measure the concentrations of the heavy metals in nettle plants and the morphological features of nettle fibers. The results showed that increases in the concentrations of the heavy metals in the soils led to their higher concentrations in all organs of the nettle plants (Pb> Ni> Cd> Ar), and larger quantities of the heavy metals were accumulated in the aerial parts of the plants. In parallel with this result, the dry weights of stem, leaf and root, and leaf area index also decreased. Values of TF> 1 and BAC <1 in plant organs showed the ability of nettle to accumulate more heavy metals when they were present at higher concentrations in the soil. Bioremediation using native plants for removal of heavy metals from soil and their accumulation in these plants is a low-cost and environmentally friendly technology. Nettle is a plant that grows wild in the landfills in northern Iran and, due to its ability to accumulative heavy metals in its organs, is a suitable plant species for their removal from soil.

Analysis of Potential Utilization of Landfill Materials (Case Study: Sumur Batu Landfill, Bekasi)

One of the efforts to overcome the critical problem of land usage for landfill and regenerate waste is to reuse the expired landfill after managing them. The purpose of this study is to determine the potential utilization of waste from landfill mining activities. At 15 sample depth points in zone 1 of Sumur Batu Landfill from 2004-2007 waste, the composition of mining landfill waste consists of 29% soil/organic fraction; 25% other waste; 23% plastic; 11% overburden; 5% diaper waste; 2% cloth; 2% wood; 1% glass; 1% rubber; and 1% metal. The particle size of the landfill waste has a diameter distribution of >38.1 mm to <2mm which is almost evenly distributed with values ranging from 9-20%. The calorific value of combustible waste is 3, 569.47 kcal/kg. The chemical characteristics of the landfill soil mining fraction consisted of C-Organic 29.55%, NTK 0.65%, C/N 29.59, and Total-P 22.84%. Dosage variation of landfill mining soil fraction as a planting medium with soil used for research, respectively 1:4, 1:5, and 1:6, and soil with Bokham compost as control. The use of landfill soil fraction as a planting medium with 3 types of soil, namely clay, laterite, and acid clay causes a decrease in the growth of mung beans (Vignaradiata L.). However, the 1:4 landfill soil fraction dose gave a positive response to the physiological observations of plants compared to the other two doses of variation. The potential for landfill waste is 100, 000 tons, the total cost of landfill mining activities is Rp. 25, 829, 996, 775, and the total benefits of landfill mining activities are Rp.26, 347, 223, 544, with the use of combustible waste to produce electricity and/or heat using an incinerator, the benefit ratio value is 1.02 which is means that the activities of the Zone 1 of Sumur Batu Landfill is feasible to carry out. Based on these data, with organic waste as the dominant waste in the Sumur Batu Landfill, the best possibility in utilizing waste is to use the waste as soil fertilizer.

ASSESSMENT OF ECOLOGICAL DANGER OF SEEPAGE WATER SOLID WASTE LANDFILL OF KOKSHETAU

The impact of landfills on the environment is not limited to the dumping of garbage, since the pos-sible penetration of leakage through the subsoil can lead to contamination of groundwater. The study (2021) presents the results of studying the elemental composition of filtration waters and soil of the solid waste landfill in Kokshetau, the period of operation of which at the time of the study was 50 years.Analysis of filtrate samples obtained from landfills showed that the filtrate is a highly concentrated solution containing toxic components. The chemical composition of the filtrate, developed by a gener-ally accepted method from surface aggregation, showed a high content of organic matter and a BOC5 / COC ratio of about 0.01-0.005, which indicates a high content of bioresistant components. It is a liquid from black to yellow-brown in color with a specific odor and a slightly alkaline reaction of the medium (pH = 7.5-8.25). The concentration of heavy metals does not exceed the maximum permissible con-centration for water. The pH value, ammonia ions, high mineralization and concentration of chloride ions are the characteristics of the garbage filter at the operational stage. Normalization of soil quality by chemical indicators showed that at sampling points at a distance of 500 and 1000 m from the landfill corresponds to a dangerous level of pollution, and at a greater distance decreases, these soils belong to the second level of pollution. According to the composition of the filtrate, the landfill belongs to the old landfills.Key words: municipal solid waste, filtration water, environmental impact, pollutants, toxic sub-stances.

Hydraulic conductivity predictive model of RHA-ameliorated laterite for solving landfill liner leachate, soil and water contamination and carbon emission problems

AbstractThe environment is seriously being affected by the leachate release at the unconstructed and badly constructed waste containment or landfill facilities around the globe. The worst hit is the developing world where there is little or totally no waste management system and facilities to receive waste released into the atmosphere. This research work is focused on the leachate drain into the soil and the underground water from landfills, which toxicifies both the soil and the water. Also, the construction of the liner or barrier with cement poses serious threat to the environment due to oxides of carbon release and this research also took this into account by replacing the utilization of cement with rice husk ash (RHA), which has proven to have the potentials of replacing cement as a supplementary binder. Laboratory tests were conducted to determine the hydraulic conductivity (K) of lateritic soil (LS) ameliorated with different dosages of RHA. Other hydromechanical properties of the treated blend were studied and multiple data were generated for the artificial neural network (ANN) back-propagation (-BP), genetic algorithm (GA) and gradual reducing gradient (GRG), genetic programming (GP) and evolutionary polynomial regression (EPR) prediction exercises. Results show that the LS was a poorly graded A-2 sandy silt soil, which was subjected to three different compaction energies with the minimum of the British standard light (BSL) and derived k of 6.95E-10, 50.75E-10 and 32.33E-10 for BSL, west African standard and British standard heavy, respectively. The RHA addition improved the studied properties of the ameliorated LS. Out of the five models, the ANN-GRG outclassed others with a performance of 99% with minimal error compared with the rest. Potentially, this research has shown that RHA with a pozzolanic chemical moduli of 81.47% can replace cement in the construction of ecofriendly and more efficient landfills and waste containemnt barriers to save the soil and the underground water as well as the environment from leachate contamination and carbon emissions.

Biodegradation of low density polyethylene (LDPE) by mesophilic fungus ‘Penicillium citrinum’ isolated from soils of plastic waste dump yard, Bhopal, India

ABSTRACT Low density Polyethylene (LDPE) in various forms has become a part of life. Its accretion due to non degradable nature is concern, endangering life on earth. Amongst various methods of LDPE disposal bioremediation is regarded as ecofriendly & widely accepted. Current investigation was an attempt to isolate potent PE degrading fungus from municipal landfill soils of Bhopal, India loaded with plastic waste.16 fungal isolates were recorded from the site; PE deteriorating fungus was screened using mineral salt agar medium amended with 3% LDPE powder as sole carbon source. The isolate Penicillium citrinum showed fast fungal colony growth in screening medium was selected for biodegradation study. P.citrinum showed 38.82 ± 1.08% weight loss of untreated LDPE pieces; to improve the degradation capacity nitric acid pretreatment was performed; biodegradation was significantly stimulated by 47.22 ± 2.04% after it’s pretreatment. Laccase, lipase, esterase & manganese peroxidase activities were assayed by spectrophotometer. LDPE biodegradation was analyzed by weight loss %, change in pH during fungal growth, field emission scanning electron microscopy (FE-SEM), fourier transform infrared spectroscopy (FTIR) & thermogravimetric analysis (TGA). FTIR spectra showed appearance of new functional groups assigned to hydrocarbon biodegradation, confirming enzymatic role in process. Changes in FTIR spectra of LDPE samples (untreated & pretreated) before & after biodegradation & surface changes in the biodegraded LDPE (indicated from FE-SEM) confirmed depolymerization of LDPE. Further changes in thermal decomposition rates of biodegraded samples in comparison to control, validate biodegradation. This is the first report signifying high competence of P.citrinum in LDPE degradation without prior pretreatment.

Comparative analytical study of landfill soil and soil from sanitary protection zone of the solid municipal waste landfill of the Irkutsk city for 2014 and 2019

The largest SMW landfill in the Irkutsk region is that in the Irkutsk city. In 2014, high heavy metal contents were registered in landfill soil samples taken at the landfill site, and it was proposed to perform monitoring outside the landfill in 2019 and determine the pollution distribution area. In this article, the comparative analysis of the degree of heavy metal pollution of the landfill soil and soil from sanitary protection zone is presented. It was established that the studied landfill soil refers to extremely hazardous soils with heavy metal contents that are up to 68 times higher than TLV. Soil samples from the landfill-affected area also contain heavy metals in high concentrations. The manufacturing supervision of the SMW landfill should include the continuous observation of the soil, water, and air condition in the zone of possible impact of the landfill for taking timely environmental protection measures and preventing further negative impact of the landfill on the ecosystem.

Impacts of sewage sludges deposition on agricultural soils: Effects upon model soil organisms

During years sewage sludges have been worldwide poured in agricultural soils to enhance vegetal production. The “Landfill 17” located in Gernika-Lumo town (43°19′28.9”N 2°40′30.9”W) received for decades sewage sludges from the local Waste Water Treatment Plant (WWTP) with agricultural purposes. To this WWTP, several pollutants as heavy metals (Cd, Cr, Ni, Pb), PAHs (benzo(a)pyrene among many others) and pesticides (i.e. dieldrin) could have arrived from local industry and be widespread all over the landfill. Soil invertebrates like earthworms and plants are of special interest due to their close contact with the polluted matrix and their potential effects by the presence of pollutants. In this context, the aim of the present work was to determine the health status of landfill soils by evaluating the effects on model soil organisms exerted by long-lasted pollutants after on site deposition of WWTP active sludges. With such a purpose, different standard toxicity tests and cellular level endpoints were performed on lettuce and earthworms. Indeed, germination (EPA 850.4100) and root elongation (EPA 850.4230) tests were carried out in Lactuca sativa, while OECD acute toxicity test (OECD-204), reproduction test (OECD-222) and Calcein-AM viability test with coelomocytes were applied in Eisenia fetida worms. For the exposure, soils collected in the landfield containing low, medium and high concentrations of pollutants were selected, and as reference LUFA 2.3 natural standard soil was chosen. While no differences were shown in the assays with L. sativa, significant differences between sludge exposed groups and control group were recorded with E. fetida, with lower coelomocyte number and viability and higher tissue metal accumulation after 28 days of exposure to polluted soils. These results confirmed the impact of contaminants to soil biota even after long periods of time.

Degradation profile and dioxygenase activity of Carnobacterium gallinarum (mt350233) and Enterococcus faecalis (mt345788) isolated from landfill soil in Benin City

Landfill is a potential microbial hub of hydrocarbon (HC) degrading bacterial population owing to nutrient availability and continuous enrichment by organic materials. The degradation and dioxygenase activity of Carnobacterium gallinarum and Enterococcus faecalis isolated from landfill soil in Benin City was investigated. Soil samples were collected from a Government approved landfill in Benin City at a depth of 0 to 10 cm. Standard microbiological and molecular methods were followed for the isolation and characterization of bacterial population. Bacterial isolates were standardized for degradation using spectrophotometer optical density (OD) 0.08 at 600 nm (equivalent to 1×108cfu/ml). The gas chromatography with flame ionization detector (GC-FID) method was used to determine the total petroleum hydrocarbon (TPH) of waste engine oil (WEO) containing samples. The spectrophotometric methods were used for the assay of catechol 1,2-dioxygenase (C12O) and catechol 2,3-dioxygenase (C23O) activity. The result of the 16S rRNA analyses of the bacterial isolates confirmed the identity of Carnobacterium gallinarum as 98.71 % and Enterococcus faecalis as 100 %. The degradation profile of Carnobacterium gallinarum and Enterococcus faecalis at varied concentrations (20, 40, 60, 80 and 100 mg/L) of WEO showed significant decline in optical density (OD) values from day 1 to day 7. The decline in OD is an indication of utilization of Polycyclic Aromatic Hydrocarbons (PAHs) present in the WEO. The result of the gas Chromatography with Flame Ionization Detector (GC-FID analyses) of degraded WEO containing samples revealed the absence of low molecular weight and high molecular weight PAHs after the 7-days degradation study. The presence of HC degrading enzyme in the bacterial isolates was confirmed by the production of C12O and C23O as a result of the formation of cis, cis muconic acid and 2-hydroxymuconic semi-aldehyde respectively. This study revealed that the landfill soil is a potential natural microcosm for WEO degrading bacteria and possesses biologically active HC degrading bacteria population such as Carnobacterium gallinarum and Enterococcus faecalis.

An appraisal of Heavy Metal Concentration in Soil and Selected Subterranean Animals in Olusosun Landfill, Ojota, Lagos State

As a result of the global industrial activities, contamination of the ecosystem by heavy metals has given rise to one of the most important ecological and organismic challenges. An experimental study was performed to ascertain the levels of heavy metals in soil and selected subterranean animals in dumpsites in Lagos State. One (1) kg each of four composite soil samples at a depth of 0 -15cm from the soil surface within the landfill were collected using an auger. The level of parameters such as soil pH, temperature and soil moisture content were determined. Earthworm, Maggot and Spider from each sampled soil were washed in distill water to remove soil particles. The heavy metals (Zn, Cd, Cr, Cu and Pb) were then analyzed by Atomic Absorption Spectrophotometry (AAS). The result of the study showed that Pb and Cd had higher mean concentration (0.75mg/kg and 0.1mg/kg respectively) for the landfill soil sample compared to the control soil sample and subterranean animals. The result also showed that Maggot and Earthworm had higher means concentration of Zn (0.31mg/kg and 0.14mg/kg respectively) compared to the soil samples (landfill and control) and spider. The result was not statistically significant comparing the mean concentration of heavy metals on the landfill soil and the subterranean animals. Chromium (Cr) was not detected in the study. The study concluded that there is high anthropogenic influence and persistence of the heavy metals which accumulated in the environment and pose serious ecological and health challenges.

КАЧЕСТВЕННЫЕ И КОЛИЧЕСТВЕННЫЕ ХАРАКТЕРИСТИКИ ПОЧВ И СВАЛОЧНОГО ГРУНТА ПОЛИГОНА ТВЕРДЫХ КОММУНАЛЬНЫХ ОТХОДОВ

The largest SMW landfill in the Irkutsk region is that in the Irkutsk city. In 2014, high heavy metal contents were registered in landfill soil samples taken at the landfill site, and it was proposed to perform monitoring outside the landfill in 2019 and determine the pollution distribution area. In this article, the comparative analysis of the degree of heavy metal pollution of the landfill soil and soil from sanitary protection zone is presented. It was established that the studied landfill soil refers to extremely hazardous soils with heavy metal contents that are up to 68 times higher than TLV. Soil samples from the landfill-affected area also contain heavy metals in high concentrations. The manufacturing supervision of the SMW landfill should include the continuous observation of the soil, water, and air condition in the zone of possible impact of the landfill for taking timely environmental protection measures and preventing further negative impact of the landfill on the ecosystem.

Geotechnical Properties Of Tropical Residual Soils For Sustainable Landfilling

To select a site for sanitary landfilling, it is paramount that geotechnical analysis is conducted to acquire relevant data for the purpose of studying soil properties. One of the basic requirements for the landfill site selection process is geotechnical criteria. This ensures that the chosen sites are founded on an impermeable soil deposit having adequate geotechnical characteristics that is also socially acceptable, economically cheap, and environmentally friendly. Geotechnical properties investigated in the laboratory for three sites samples comprises volumetric shrinkage, shear strength, and permeability. Groundwater contamination comes because of leachate. As such soil meant for landfill sites must have exceptional geotechnical properties able of restraining these leachates. Consequently, landfill soils must possess excellent ability to retain leachate in terms of permeability, an acceptable shear strength to withstand the waste load, and appropriate volumetric shrinkage to refute wetting and drying seasonal variations. The physical properties which showed that site A has a fines content of its soil up to 51%, site B with 29% and site C with 14%. Engineering property showed that site A has the lowest permeability of 2.1 × 10-9 m/s, followed by site B with 2.08 × 10-8 m/s, and then site C with the highest permeability of 1.5 × 10-7 m/s at OMC. The results show that only site A achieved maximum regulatory range of permeability value of 10-9 m/s. This implies that site A is the most suitable and sustainable, then followed by site B and then site C.

The Effect of Demographic Factors on Waste Generation and Heavy Metal in Illegal Landfill at Malaka Regency, East Nusa Tenggara Province

The population growth has led to a significant increase in the amount of waste every year. Meanwhile, several demographic factors influencing waste generation in Malaka Regency include an absence of a final landfill. This has caused the illegal dumping of waste which leads to various environmental problems. Therefore, this study aims to (I) analyze the effect of demographic factors on waste generation (II) determine the level of heavy metals and the chemical properties of the soil in the illegal landfill. In this study, the demographic factor sampling was conducted in all districts using a questionnaire to obtain each household sample and waste was weighed directly with the Stratified Random Sampling method. Also, soil samples at the landfill site were obtained through field observation and composite sampling. The results showed that age, gender of each family head, income, occupation, latest education, and the number of family members had a significant effect on waste generation in Malaka Regency. Based on the results, the content of Pb, Cd, and Hg in the soil at different waste disposal sites in Malaka Regency had passed the standard threshold value in soil, which showed that the land had been polluted by heavy metals.

STABILIZATION OF LIANG ANGGANG SAND WITH FLY ASH AND CEMENT AS SUBGRADE IMPROVEMENT MATERIALS

The more coal production is produced, the more waste is coming from the combustion process which leads to the environmental pollution. Waste from burning coal in the form of fly ash can be used as a mixture of subgrade stability in highway construction. The purpose of this study is to determine the characteristic value of each combination of fly ash, Liang Anggang sand and cement as a mixture of subgrade layer materials. The test objects consist of 10 combinations of fly ash, Liang Anggang sand and cement. Some tests were conducted such as Atterberg Limits, Specific Gravity, Sieve Analysis, Compaction and CBR test, respectively. From all combinations of the test objects, the best combination that suits the characteristic values of a subgrade layer mixture is a combination of minimum 6% of CBR specification and a maximum of 6% of Plasticity Index (PI). The recommended economical combination for landfill soil is a combination of test objects with a composition of 75% fly ash, 20% Liang Anggang sand and 5% cements.

Distribution and Characterization of Heavy Metal and Pollution Indices in Landfill Soil for Its Rehabilitation by Phytoremediation

Population growth associated with urban development in African cities is a key environmental concern in development programs. Indeed, urban areas are strongly impacted by the production of municipal waste, the management of which remains problematic and is only stored in open dumps. This is the case in the city of Bonoua, a small town located 59 km east of Abidjan in the South Comoé region of Côte d’Ivoire. The management of municipal waste in this town is crucial because all the mineral water sources are concentrated in this town. The objective of this study is to characterize and map the distribution of trace metal elements in the largest urban landfill in the city in order to propose an efficient strategy for rehabilitation into an urban park. Soil samples were collected from the entire site (landfill and surrounding soil) and from a control site. The total content of trace metals (Pb, Cd, Cr, and Zn) in the soil was analyzed by X-ray fluorescence spectrometry (XRF). Soil pollution was evaluated through enrichment factors, geoaccumulation indices and pollution indices. The results show that the calculated geoaccumulation indices and their distribution maps indicate a pollution of the site in these elements. The values of the PI higher than the unit reveal a pollution of the site in several elements. The levels of Pb, Cd, Cr and Zn are higher than the levels in the upper continental crust and in the control soil. The spatial distribution shows a significant accumulation of Pb, Cr and Zn on the landfill while Cd is concentrated in the surrounding soils. The calculated enrichment factors suggest an anthropogenic origin of the heavy metal at the study site. These results indicate polymetallic pollution by metals that can persist in the environment and affect human health.

Influence of Fly Ash-Based Geopolymers on Treated-Contaminated Soil Properties

Using natural soil in landfill sites for landfill construction is common in developing countries such as Indonesia. However, the risk of contaminated soil being used as material needs to be reduced by soil improvement to meet the landfill base requirement. Geopolymer is one stabilization material with high durability towards the contaminants, in which fly ash is one of the best geopolymer raw materials due to its readily great supplies and noble properties. The present study investigates fly ash-based geopolymer (FAG) influence on the treated-contaminated soil properties specifically for landfill liner purposes. The studied soils were collected from Ngipik Landfill, an indiscriminate municipal landfill in Gresik, East Java-Indonesia. The samples were obtained from three different locations around the waste mound and stabilized with FAG at 5, 10, and 15 wt.% of unstabilized soil at its optimum water content compared to the natural soil. The laboratory-scale tests were conducted, including the unconfined compressive strength test, standard compaction proctor, consolidation test, and the permeability test to understand the treated-soil characteristics better. The Scanning Electron Microscope (SEM) analysis was gathered to examine the treated soil’s micro-properties. The results denoted that the FAG addition increases the soil's compressive strength up to 36% and reduces the compressibility to up to 60%. The permeability shows a slight decrement in 5% and 10% of FAG addition. The SEM image indicates that the FAG made bonds and fills the void. This study concludes the FAG enhances the mechanical properties of Ngipik Landfill soil despite the contamination.