Assessment of respiration activity and ecotoxicity of composts containing biopolymers

Remediation of soils on municipal rendering plant territories using Miscanthus × giganteus

Phytoremediation, as a cost-effective, highly efficient, environmentally friendly, and green approach, gained attention to the removal of metals, including heavy metals, from contaminated soils. The toxic nature of heavy metals can have an adverse effect on human health and the ecosystem, and their removal remains a worldwide problem. Therefore, in this study, a field experiment was carried out to evaluate the potential of Miscanthus × giganteus for the removal of ten microelements and heavy metals (Al, Zn, Fe, Pb, Cd, Co, Cr, Cu, Mn, Ni) from contaminated soil in the territory of a Municipal Waste Rendering Plant. Moreover, the effect of the incorporation of soil improver obtained upon composting biodegradable waste as well as the addition of highly contaminated post-industrial soil on the efficiency of phytoremediation and plant growth was described. The soil improver (SK-8) was applied to the soil at a rate of 200 Mg ha^-1 and 400 Mg‧ha^-1. Meanwhile, in the last object, 100 Mg‧ha^-1 of highly contaminated post-industrial soil was added. Herein, the research was aimed at assessing the possibility of phytoextraction of heavy metals from soils with different physicochemical properties. The results showed that plants cultivated in soil with 400 Mg‧ha^-1 of soil improver exhibited the highest yield (approximately 85% mass increase compared to the soil without additives). Furthermore, the application of a single dose of SK-8 (200 Mg ha^-1) increased the uptake of Al, Fe, Co, Pb, Mn, Ni, and Cd by Miscanthus × giganteus compared to the soil without additives. Additionally, the performed biotests demonstrated no or low toxicity of the investigated soils affecting the test organisms. However, in all experiments, the phytorecovery of the elements did not exceed 1% of the amount introduced to the soil, which may result from a short cultivation period and large doses of SK-8 or highly contaminated post-industrial soil.

Strategies and progress in synthetic textile fiber biodegradability

Abstract

The serious issue of textile waste accumulation has raised attention on biodegradability as a possible route to support sustainable consumption of textile fibers. However, synthetic textile fibers that dominate the market, especially poly(ethylene terephthalate) (PET), resist biological degradation, creating environmental and waste management challenges. Because pure natural fibers, like cotton, both perform well for consumer textiles and generally meet certain standardized biodegradability criteria, inspiration from the mechanisms involved in natural biodegradability are leading to new discoveries and developments in biologically accelerated textile waste remediation for both natural and synthetic fibers. The objective of this review is to present a multidisciplinary perspective on the essential bio-chemo-physical requirements for textile materials to undergo biodegradation, taking into consideration the impact of environmental or waste management process conditions on biodegradability outcomes. Strategies and recent progress in enhancing synthetic textile fiber biodegradability are reviewed, with emphasis on performance and biodegradability behavior of poly(lactic acid) (PLA) as an alternative biobased, biodegradable apparel textile fiber, and on biological strategies for addressing PET waste, including industrial enzymatic hydrolysis to generate recyclable monomers. Notably, while pure PET fibers do not biodegrade within the timeline of any standardized conditions, recent developments with process intensification and engineered enzymes show that higher enzymatic recycling efficiency for PET polymer has been achieved compared to cellulosic materials. Furthermore, combined with alternative waste management practices, such as composting, anaerobic digestion and biocatalyzed industrial reprocessing, the development of synthetic/natural fiber blends and other strategies are creating opportunities for new biodegradable and recyclable textile fibers.

Article Highlights

The influences of illite/smectite clay on lignocellulose decomposition and maturation process revealed by metagenomics analysis during cattle manure composting

The purpose of this study was to analyze the effects of illite/smectite clay (I/S) on lignocellulosic degradation and humification process via metagenomics analysis during cattle manure composting. The test group (TG) with 10% I/S and the reference group (RG) were established. The results indicated that the addition of I/S made the degradation rate of cellulose, hemicellulose and lignin in TG (1.56%, 29.01%, 19.95%) was higher than that in RG (1.16%, 17.24%, 13.14%). Compared with RG, the abundance values of AA2, AA10, GH1 and GH10 in TG increased by 15.18%, 29.28%, 31.08%, 21.65%, respectively. Meanwhile, humic substance (HS) content was increased by 3.49% and 7.16% during RG and TG composting. Furthermore, the microbial community in TG changed, in which the relative abundance of Actinobacteria increased and Proteobacteria decreased. Redundancy analysis (RDA) showed that the temperature was positively correlated with the abundance of AA2, AA10, GH1 and GH10, whereas the organic matter content was negatively correlated. Overall, adding I/S to the composting could stimulate microbial activity, promote the degradation of lignocellulose and humification process.

Gasification filter cake reduces the emissions of ammonia and enriches the concentration of phosphorous in Caragana microphylla residue compost

Nutrient loss is a major problem during agricultural waste composting. This study investigated the impact of gasification filter cake (GFC) addition on gaseous emissions and nutrient loss during composting of chicken manure mixed with Caraganna microphylla straw. The GFC was added to the composting mix at dry weight rates of 0% (GFC₀), 6.25% (GFC_6.25), 12.5% (GFC_12.5), 25% (GFC₂₅) and 50% (GFC₅₀). Overall, GFC_12.5 and GFC₂₅ efficiently enhanced organic matter decomposition, reduced N loss and enriched P and K concentrations during composting, as compared to GFC₀. However, GFC_6.25 did not show a significant effect on organic matter decomposition, while GF_C50 had no effect on N loss. As a result, an overall enhancement of nutrient contents was observed in the final composts of GFC_12.5 and GFC₂₅. These results suggest that the addition of GFC at moderate-rates (i.e. 12.5% and 25%) can enhance nutrient retention and thereby result in a nutrient-rich compost.

Ecotoxicological and chemical properties of the rożnów reservoir bottom sediment amended with various waste materials

In the study, an attempt was made to create innovative mixtures based on bottom sediment and various types of waste to be tested for use as a substrate in the cultivation of consumer and non-consumer plants. The aim of the study was to assess the chemical and ecotoxicological properties of the growing medium prepared on the basis of bottom sediment (BS) and different carbon rich waste (cellulose waste (CW), biomass ash (BA), coffee hulls (CH), and sludge from water treatment (SW)) with a combination of 75% bottom sediment and 25% waste material. The mixtures had deacidifying properties, significant content of total organic carbon (TOC), the total quantities of macro- and micronutrients, and good sorption properties. The study showed a low total content of heavy metals in the mixtures. Moreover, a low share of the mobile fraction (F1) of metals indicated a low risk related to the metals mobility and potential bioavailability. The highest toxic effect was found in the mixture of bottom sediment and cellulose waste. Heterocypris incongruens was the most sensitive organism to substances present in the tested mixtures. Due to its low toxicity, the mixture of bottom sediment and water treatment sludge (BS+SW) constituted a potentially suitable substrate for its environmental application in agriculture, horticulture (for consumer crops) or land reclamation. Other mixtures exhibited valuable chemical properties (BS + BA, BS + CH BS + CW), but ended up being eco-toxic to the organisms, excluding them from agricultural or horticultural use for consumer crops. The proposed technology, which includes the production of growing medium based on the use of bottom sediment, is a promising way of transforming the sediment from a waste material to a valuable resource, thus enhancing the environmental benefits.

Effects of amendments of PCB-containing Hudson River sediment on soil quality and biochemical and growth response of cucumber (Cucumis sativus L. cv 'Wisconsin SMR 58')

Approximately 200 million m³ of sediments are dredged every year in the United States. Of this amount, 2.3-9 million m³ are contaminated to the extent that they require special, and often costly, handling. Therefore, there is a pressing need to develop appropriate technology for the safe utilization of these sediments, especially in the case of the Hudson River, which is well known to demonstrate significant polychlorinated biphenyls (PCBs) contamination. Hence, the aim of the present study was to examine the influence of different doses of Hudson River sediments (10%, 25%, 50%, 75% and 100% admixtures) on soil quality and on the biochemical and growth response of cucumber (Cucumis sativus L. cv 'Wisconsin SMR 58'), used as potential phytoremediation tool for sediment-borne PCBs. A sediment/soil admixture was found to significantly decrease the nitrogen (N) content in the substratum; in addition, phosphorus (P) content was significantly increased by 50-100% sediment, while potassium (K) content was significantly increased by 10% sediment, and significantly decreased by >50% sediment. Although sediment treatment resulted in a gradual increase in PCB content in the soil-sediment substratum, exceeding the threshold effect concentration (TEC) for the ≥50% sediment admixture, the Microtox assay did not suggest toxicity to microorganisms. The results demonstrated also that admixture of 10-25% Hudson River sediment increased cucumber growth; however, higher doses led to growth inhibition, manifested as lower biomass and smaller leaves. Also, chlorophyll a and b content decreased with increasing doses of sediment. Phenylpropanoid and flavonol contents were significantly higher in plants grown in soil amended with 10% of sediment, but significantly lower in soil treated with a 100% sediment admixture. The anthocyanin content in plants was lower at admixtures of 50% and higher. The obtained results corresponded with the decreasing content of N and K.

Remediation of pyrene contaminated soil by double dielectric barrier discharge plasma technology: Performance optimization and evaluation

Polycyclic aromatic hydrocarbons (PAHs) in soil are not only detrimental to environment but also to human health. Double dielectric barrier discharge (DDBD) plasma reactor used for the remediation of pyrene contaminated soil was studied. The performance of DDBD reactor was optimized with influential parameters including applied voltage, type of carrier gas, air feeding rate as well as pyrene initial concentration. The analysis of variance (ANOVA) results showed that input energy had a great effect on pyrene remediation efficiency followed by pyrene initial concentration, while, the effect of air feeding rate was insignificant. More specifically, the remediation efficiency of pyrene under air, nitrogen and argon as carrier gas were approximately 79.7, 40.7 and 38.2% respectively. Pyrene remediation efficiency is favored at high level of applied voltages and low level of pyrene initial concentration (10 mgkg^-1) and air feeding rate (0.85 L/min). Moreover, computation of the energy efficiency of the DDBD system disclosed that an optimal applied voltage (35.8 kV) and higher initial pyrene concentration (200 mgkg^-1) favored the high energy efficiency. A regression model predicting pyrene remediation under DDBD plasma condition was developed using the data from a face-centered central composite design (FCCD) experiment. Finally, the residual toxicity analysis depicted that the respiratory activity increased more than 21 times (from 0.04 to 0.849 mg O₂ g^-1) with a pyrene remediation efficiency of 81.1%. The study demonstrated the DDBD plasma technology is a promising method not only for high efficiency of pyrene remediation, but also recovering biological function without changing the physical-chemical properties of soil.

Evaluation of ecotoxicological and chemical properties of soil amended with Hudson River (New York, USA) sediment

The aim of this study was to assess the potential for application of Hudson River sediment as a plant growth medium by mixing with various proportions of soil. The growth medium obtained by the admixture of soil and Hudson River sediment was characterized by optimal pH, reduced salinity, and presence of macro- (K, Mg) and micronutrients (Fe, Mn). Apart from beneficial nutrients and organic matter, the riverine sediment also contained toxic metals (Zn 86 mg; Cu 17.8 mg; Ni 16.6 mg; Cr 20.7 mg; Cd 0.46 mg; Pb 20.7 mg/kg, at concentrations below the threshold effect concentration) and PCBs (total concentration 254 ng/g), which can have a negative impact on soil ecosystems. The results ecological risk assessment of six trace elements and PCBs in sediment suggested medium/moderate risk (PECq = 0.21) and the need for ecotoxicological tests prior to its use as a growth medium. However, ecotoxicity tests of the soil/sediment admixture indicated that it was non-toxic or less-toxic to crustacean Heterocypris incongruens (PE = - 8-38%) and bacteria Aliivibrio fischeri (PE = - 20-38). For Sinapis alba L. and Lepidium sativum L., the germination index (GI) indicated the dominance of inhibitory effect on plant growth; whereas for the Sorghum saccharatum L., the GI value showed the stimulatory effect. Based on the above physicochemical and ecotoxicological analyses, the sediment was found suitable for use as a growth medium, for non-edible plants. It is worth to underline that this sediment was collected from relatively less contaminated location of the river and therefore the results may not represent sediments from entire stretch of the Hudson River.

Biodegradability of woody film produced by solvent volatilisation of Japanese Beech solution

To address the problem of marine pollution from discarded plastics, we developed a highly biodegradable woody film, with almost the same components as wood, from the formic acid solution of ball-milled wood. We found that the woody film was not easily degraded by cultured solution of hand bacteria (phylum Proteobacteria was dominant). However, the film was easily biodegraded when in cultured solution of soil (Firmicutes, especially class Bacilli, was dominant) for 4 weeks at 37 °C, or when buried in the soil itself, both under aerobic conditions (Acidobacteria and Proteobacteria were dominant) for 40 days at room temperature and under anaerobic conditions (Firmicutes, especially family Ruminococcaceae, was dominant) for 5 weeks at 37 °C. Moreover, when film was buried in the soil, more carbon dioxide was generated than from soil alone. Therefore, the film was not only brittle but formed of decomposable organic matter. We showed that the film does not decompose at the time of use when touched by the hand, but it decomposes easily when buried in the soil after use. We suggest that this biodegradable woody film can be used as a sustainable raw material in the future.

A mixture of cellulose production waste with municipal sewage as new material for an ecological management of wastes

Chemical contaminants present in cellulose production waste and municipal sewage sludge condition the necessity to treat these wastes before they are introduced into the environment. Environmental use of the these wastes appears to be justified owing to the content of organic substances as well as the considerable fertilising value. The aim of the study was to assess chemical composition and ecotoxicity of cellulose production waste and municipal sewage sludge in terms of their eco-friendly application. The assessment was done based on the established soil environment according to regulations in Poland. The research on the chemical composition of the wastes was conducted under laboratory conditions, determining the content of macroelements, microelements and heavy metals with respect to using these wastes in the environment. Phytotoxkit and Microtox tests were performed in order to determine the ecotoxicity of the wastes in the aspect of their environmental use. It was established that, compared to the cellulose production waste, the municipal sewage sludge used in the incubation experiment had a higher content of macroelements and microelements. The content of heavy metals in the waste did not exceed the permissible content that conditions their use in agriculture and reclamation. Based on the results of bioassays it was established that the cellulose production waste was toxic, whereas the combination of cellulose production waste and sewage sludge was found to be of low toxicity to test organisms. The applied wastes and their mixtures were ranked according to phytotoxicity in the following order: cellulose production waste > cellulose production waste + soil > cellulose production waste + sewage sludge. The research results indicate that waste mixtures qualify for environmental use. With respect to the variable chemical composition of cellulose production waste and municipal sewage sludge as well as their ecotoxicity, it was established that each batch intended for environmental use must be subjected to chemical analysis and ecotoxicological tests.

Influence of thermoplasticized starch on physical-chemical properties of new biodegradable carriers intended for forest industry

In this work, the influence of different concentrations of thermoplasticized starch on thermal, mechanical, biodegradation and phytotoxic properties of biodegradable blend carrier composed of poly(lactic acid) and poly(butylene adipate‑co‑terephtalate) was investigated. The results showed that the addition of poly(butylene adipate‑co‑terephtalate) increased elasticity of PLA materials, whereas the presence of thermoplasticized starch promoted higher biodegradation rate of the investigated materials. Moreover, the prepared materials did not show phytotoxic effect on plant, thus proving potential application in forest industry as a biodegradable carrier for multiplication of plants.

Influence of clay as additive on greenhouse gases emission and maturity evaluation during chicken manure composting

To assess the impact of clay as additive on compost maturity and reduction of greenhouse gases (GHGs) as well as ammonia emission during chicken manure composting. Six treatments with different dosages of clay (0%, 2%, 4%, 6%, 8% and 10% clay added by dry weight basis of chicken manure and wheat straw) were designed to conduct an aerobic composting experiment for 50 days. The results showed that the clay amendment could prolong the thermophilic phase and reduced the maturity period of composting. In addition, the GHGs (N₂O and CH₄) and ammonia emission of clay added treatments were reduced by 25.3-63.4%, 26.01-50.24% and 8.5-70.5%, respectively. But CO₂ emission was significantly higher in 10% clay amended treatment. Furthermore, the redundancy analysis showed that C/N ratio and total organic matter among all physiochemical properties had significant relationship with GHGs and ammonia emission. Therefore, this study shown that clay addition can promote maturity, reduced GHGs emission and improve the quality of product.

Synergic use of chemical and ecotoxicological tools for evaluating multi-contaminated soils amended with iron oxides-rich materials

Abandoned waste piles from ancient mining activities are potential hot spots for the pollution of the surrounding areas. A pot experiment was carried out to check the potential toxicity of the dumping material present in one of these scenarios, and several amendments were tested to attenuate the spread of the contamination events. The waste material had an acid pH and a large total concentration of As and Cu. A dose-response experiment was performed with this material following OCDE 208 test. A proportion 90:10 uncontaminated soil: dumping material (% w/w) was selected for the following experiment, in order to surpass the amount of dumping material that caused 50% reduction in plant growth. Pots were filled with the 90:10 mixture, planted with seeds of Brassica napus and amended with the following materials: three iron oxides of Bayoxide® E33 series, iron (II) sulphate in combination with de-inking paper sludge (Fe+PS), iron oxide-rich rolling mill scale (ROL) and iron oxide-rich cement waste (CEM). Amendment effectiveness evaluation was based on chemical and biological assays: extractable trace element concentration, soil enzymatic activities, inhibition of light emission of V. fischeri and Anabaena sp., B. napus L. fresh weight and screening test for emergence of B. napus L. seedlings. Amendments E33HCF and Fe+PS were the most effective in reducing extractable As and Zn concentration. B. napus weight and dehydrogenase and β-glucosidase activities were positively increased with the two above mentioned treatments but they triggered more toxic effects for V. fischeri luminescence. E33P treatment was the only in which the EC₅₀ was higher than in the control. Anabaena sp. was less sensitive than V. fischeri as its luminescence was not hampered by any treatment. Trace element concentration did not significantly affect the failure in seed emergence. E33HCF and Fe+PS could act as proper amendments as they decreased extractable As and Zn. Further, plant fresh weight, enzymatic activities and some of the bioassays identified the latter treatments as the best ones among those tested here to this type of multi-contaminated soil.

The effect of low-temperature transformation of mixtures of sewage sludge and plant materials on content, leachability and toxicity of heavy metals

The aim of the study was to determine the influence of the process of low-temperature transformation and the addition of plant material to sewage sludge diversifying the content of mobile forms of heavy metals and their ecotoxicity. The experimental design included: sewage sludge+rape straw, sewage sludge+wheat straw, sewage sludge+sawdust, sewage sludge+bark and sewage sludge with no addition. The mixtures were subjected to thermal transformation in a chamber furnace, under conditions without air. The procedure consisted of two stages: the first stage (130°C for 40 min) focused on drying the material, whereas in the second stage (200°C for 30 min) proper thermal transformation of materials took place. Thermal transformation of the materials, caused an increase in total contents of heavy metals in comparison to the material before transformation. From among elements, the cadmium content changed the most in materials after thermal transformation. As a result of thermal transformation, the content of water soluble form of the heavy metals decreased significantly in all the prepared mixtures. Low toxicity of the extracts from materials for Vibrio fischeri and Lepidium sativum was found in the research, regardless of transformation process. L. sativum showed higher sensitivity to heavy metals occurring in the studied extracts from materials than V. fischeri, evidence of which are the positive significant correlations between the content of metals and the inhibition of root growth of L. sativum.

Chemical properties and toxicity of soils contaminated by mining activity

This research is aimed at assessing the total content and soluble forms of metals (zinc, lead and cadmium) and toxicity of soils subjected to strong human pressure associated with mining of zinc and lead ores. The research area lay in the neighbourhood of the Bolesław Mine and Metallurgical Plant in Bukowno (Poland). The study obtained total cadmium concentration between 0.29 and 51.91 mg, zinc between 7.90 and 3,614 mg, and that of lead between 28.4 and 6844 mg kg(-1) of soil d.m. The solubility of the heavy metals in 1 mol dm(-3) NH4NO3 was 1-49% for zinc, 5-45% for cadmium, and <1-10% for lead. In 1 mol HCl dm(-3), the solubility of the studied metals was much higher and obtained values depending on the collection site, from 45 to 92% for zinc, from 74 to 99%, and from 79 to 99% for lead. The lower solubility of the heavy metals in 1 mol dm(-3) NH4NO3 than 1 mol HCl dm(-3) is connected with that, the ammonium nitrate has low extraction power, and it is used in determining the bioavailable (active) form of heavy metals. Toxicity assessment of the soil samples was performed using two tests, Phytotoxkit and Microtox(®). Germination index values were between 22 and 75% for Sinapis alba, between 28 and 100% for Lepidium sativum, and between 10 and 28% for Sorghum saccharatum. Depending on the studied soil sample, Vibrio fischeri luminescence inhibition was 20-96%. The sensitivity of the test organisms formed the following series: S. saccharatum > S. alba = V. fischeri > L. sativum. Significant positive correlations (p ≤ 0.05) of the total and soluble contents of the metals with luminescence inhibition in V. fischeri and root growth inhibition in S. saccharatum were found. The general trend observed was an increase in metal toxicity measured by the biotest with increasing available metal contents in soils. All the soil samples were classified into toxicity class III, which means that they are toxic and present severe danger. Biotest are a good complement to chemical analyses in the assessment of quality of soils as well as in properly managing them.

Phytotoxkit/Phytotestkit and Microtox® as tools for toxicity assessment of sediments

The aim of the study was to use bioassays to evaluate the toxicity of pore water, sediments and sediments elutriates. Furthermore, a possible relationship between observed toxicity and results of chemical analysis was examined. Sediment (0-10 cm) samples were collected from 21 locations in Zeslawice reservoir, Southern Poland using an Ekman sampler. Toxicity assessment of the sediment and pore water samples was performed using direct-contact tests Phytotoxkit/Phytotestkit and Microtox®. Inhibition of seed germination in the test plants was from -25 to 38 percent for sediment and from 0 to 50 percent for pore water, whereas inhibition of root growth was within a range from -42 to 37 percent for sediment and from -49 to 37 percent for pore water. Depending on the sediments, Vibrio fischeri luminescence inhibition was from -18 to 40 percent for sediments elutriates and from -12 to 28 percent for pore water. The toxicity tests showed a positive correlation between metals and the root growth inhibition in Lepidium sativum and Sinapis alba as well as the luminescence inhibition in V. fischeri. No significant correlations were found between the inhibition of luminescence and the phytotoxicity assays, so these analyses do not show a similar sensitivity to toxicants in the sediments. While estimating the sensitivity of the performed biotests, the highest number of toxic responses was recorded in the Microtox® test towards V. fischeri. Among the plant species, Sorghum saccharatum appears to be the most sensitive plant species. Most of the examined sediment samples (67 percent) were classified as class II (low-toxic samples, low acute hazard) and 33 percent of the examined samples were class I (no essential toxic effect, non-toxic sample, no acute hazard) in terms of toxicity. Most of the pore water samples (71 percent) were also classified as class II.