Degradation of greenhouse twines derived from natural fibers and biodegradable polymer during composting

Characterization of Natural and Synthetic Fabrics for the Treatment of Complex Wastes

In the present study, nine fabrics have been tested for brackish water treatment with the aim of industrial application under the concept of zero liquid discharge (ZLD). Moisture content was determined, where it was observed that the lignocellulosic fabrics had a moisture content ranging from 2.5 to 8.5%. The wetting contact angle showed that the flax with polylactic acid (LPLA) was the most hydrophobic. The determination of the liquid absorption capacity showed that, of the synthetic fabrics, the one with the highest absorption, both in distilled water and in brackish water, was the polyester (PES) fabric with an absorption of 816% compared to its initial weight. In the natural fabrics, the highest absorption capacity was shown by the wet-laid without treatment (WL-WT) fabric for both distilled water and brackish water, although it required several cycles of operation to maintain this stable absorption. Exposure to brackish water improved the absorption capacity of all samples. Mechanical and thermal characterization showed that the synthetic fabrics were more resistant than the natural fabrics, although they may compete in terms of applicability. The capillarity study showed that the most hydrophilic fabrics completed the test the fastest. Finally, the composting degradation test showed that those fabrics with polylactic acid (PLA) content degraded faster in the first 14 days and thereafter the degradation of the lignocellulosic content showed a slower degradation until 112 days. The Bam fabric did not degrade during the course of the experiment.

Microplastics in agricultural soils in China: Sources, impacts and solutions

The detection of microplastics (MPs) in agricultural soils has raised alarms on their potential impacts on agricultural production, particularly in China where agriculture has great importance for domestic consumption and export. This review aims to present the abundance, sources and impacts of MPs in the agricultural soils of China. It has the novelty of synthesizing sustainable agronomic practices to reduce MPs pollution of agricultural soils based on the sources identified. According to the extant study, the abundance of MPs in the agricultural soils in China ranged from 4.94 items/kg in the lower reaches of Yangtze River to 40,800 items/kg in Yunnan Province. The MPs were predominantly ≤1 mm and were mainly composed of fragments, films and fibers. Polyethylene and polypropylene MPs were most reported. Plastic mulching films were the most significant source of MPs in agricultural soils, followed by abandoned greenhouses and the use of organic fertilizers containing fugitive MPs or whose sources were often MPs-polluted. MPs were found to alter soil physicochemical properties for instance, water flow, water-stable aggregates, soil aggregation, soil pH, bulk density and nutrient contents. MPs also affect soil biota through changing the richness and diversity of soil microbial community while retarding growth and disrupting physiological functions of soil macrofauna. The effects of MPs on crops vary and range from alteration of biomass, metabolism and nutrient demands to impacted photosynthesis. Sustainable solutions include the use of grass clippings - straw mix as organic mulches, the use of compost as soil amendment in conjunction with grass-straw mix and incorporation of weed-suppressing biomass into compost, the use of jute and biodegradable plastics for greenhouses, proper decommissioning of abandoned greenhouses as well as setting standards for allowable MPs contents in organic fertilizers and irrigation water.

Photocatalytic degradation of low-density polythene using protein-coated titania nanoparticles and Lactobacillus plantarum

The biodegradation of low-density Polyethylene (LDPE) is usually time-consuming, In the presence of Titania-nanoparticles, LDPE is photocatalytically degraded in smaller fragments afterward the bacteria can effectively degrade polyethylene. In the current study, potent polyethylene degrading bacteria were screened from the soil of the local dumpsite and identified using 16s rRNA sequencing. The protein-coated titania nanoparticle (TNPs) was synthesized using Sol-gel Method and characterized by XRD, and SAED-HRTEM. The photocatalytic biodegradation of LDPE (30 microns) in presence of 1M NaOH was studied by exposing it to UV irradiation, visible light, and high temperature (50°C) for 21 days separately and photocatalytic biodegradation was assessed by monitoring % weight loss at every 7 days' time interval, tensile strength, and FTIR. After 21 days of photocatalytic biodegradation, LDPE film containing both TNPs and Lactobacillus plantarum along with 1M NaOH in presence of visible light was unveiled oxidation and enumerated via the occurrence of strong absorptions band of the carbonyl group (C=O) and also the breaking and weakening of existing absorptions bonds along with the new carbonyl functional group formation. The decline in tensile strength was measured at 21% after 21 days. Thus, experimental results on LDPE after exposure to visible irradiation along with Lactobacillus plantarum and 5% protein-coated TNP showed improvement in degradation rate and elongation 59 % and 51% within 21 days, respectively in comparison to another study (49 % Weight loss and 12% elongation after 45 days). An excellent application of this research is significantly reduced plastic waste via a maintained procedure.

High density polyethylene (HDPE) biodegradation by the fungus Cladosporium halotolerans

Polyethylene (PE) is high molecular weight synthetic polymer, very hydrofobic and hardly biodegradable. To increase polyethylene bio-degradability it is very important to find microorganisms that improve the PE hydrophilic level and/or reduce the length of its polymeric chain by oxidation. In this study, we isolated Cladosporium halotolerans, a fungal species, from the gastric system of Galleria mellonella larvae. Here, we show that C. halotolerans grows in the presence of PE polymer, it is able to interact with plastic material through its hyphae and secretes enzymes involved in PE degradation.

Preparation, biocontrol activity and growth promotion of biofertilizer containing Streptomyces aureoverticillatus HN6

Nowadays, due to the excessive dependence on chemical fertilizers and pesticides in agricultural production, many problems, such as soil hardening and soil-borne diseases, have become increasingly prominent, which seriously restrict the sustainable development of agriculture. The application of microbial fertilizer prepared by biocontrol microorganisms can not only improve soil structure and increase fertility but also have the function of controlling diseases. Streptomyces aureoverticillatus HN6 has obvious disease prevention and growth promotive effect, which can improve the rhizosphere fertility of plants and even regulate the rhizosphere microbial community of plants. Based on the comparison of frame composting and natural composting, we used the response surface method to optimize the preparation conditions of Streptomyces HN6 bacterial fertilizer. The results showed that natural composting not only produced higher composting temperatures and maintained long high temperature periods in accordance with local conditions, but was also more suitable for composting in the field according to local conditions. Therefore, the substrate's conductivity changed more, the ash accumulation increased, and the substrate decomposed more thoroughly. Thus, this composting method is highly recommended. Additionally, Streptomyces HN6 microbial fertilizer EC20 can reduce cowpea fusarium wilt and promote cowpea growth. The number of plant leaves, plant height and fresh weight, increased significantly in the microbial fertilizer EC20. Moreover, Streptomyces HN6 fertilizer EC20 could significantly induce soil invertase, urease and catalase activities. Our study highlights the potential use of Streptomyces HN6 as a biofertilizer to improve plant productivity and biological control of plant pathogenic fungi.

Performance evaluation of conventional and hybrid woven fabrics for the development of sustainable personal protective clothing

This study examines the performance level of hybrid woven protective clothing (HWPC), manufactured from Kevlar® (K) and Ramie (R) yarns. The weave structures (plain, twill 1/3) and variables fiber ratios were used to produce HWPC. The performance level of HWPC was measured according to EN 388:2016. We came to the conclusion that blade cut resistance of plain and twill structure sustained protection level up to increase of KR 80:20 and KR 70:30, respectively; puncture resistance of K100% and HWPC remained in the same level of protection for plain and twill weaves; Abrasion resistance of K100% and HWPC of plain and twill weaves samples presented abrasive performance of same protection level, but the average number of cycles sustained for twill weave samples was slightly higher than plain weave. However, comparing the plain and twill weaves sample for tear resistance, twill weave samples have higher tear resistance than plain weave. A gray relational analysis and Taguchi method was performed to optimize the performance of two structures with variable fiber ratios. It was established that the article produced with K&R yarns with KR 80:20 ratio and twill weave presented the best performance against all test runs. The main objective of this study is to reduce plastic pollution by reducing the amount of synthetic fiber proportion in personal protective clothing and thereby reducing the dependence on nonrenewable sources for synthetic fiber. The 41 g/m2 reduction of Kevlar® fiber has been made in a conventional PC with ramie fiber, without compromising the protection level. This will enhance the sustainability of HWPC.

Comparative life cycle assessment of coffee jar lids made from biocomposites containing poly(lactic acid) and banana fiber

Composites containing bio-based materials, like banana fiber and poly(lactic acid) (PLA), are potential food-packaging materials. We carried out an environmental life cycle assessment (LCA) of coffee jar lids made from high density polyethylene (HDPE), PLA, and banana fiber to assess their environmental performance. We considered differences in the type of blend (content of PLA and banana fiber in the composite), origin of the banana fiber feedstock (considered as either biowaste or as a co-product from banana production) and banana fiber pretreatment conditions (either no pretreatment or pretreatment using chemicals). Irrespective of the scenario, a lid made from 40% banana fiber and equal amounts of HDPE and PLA performed significantly better in all 18 impact categories when compared to a lid made from 100% PLA. By contrast, the same lid performed significantly better in 3 impact categories only (climate change, photochemical oxidant formation and fossil depletion) when compared to a lid made from 100% HDPE. Thus, environmental performance of the biocomposite strongly depends on which polymer base is replaced by the banana fiber in the composite. Replacing PLA with banana fiber is generally expected to bring environmental benefits.

Microbial degradation and other environmental aspects of microplastics/plastics

Microplastic (MP) pollution is a significant environmental concern due to the persistence of MPs and their potential adverse effects on biota. Most scientific studies have examined the distribution, ingestion, fate, behavior, amount, and effect of MPs. However, few studies have described the development of methods for the removal and remediation of MPs. Therefore, in this review, we summarize the recent literature regarding the microbial-mediated degradation of MPs and discuss the associated degradation characteristics and mechanisms. Different types and combinations of microorganisms, such as bacteria, fungi, bacterial consortia, and biofilms, that can degrade different MPs are categorized. This article summarizes approximately 50 recent papers. Twelve and 6 papers reported that bacteria and fungi, respectively, can degrade MPs. Nine articles indicated that bacterial consortia have the ability to degrade MPs, and 6 articles found that biofilms can also utilize MPs. Furthermore, to evaluate their associated degradation effects, the corresponding structural changes (i.e., macro size, surface morphology, and functional groups) in MPs after microbial degradation are examined. In addition, MP biodegradation is affected by microbial characteristics and environmental factors; therefore, the environmental factors (i.e., temperature, pH and strain activity) influencing MP degradation and the associated degradation effects (i.e., weight loss, degradation rate, and molecular weight change) are generalized. Furthermore, the mechanisms associated with the microbial-mediated degradation of MPs are briefly discussed. Finally, prospects for the degradation of MPs using microbes and future research directions are envisioned. This review provides the first systematic summary of the microbial-mediated degradation of MPs and provides a reference for future studies investigating effective means of MP pollution control.

Biodegradation of low-density polyethylene (LDPE) by mixed culture of Lysinibacillus xylanilyticus and Aspergillus niger in soil

In this study, two strains of Aspergillus sp. and Lysinibacillus sp. with remarkable abilities to degrade low-density polyethylene (LDPE) were isolated from landfill soils in Tehran using enrichment culture and screening procedures. The biodegradation process was performed for 126 days in soil using UV- and non-UV-irradiated pure LDPE films without pro-oxidant additives in the presence and absence of mixed cultures of selected microorganisms. The process was monitored by measuring the microbial population, the biomass carbon, pH and respiration in the soil, and the mechanical properties of the films. The carbon dioxide measurements in the soil showed that the biodegradation in the un-inoculated treatments were slow and were about 7.6% and 8.6% of the mineralisation measured for the non-UV-irradiated and UV-irradiated LDPE, respectively, after 126 days. In contrast, in the presence of the selected microorganisms, biodegradation was much more efficient and the percentages of biodegradation were 29.5% and 15.8% for the UV-irradiated and non-UV-irradiated films, respectively. The percentage decrease in the carbonyl index was higher for the UV-irradiated LDPE when the biodegradation was performed in soil inoculated with the selected microorganisms. The percentage elongation of the films decreased during the biodegradation process. The Fourier transform infra-red (FT-IR), x-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to determine structural, morphological and surface changes on polyethylene. These analyses showed that the selected microorganisms could modify and colonise both types of polyethylene. This study also confirmed the ability of these isolates to utilise virgin polyethylene without pro-oxidant additives and oxidation pretreatment, as the carbon source.