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Agricultural wastes are inexpensive materials for soil remediation. However, the direct water extracts from these wastes showed low efficiency for Pb removal, thus limiting their application. In this study, citrus pericarp (CP) and pineapple peel (PP), as the common agricultural wastes, were inoculated with lactic acid bacteria to produce fermentation liquors (FCP and FPP) for improving Pb removal efficiency. Results showed that the Pb removal rates by FCP and FPP reached 37.3 and 43.6%, and increased by almost 50.0% than those by CP and PP. The ecological risk of Pb reduced by 83.0-88.2% after five times continuous washing with FCP and FPP, and the Pb concentrations conformed to soil remediation standard of China. Moreover, soil organic carbon 1.5 times increased in the washed soils, while total potassium improved by 40.7-68.0%. The mechanisms of Pb removal by these wastes involved in adsorption-desorption of Pb

Background Oil spills and leaks of organic pollutants have caused threats to the aquatic environment. Biomass sponges are potential absorbent materials to achieve oil–water separation due to their being low-cost and environmentally friendly. However, the ability to separate oil and water still mainly depends on preparing low-density sponges with high absorbability and motion controllability through mild and low-cost strategies. Methods In this study, an ultralow-density biomass sponge was prepared via a facile hydrothermal method through a Fenton-like reaction using pears as raw material. Notably, a Fenton-like reaction was introduced for the fabrication of a hydrothermal process for performance optimization. In addition, a small amount of polydimethylsiloxane and magnetic nanoparticles were used to modify the surface of the pear sponge through a one-step method. Findings The prepared biomass sponge exhibited a novel recyclability, hydrophobicity with water contact angle of 137°, stable magnetic properties and ultra-low density(0.03 g/cm3). The pear sponge also demonstrated excellent sorption capacity, achieving up to 10-20 times of its own weight for a wide range of organic solvents and oils. The prepared magnetic-driven sponges can be applied in emergencies for leakages of organic solvents, as well as leakages from tankers and offshore drilling platforms.

The purpose of this study is twofold: First, to develop new sustainable design methods (aligned with ethnic elements and traditional culture) combined with three-dimensional digital clothing technology throughout the design process, which can be presented as guideline materials for various fashion designs to be developed in contemporary sensibilities. Second, it is the intention to produce creative fashion designs by incorporating the characteristics and methods of Miao’s Huangping batik dyeing technique and to present various possibilities in the fashion design field. The overall design characteristics sought by Miao minority are in line with the complex terrain and the ecological and climatic conditions. Miaoist batik dyeing (registered as part of Chinese national intangible cultural heritage) features unique production methods and patterns. The study results are as follows. First, this attempt has enabled understanding of the national costume culture as Chinese Miao’s traditional cultural heritage to be promoted, while the direction of contemporary design development using traditional elements has been presented. Second, the study demonstrated new and innovative expressions and styles relying on three-dimensional digital contouring technology and identified the possibility of developing various designs. Third, it was confirmed that the dyed batik pattern design created by the three-dimensional digital contouring technology could be recombined or expanded as digital printing to express the traditional ethnic designs in a practical manner utilizing digital printing techniques based on traditional characteristics.

Utilization of allelochemicals to inhibit overgrowth of toxic cyanobacteria is considered to be an environmentally friendly approach. However, the regulatory role of the signaling molecule nitric oxide (NO) on cyanobacteria under allelopathic stress remains unanswered. Here we demonstrate that the effect of NO on the cyanobacterium Microcystis aeruginosa depends on allelopathic stress of pyrogallic acid (PA). The experimental results revealed that general stimulation of M. aeruginosa by PA occurred within the concentration range 0.4-0.8 mg/L. In parallel with increasing concentration of PA (1.6-16.0 mg/L), the growth of M. aeruginosa was observed to decrease. The effect of NO on M. aeruginosa was evaluated by addition of the NO scavenger hemoglobin. In the stimulation stage, intracellular NO was seen to decreased to modulate the level of reactive oxygen species (ROS) and to maintain redox homeostasis of the cells. In the inhibition stage, the physiological characteristics of M. aeruginosa were changed significantly. Additionally, the accumulation of S-nitrosothiol by M. aeruginosa indicated that the high concentrations of PA induced nitric oxidative stress in M. aeruginosa. This study provides a new thought to understand the role of NO in controlling harmful algal blooms through the allelopathic effect of aquatic macrophytes.

The application of modified clay is an effective and common method to control harmful algal blooms (HABs), but the impact on benthic organisms caused by the settlement of clay–algae flocs (CAFs) should also be considered. In this study, a simulation experiment was carried out to investigate the responses of antioxidant enzyme activities and the accumulation dynamics of microcystins (MCs) in Corbicula fluminea to CAFs after migrating HABs to the sediment surface via chitosan-modified clay. We collected sediments, C. fluminea, algal cells, and lake water from Sancha Lake in Sichuan in June 2020. We simulated four treatments in the experiment—a control treatment, a modified clay treatment, an algal cells treatment to simulate the natural deposition of algae, and a modified clay with algal cells treatment. Then, each treatment was quickly stirred for 3 min (100 r min−1), and then slowly stirred for 20 min (30 r min−1). Water and sediments samples were taken at 3, 7, and 15 days to determine the chlorophyll-a and MCs, and C. fluminea samples were collected to analyze the MC content and antioxidant enzyme activity and malondialdehyde content. One-way ANOVA was used to identify the differences between each treatment. Results showed that the enzyme activities of catalase, glutathione reductase, glutathione peroxidase and superoxide, and superoxide dismutase in the controlling HABs treatment were significantly lower at the end of the experiment compared with the control and the other two treatments—namely, clay only, and algal cells only—while the malondialdehyde content was significantly higher than in the other three treatments, indicating that deposition of CAFs resulted in oxidative damage in C. fluminea. Moreover, a significant increase in MCs in sediments and C. fluminea was also found after deposition of CAFs at 7 and 15 days, which represents a disadvantage of applying modified clay to control HABs. This study shows that the application of chitosan-modified clay to control HABs can result in the reduction of antioxidant enzyme activities in C. fluminea, ultimately leading to their death with a mortality rate significantly higher compared with the control. Moreover, an accumulation trend of MCs in C. fluminea was also found in the HABs control treatment.

Due to the potential ecological risks of organic pollution in sediments, aquatic ecosystems are currently facing substantial environmental threats. Assessing and controlling sediment pollution has become a huge challenge. Therefore, this study proposes a novel strategy for predicting organic pollution indicators for sediment, as well as an effective resource-utilization method. Contaminated sediments were converted into catalysts for sulfate radical advanced oxidation technologies by a one-step calcination method. The results revealed that the catalyst excelled in activating peroxymonosulfate to degrade tetracycline via a non-radical pathway. Most importantly, a predictive model of organic pollution indicators was established by machine learning. This study provides a novel approach for resource utilization and a strategy for assessing organic pollution in sediments.

Cd is a heavy metal that contaminates soils. These kinds of heavy metals pose a serious threat to food security, ecosystems, and human health. To improve the phytoremediation efficiency of moderately Cd-contaminated cropland soils and achieve simultaneous production and remediation, intercropping ryegrass (Lolium perenne L.) with hollyhock (Althaea rosea) was investigated using pot experiments, and Bacillus thuringiensis (B. thuringiensis) inoculation was used as a booster to strengthen the absorption and accumulation of Cd in plants. The results showed that intercropping (Int treatment) decreased the Cd concentration in plants compared to hollyhock and ryegrass monocropping. However, the Cd accumulation in ryegrass and hollyhock was promoted by B. thuringiensis addition to intercropping (Int-B treatment), as the biomass of ryegrass and hollyhock was 2.33 and 1.13 times that of the Int treatment, respectively. Compared with the Int treatment, the total Cd concentration in soils of the Int-B treatment decreased by 8.1%, while diethylenetriaminepentaacetic acid solution extracted Cd (DTPA-Cd) increased by 18.2%, indicating that B. thuringiensis increases the available Cd concentration in soils to promote Cd adsorption by hollyhock enrichment plants. High-throughput sequencing results further revealed that the dominant microflora in the soils of the Int and Int-B treatments were consistent with the control, although their abundance and diversity decreased slightly. Overall, intercropping with B. thuringiensis addition effectively increased the hollyhock remediation efficiency in moderately Cd-contaminated soils, and the concentration of Cd in forage crops of ryegrass was lower than the limit value of "Hygienic standards for feeds' (GB 13078-2017) in China.

Microplastics (MPs) have attracted widespread attention as an organic class of pollutants as well as pollutant carriers in recipient aquatic ecosystems. In this study, tetracycline (TC) adsorption by polystyrene (PS), with multiple aging-based temporal changes in the adsorption mechanism, was observed. The results revealed that the pseudo-second-order model accurately predicted the TC adsorption kinetics for different types of PS. In addition, the isothermal adsorption processes fit the Freundlich model; however, their interactions were drastically weakened at lower temperatures or increasing salinities. Corresponding to the electrostatic interactions, adsorption TC was largely pH-dependent, with the maximum adsorbed TC content on the PS surface at a pH of 5 in an aqueous environment. More importantly, mechanistic studies have revealed that, compared to virgin PS, TC complexes with aged PS are principally controlled by hydrogen bonding and ionic interactions, followed by π-π, polar-polar, and van der Waals interactions. These findings will aid in understanding the insights of TC and aged PS interactions and the underlying interactive molecular forces, which will be advantageous for comprehending the real case scenario of inter-pollutant interactions and related environmental pollution.

The direct discharge of urine into water bodies leads to environmental pollution, and an increase in the water treatment cost, whereas recycling of the nutrients in urine is of significant economic value. A single-compartment reactor was investigated for the recycling of phosphate and simultaneous removal of nitrogen from urine wastewater by electrochemical magnesium induction, and electrochemical oxidation for the removal of residual nitrogen from the supernatant. The results demonstrated that phosphate recovery capacity was greater than 11 mg P cm−2 h−1 at a current density of 15 m A cm−2 and anodizing time of 20 min; the removal rates of ammonium and total nitrogen in the synchronous electrochemical oxidation were 80% and 75%, respectively, at a current density of 45 m A cm−2 and anodizing time of 60 min. The anodizing time and initial pH were determined to be critical control factors in the electrochemical struvite induction and nitrogen electrochemical oxidation. The on-site electrochemical nitrogen oxidation could rapidly utilize the alkaline supernatant following phosphate recovery. Thus, the integration of the single-compartment reactor, electrochemical magnesium dosage, and simultaneous nitrogen electrochemical oxidation demonstrates potential for application to decentralized reactors to treat source-separated urine.

Silicates have been used as soil heavy metal passivators, but low remediation efficiency limited their development. In order to solve this problem, in this paper, an economical and environmentally friendly amorphous iron silicate was prepared by a simple co-precipitation method. It could be proved from the passivation experiments that the remediation efficiency of amorphous iron silicate (AIS) on Cd-contaminated soil was better than that of natural silicates (montmorillonite and diatomite), which reflected the superiority of amorphous materials. Plant experiments showed that AIS could effectively inhibit the absorption and accumulation of Cd

Biochars produced from crab shell (CSB), oak sawdust (OB), Jerusalem artichoke tuber (JAB) and sorghum grain (SB) displayed distinguishable adsorption-related characteristics, such as specific surface area (SSA), ash content and acidic oxygen-containing functional groups (AFGs), which linked to the biochar adsorption mechanisms of most pollutants. Herein, PO43–, Cd2+, and nitrobenzene (NB) were employed for adsorption by these biochars to elucidate the dominant factors for the adsorption. Adsorption performance of the three pollutants onto these four biochars varied considerably, as exemplified by the excellent adsorption of PO43– and Cd2+ onto CSB (225.3 and 116.0 mg/g, respectively) as compared with onto the other three biochars (4.2–37.1 mg/g for PO43– and 9.7–41.0 mg/g for Cd2+). OB displayed the best adsorption of NB (72.0 mg/g), followed by SB (39.5 mg/g), JAB (31.1 mg/g), and CSB (23.6 mg/g). The kinetics and isotherm adsorption assessments couple with material characterization suggested that the sorption of selected pollutants on biochars was attributed to the multiple mechanisms involved, including coprecipitation, chemical bonds, cation exchange, physical absorption, and complexation. Further path analysis suggested that AFGs and ash content in biochars were more important than SSA with regards to pollutant removal, especially, with ash playing a crucial role in the removal of Cd2+ and PO43–, and AFGs being mainly responsible for NB adsorption. These findings might offer guidance on the preparation or modification of biochar with a targeted function for pollutant removal through an understanding the dominant factors.

Microplastics are the critical carriers of heavy metals in the environment. Thus, investigating the adsorption mechanisms between the microplastics and heavy metals is helpful to understand the migration and transformation pattern of the heavy metals in the environment. The adsorption of microplastics towards heavy metals can be largely affected by natural aging (e.g., UV-aging), environmental pH, and salinity. In this study, the adsorption of polystyrene (PS) towards Cu

The iron (Fe) cycle in the rice-soil system affects arsenic (As) uptake by rice. The effect of Fe on As uptake can be influenced by the addition of biochar, but has not been thoroughly investigated. In this study, the effects of maize straw-derived biochar (MB) on Fe and As translocation were determined by analysing the Fe and As concentrations in pore water, dithionite-citrate-bicarbonate (DCB) extracts, and rice plants. As-contaminated soils were supplemented with 0 or 1% biochar and 0 or 90 mg kg−1 P, and rice plants were grown for 70 d. Results indicated that biochar addition increased the concentrations of Fe and As in pore water, while P did not affect them. Additionally, biochar promoted the accumulation of Fe and As in roots. However, the rice biomass increased by 28% upon biochar addition, indicating that the rice plants became more tolerant to As toxicity with biochar. Specifically, biochar increased the root triphenyl tetrazolium chloride (TTC) reductive intensity, reduced the root H2O2 concentration, and promoted iron plaque (IP) formation. Moreover, the positive correlation between IP/DCB-extractable As and crystalline Fe on the rice root surface indicated that crystalline Fe appeared to be the determinant species of IP and played a central role in As segregation. In addition, biochar increased both crystalline Fe formation on the root surface and the Fe content in the cell wall, which enhanced As sequestration. Overall, rice could effectively tolerate As stress under biochar treatment since As could be retained on the root surface and root cell wall with MB.

Large amounts of microplastics can accumulate in wastewater treatment plants (WWTPs), and sludge disposal is suspected to be a major source of microplastics pollution in the environment. It is therefore important to investigate the distribution of microplastics in the sludge of each processing unit of WWTPs. However, little information is available on this topic in China. Accordingly, in this study, the abundance and characteristics of microplastics in the sludge of two WWTPs in Chengdu were investigated. The abundance of microplastics in the sludge samples ranged from 44.4 n·kg−1 to 750.0 n·kg−1. Microplastics were mainly divided into particles (32.16%), debris (28.14%) and fibers (17.08%) according to their shape, and the colors of the microplastics were mainly green (35.19%) and translucent (18.06%). The particle sizes were mainly larger than 1 mm in dimension. Polyethylene, polypropylene and polystyrene were the prevalent types of microplastics analyzed. Our results provide basic information for better understanding the characteristics of microplastics in sludge and for improving sludge treatment.

Agricultural activities and agro-inputs, particularly chemical fertilizers, farmyard manure, pesticide, sewage sludge, plastic mulch, irrigation, etc., are the primary source of pollutants in farmlands. Agricultural land degradation has become a major concern as it poses a threat to crop productivity. In recent years, microbial-assisted phytoremediation has gained much attention as a promising in situ remediation technology for cleaning polluted soils. Several beneficial rhizobacteria and endophytes facilitate phytoremediation by stimulating innate plant growth-promoting traits such as the production of siderophores, phytohormones, and chelators in addition to their ability to biodegrade contaminants and enhance their removal. Current studies on microbial mediated phytoremediation are demonstrating significant remediation potential. However, there are several challenges in the field that restrict the remediation process. Here we highlight the specific traits, mechanisms, roles, advantages, and problems associated with microbial-assisted phytoremediation.

Photoelectrocatalytic (PEC) technology has promising applications. It is capable of effectively generating hydrogen and removing organic pollutant in water at the same time. Though TiO2 materials have been proven an excellent candidate for fabricating PEC electrodes for its low toxicity, high oxidation potential and photocatalytic activity, the catalytic performance of TiO2 electrodes is limited by their low electrons transporting efficiency. In this study, using a facile electrochemical method, we produced single crystalline TiO2 nanotubes (s-TNTs) exposing {001} facets with enhanced charge transfer efficiency than that of common TiO2 nanotubes electrodes (m-TNTs). In this system, the electrochromic s-TNTs electrodes exhibit better performance in generating hydrogen and higher degradation rate of atrazine on s-TNTs than that on common TiO2 nanotubes electrodes (m-TNTs) in varying conditions: electrochemical (EC), photocatalytic (PC), and PEC. Using s-TNTs and s-TNTs@Pd nanocomposites as both photoanode and cathode, the photon-to-current conversion efficiency was significantly enhanced, and the promoted hydrogen production rose obviously. The enhanced charge transfer efficiency of s-TNTs might induce a highly enhancement in the whole PEC system, which could be primarily attributed to the single-crystalline structure and exposed {001} facet. This study could provide new possibility of utilizing single crystalline TiO2 nanotubes for efficient dual-purpose PEC system for its high activity, great stability, low cost and no toxicity.

Water composite pollution is still a great challenge in the field of water treatment. Especially for microplastic (MP), as an emerging pollutant, its wide distribution in water and persistent eco-environmental influence have received great concerns in recent years. Nevertheless, the removal characteristics and mechanism of conventional coagulation on MP composite pollution is quite insufficient. In this study, the coagulation removal performance and mechanisms of MP (polyethylene, PE) and norfloxacin (NOR) was investigated by polyaluminium chloride (PAC) and anionic polyacrylamide (APAM). Compared with single system, the removal efficiency of PE was significantly improved (99.0%) under plateau stage in composite system, while the removal efficiency of NOR was slightly decreased to around 42% regardless of the addition of APAM. The scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), zeta potential and One-way analysis of variance (ANOVA) of experimental data were used to explore the coagulation mechanisms. The results demonstrated that the removal of individual PE and NOR was mainly controlled by charge neutralization and sweep flocculation by PAC and APAM, and adsorption by formation of Al-NOR complex, respectively. Importantly, in composite system, the removal of PE was enhanced not only by the stronger charge neutralization but also the adsorption via the formation of PE-NOR-Al complex. Furthermore, the removal efficiency of PE and NOR in neutral and weak alkaline conditions was higher than that in weak acidic or strong alkaline conditions. The presence of metal ions and humic acid had obvious inhibition and promoting effects on the removal efficiency of PE and NOR. This study can provide a new perspective on fundamental understanding in characteristics and mechanisms of MP composite pollutants removed by coagulation.

Controlling the release of phosphorus (P) in sediments is important to prevent eutrophication and harmful algal blooms in water bodies. Here we explored the effect of mobile aerators on the control of P release from sediments in a eutrophic pond. The dissolved oxygen in the water body recovered significantly after six months of aeration, becoming 4.2–5.8 times higher than in the control. The pH and Eh values at the sediment–water interface considerably increased, while the concentration of soluble reactive phosphorus (SRP) in pore water significantly decreased, resulting in the alteration of SRP fluxes from 1.69 mg/m2 d to −53.49 mg/m2 d. Moreover, the inert P in sediments increased by 5.2% of the total P at the end of the study compared with the initial state, and the calcium-bound phosphorus (HCl–P) increased by 96.6%. However, although aeration reduced the concentration of SRP in the water column, the total P concentration was 2.45 times higher than that of the control, and the content of redox-sensitive P (BD-P) in the sediment also increased by 200%. Overall, although mobile aeration can maintain the microenvironment of the sediment interface and increase the inert P content in the sediment to reduce the P flux, it cannot reduce the risk of release of mobile P.

Soil washing with environmentally friendly eluents is a rapid remediation technique for farmland polluted by heavy metals. In this study, polyepoxysuccinic acid (PESA), ethylenediamine tetra (methylene phosphonic acid) sodium (EDTMPS), and phosphonyl carboxylic acid copolymer (POCA) were applied to remedy paddy and arid soils polluted by Pb and Cd. At the same time, ethylenediaminetetraacetic acid (EDTA) was used as a control eluent. PESA showed comparable removal of soil Pb and Cd (over 80.0%) with EDTA, and EDTMPS and POCA removed two heavy metals by 35.2-50.3%. For labile fractions, PESA significantly removed Pb by 93.5-96.7% and Cd by 84.9-90.3% in two soils. EDTMPS and POCA removed Pb by 75.5-85.8% in two soils, while they only removed Cd by 11.7-42.2% in paddy soil, and 76.3-81.7% in arid soil. The risks of total heavy metal concentrations were reduced from the high risk to low risk in paddy soil, and to considerable risk in arid soil, while only dropped to considerable or even had no change by EDTMPS and POCA leaching. The risks of the two soils reduced from high to low or considerable level after PESA washing based on labile fraction change, and to considerable or high level after EDTMPS and POCA leaching, respectively. Therefore, PESA is an ecological benefit eluent for remediating the farmland polluted by heavy metals, and the risk assessment based on labile fraction more easily identifies the dynamic change of heavy metal during the washing process.