Fate of four phthalate plasticizers under various wastewater treatment processes

Air-Sea Exchange and Atmospheric Deposition of Phthalate Esters in the South China Sea

Phthalate esters (PAEs) have been investigated in paired air and seawater samples collected onboard the research vessel SONNE in the South China Sea in the summer of 2019. The concentrations of ∑₇PAEs ranged from 2.84 to 24.3 ng/m³ with a mean of 9.67 ± 5.86 ng/m³ in air and from 0.96 to 8.35 ng/L with a mean of 3.05 ng/L in seawater. Net air-to-seawater deposition dominated air-sea exchange fluxes of DiBP, DnBP, DMP, and DEP, while strong water-to-air volatilization was estimated for bis(2-ethylhexyl) phthalate (DEHP). The estimated net atmospheric depositions were 3740 t/y for the sum of DMP, DEP, DiBP, and DnBP, but DEHP volatilized from seawater to air with an average of 900 t/y. The seasonally changing monsoon circulation, currents, and cyclones occurring in the Pacific can significantly influence the concentration of PAEs, and alter the direction and magnitude of air-sea exchange and particle deposition fluxes. Consequently, the dynamic air-sea exchange process may drive the transport of PAEs from marginal seas and estuaries toward remote marine environments, which can play an important role in the environmental transport and cycling of PAEs in the global ocean.

A hypothetical model of multi-layered cost-effective wastewater treatment plant integrating microbial fuel cell and nanofiltration technology: A comprehensive review on wastewater treatment and sustainable remediation

Wastewater management has emerged as an uprising concern that demands immediate attention from environmentalists worldwide. Indiscriminate and irrational release of industrial and poultry wastes, sewage, pharmaceuticals, mining, pesticides, fertilizers, dyes and radioactive wastes, contribute immensely to water pollution. This has led to the aggravation of critical health concerns as evident from the uprising trends of antimicrobial resistance, and the presence of xenobiotics and pollutant traces in humans and animals due to the process of biomagnification. Therefore, the development of reliable, affordable and sustainable technologies for the supply of fresh water is the need of the hour. Conventional wastewater treatment often involves physical, chemical, and biological processes to remove solids from the effluent, including colloids, organic matter, nutrients, and soluble pollutants (metals, organics). Synthetic biology has been explored in recent years, incorporating both biological and engineering concepts to refine existing wastewater treatment technologies. In addition to outlining the benefits and drawbacks of the current technologies, this review addresses novel wastewater treatment techniques, especially those using dedicated rational design and engineering of organisms and their constituent parts. Furthermore, the review hypothesizes designing a multi-bedded wastewater treatment plant that is highly cost-efficient, sustainable and requires easy installation and handling. The novel setup envisages removing all the major wastewater pollutants, providing water fit for household, irrigation and storage purposes.

Enhanced photoelectrocatalytic performance for degradation of dimethyl phthalate over well-designed 3D hierarchical TiO2/Ti photoelectrode coupled dual heterojunctions

A novel A/R-TiO₂ NSs/NRs photoelectrode was constructed through electrodeposition of anatase TiO₂ nanosheets (A-TiO₂ NSs) with highly exposed {001} facet onto the 1D upright rutile TiO₂ nanorods (R-TiO₂ NRs). At first, A/R-TiO₂ NSs/NRs exhibited enhanced adsorption of dimethyl phthalate (DMP) due to the specific recognition between Lewis acid sites of {001} facet and Lewis basic DMP. NH₃-TPD and Py-IR revealed that the Lewis acidity on the {001} facet of A-TiO₂ NSs was much stronger than that of R-TiO₂ NRs, demonstrating superior adsorption capacity to DMP. DFT theoretical calculations coupled with in-situ ATR-FTIR spectra were performed to investigate the binding adsorption behavior of DMP on A/R-TiO₂ NSs/NRs. Secondly, the rapid separation of excited charges and strong oxidation of h⁺ were achieved by the synergistic effect of dual heterojunctions (A/R "phase heterojunction" and {111}/{110} "facet heterojunction"). The A/R-TiO₂ NSs/NRs exhibited 100% degradation efficiency for the target pollutant DMP within 3 h, whose rate constant (k) was 18.02 × 10^-3 min^-1, 2.16 times that of pure R-TiO₂ NRs. In real wastewater application, A/R-TiO₂ NSs/NRs achieved 93.8% elimination of DMP during 4 h and preserved excellent stability after 5 cycles, promising a wide-range of applications in water environment remediation.

Evaluation of occurrence, fate and removal of priority phthalate esters (PAEs) in wastewater and sewage sludge by advanced biological treatment, waste stabilization pond and constructed wetland

Phthalate Esters (PAEs), detected in high concentrations generally in treated wastewater discharged from wastewater treatment plants (WWTPs), are important pollutants that restrict the reuse of wastewater. Investigating the fate of these endocrine-disrupting chemicals in WWTPs is crucial in order to protect both receiving environments and ecosystems. For this purpose, di(2-ethylhexyl) phthalate (DEHP), di-n-octyl phthalate (DNOP) and benzyl butyl phthalate (BBP) in the group of PAEs were monitored in simultaneously both in wastewater and sludge lines of selected two nature-based WWTPs and one advanced biological WWTP. Although it was frequently stated that phthalates were significantly removed in WWTPs in many studies found in literature, negative removal efficiencies of selected phthalates in investigated WWTPs during the sampling period were observed generally in this study. One of the reasons for this concentration increase could be releasing of phthalates from microplastics in wastewater during the treatment process or the desorption of PAEs from treatment sludge. DNOP was the compound with the highest concentration increase at almost each treatment unit of the three WWTPs. On the other hand, total PAEs load was 1997 g d^-1 in advanced biological WWTP and adsorption onto sludge of PAEs were determined as 90%. The side-stream total load returned from the decanter supernatant was 0.02% of the total PAEs load coming to advanced biological WWTP from the sewer system. As a result of detailed statistical analysis, the correlation between raw wastewater and primary clarifier (PC) effluent was determined as an increasing linear relation for DEHP and DNOP. On the other hand, moderate and strong correlations were observed both between septic tank and constructed wetland (CW) processes with raw wastewater. In the waste stabilization pond (WSP), while a significant correlation was not found between the sludge line data, homogeneous variance, strong and moderate correlations were obtained in the wastewater line data. However, while mean differences for all investigated PAEs were not significant (p > 0.05) in the wastewater line, mean differences of DEHP (p < 0.05) were significant in the sludge line according to ANOVA analysis.

Occurrence, effects, and biodegradation of plastic additives in sludge anaerobic digestion: A review

The retention of microplastics, a complex blend of polymers and plastic additives (PAs), in municipal sludge has been reported. The inevitable release of PAs from microplastics might affect the subsequent biological disposal of sludge, and their final fate are of great public concern. Therefore, this review describes the current knowledge in the occurrence of PAs in sludge and significant advances in their effects on sludge anaerobic digestion (AD) and their biodegradation performance. Specifically, the compositions and contents of plasticizers, stabilizers, and flame retardants in sludge worldwide are systematically summarized. The discrepant impacts of PAs on hydrolysis, acidification, and methanogenesis processes are analyzed and compared, with corresponding trends deduced. Furthermore, the biodegradation performances of PAs during sludge AD are also discussed. For most of the PAs detected in sludge, available data for their fate and effects on AD is yet limited. Moreover, the potential role of AD microbes in the release of PAs from microplastics was still unknown. Especially, the potential effects of PAs released from biodegradable microplastics on sludge AD and their fate should be of concern. The obtained knowledge would update our understanding of the risk assessment and control of PAs in sludge AD. Recommendations for future investigation are made.

The Py - GC-TOF-MS analysis and characterization of microplastics (MPs) in a wastewater treatment plant in Gauteng Province, South Africa

Wastewater treatment plants (WWTPs) in South Africa, like is the case for most WWTPs around the globe albeit capable of removing substantial quantities of microplastics (MPs) and in fact, the treatments become ineffective for those plastic particles less than 100 µm. As a consequence, the receiving water bodies in which the final effluent is discharged becomes highly polluted. The present research is devoted to the analysis of the pervasive MPs in wastewaters of the treatment plant located in the Gauteng Province, South Africa using Pyrolysis - GC-TOF-MS. Based on the results, there were 23 pyrolyzate products with contributions from PVC, PA, PET and PE with abundances of 47.8%, 13.1%, 17.4% and 4.3% respectively. The remaining 17.4% could be attributed as additives in MPs. The SEM images illustrated that the MPs appeared to be inter - wined, fibrous of different thicknesses and lengths. The highly weathered MPs exhibited the rough surface which was noticeably damaged with peeled off layers presumably because of photo-oxidation during the aging process. The vibrational modes of FTIR revealed the presence of the various functional groups in the corresponding polymers of MPs. The thermal studies confirmed the presence of calcium, aluminum and silicon as residues of catalysts or flame retardants or UV stabilizers in MPs or as adsorbates resulting from the surface adsorption from the surroundings. The Py-GC-TOF-MS confirmed the identity of the various fragments related to the MPs monomers.

Bacterial community progression during food waste composting containing high dioctyl terephthalate (DOTP) concentration

The overall dioctyl terephthalate (DOTP) degradation efficiency during food waste composting was 98%. The thermophilic phases contributed to 76% of the overall degradation efficiency, followed by the maturation phase (22%), then the mesophilic phase (0.7%). The thermophilic phase had the highest specific degradation rate of 0.149 d^-1. The progression of the bacterial community during the composting process was investigated to understand DOTP biodegradation. The results showed that the bacterial richness and the alpha diversity of the DOTP composting were similar to a typical composting process, indicating that the high concentration of DOTP did not hinder the thriving and evolution of the bacterial community. Additionally, Firmicutes was the most dominant at the phylum level, followed by Proteobacteria and Bacteroidetes. Bacilli was the most dominant class (70%) in the mesophilic phase, with the abundance decreasing thereafter in the thermophilic and maturation phase. Moreover, Lactobacillus sp. was the dominant species at the beginning of the experiment, which was probably responsible for DOTP biodegradation. The high removal efficiency observed in the maturation phase indicates that degradation occurs in all the composting phases, and that compost can be used to enhance natural attenuation. These findings provide a better understanding of the bacterial communities during biodegradation of DOTP and plasticizers via food waste composting and should facilitate the development of appropriate green bioremediation technologies.

Assessment of migration regularity of phthalates from food packaging materials

Phthalate acid esters (PAEs) are one of the essential plastic additives which may lead to plenty of harmful effects, including reproductive toxicity, teratogenicity, and carcinogenicity. Increasing attention has been paid to the migration of plasticizer. In this article, the disposable plastic lunch boxes were taken as the research object. The result showed that dibutyl phthalate (DBP) and diisobutyl phthalate (DIBP) have been mainly found, whose content was 1.5 mg/kg and 2.4 mg/kg, respectively. The LOD was 2 ng/g, and LOQ was 6.7 ng/g. We further investigated the migration of PAEs into the simulated liquid at different temperature conditions. Then, the linear fitting performing by first-order kinetic migration model revealed that the lower the polarity of the simulated liquid, the larger the rate constant K 1 and initial release rate V 0. The higher the temperature, the bigger the K 1 and V 0.

Detecting phthalate esters in sludge particulates from wastewater treatment plants

This study proposed a method for analysis of 10 phthalate esters compounds from wastewater treatment plant sludges. The analytical efficiency of GC-MS for of target compounds was verified by a standard mixture of phthalate esters. The response factors related to the respective internal standards from a five-point calibration curve quantified the phthalate esters in individual compounds. Based on the literature compiled by environmental agencies, new generation phthalate compounds have been developed, such as di-iso-nonyl phthalate (DiNP), di-iso-decyl phthalate (DiDP), as alternative to conventional phthalates. The analytical results showed that the total PAEs concentration was in the range from 7.4 to 138.6 mg kg^-1 dw in these seven analyzed sludge samples. More, di-iso-nonyl phthalate (DiNP), di-iso-decyl phthalate (DiDP) and bis(2-ethylhexyl) phthalate (DEHP) contributed to over 99% of PAEs in the sludge. The correlation between total PAEs concentration in household and sewage flow treated at seven WWTPs and concentrations of DEHP, DiNP and DiDP was significant.

Biosolids and sludge management

The advancements in the field of sludge and biosolids have been made over the past year. This review outlines the major contributions of researchers that have been published in peer-reviewed journals and conference proceedings throughout 2018. The review is organized in sections including regulatory developments and market analysis; analysis and quantification of characteristics including microconstituents and metals; treatment advances for the conversion of sludge to biosolids including pretreatment and sludge minimization, conditioning and dewatering, digestion, composting, and innovative technologies; product development and reuse including adsorbents and thermal products, agricultural and other uses, and innovative uses; odor and air emissions; and energy factors. PRACTITIONER POINTS: Summary of advances in the field of residuals and biosolids research in 2018. This review outlines the major contributions of researchers that have been published in peer-reviewed journals and conference proceedings. Topics covered range from regulation to innovation.