ACS ES&T engineering最新文献

The coexistence of microplastics (MPs) and oil contaminants in soil has led to a new pollution scenario around the oil-production region, yet how to cost-effectively remediate soil with combined pollutants has rarely been explored. Herein, we propose a fast pyrolysis technique to perfectly remediate MP_S-oil copresence soil (MPs-oil-soil). The experimental data showed that pyrolysis at 500 °C for 15 min is a key threshold for the complete removal of MPs and petroleum contaminants from soil. Above this threshold, seed germination and the growth of wheat in the soil increased, and the rhizosphere microbial population decreased with increasing abundance of beneficial microbial flora, such as Proteobacteria, Actinobacteria and Bacteroidetes (which promote the circulation of nutrients and help to strengthen plant resistance). Structural equation modeling revealed that temperature had a more significant positive effect on the remediation effect than did time. Two-dimensional correlation spectroscopy combined with synchronous fluorescence spectroscopy showed that the presence of MPs was the main factor affecting the pyrolysis threshold. Three-dimensional excitation–emission matrix and UV–visible absorption spectroscopy revealed large differences in the aromaticity and relative molecular weight of dissolved organic matter before and after the pyrolysis threshold. These findings shed light on the mechanistic understanding of the pyrolytic remediation of microplastics and oil-contaminated soils.

Human urine is considered a major stream of nitrogen mass flow in domestic wastewater, which is widely available and rich in valuable nutrient resources for hydroponic cultivation. In this study, a promising concept of nutrient recovery from real urine was proposed, including urine alkalinization by Ca(OH)₂, full nitrification in a trickling filter, and chemical supplementations. The steady performance of urine nitrification among different urine-collecting batches indicates the robustness of the trickling filter. An optimal hydraulic loading rate of 2.1 m³ m^–2 h^–1 sufficed the dissolved oxygen and urine circulation in the trickling filter, achieving a nitrate production rate of 223 ± 2 mg N L^–1 d^–1 with an efficiency of 90 ± 2% at pH 6 and 21 °C. The electrical energy consumption was only 1.15 kWh kg^–1 NO₃^–-N production at a short hydraulic retention time of 1 day. Among all of the three types of pH control reagents (i.e., Ca(OH)₂, CaCO₃, and K₂CO₃), K₂CO₃ could enhance the activity of ammonium-oxidizing bacteria by raising the inorganic carbon level in the trickling filter and subsequently result in the lowest supplementation of extra macronutrients (i.e., nitrogen, phosphorus, and magnesium) to the urine-sourced nutrient solution. Batch tests showed that the highest activity of ammonium-oxidizing and nitrite-oxidizing bacteria was in the bottom compartment of the trickling filter, consistent with the vertical stratification of their relative abundance. Overall, the proposed novel concept was demonstrated to be robust and energy-efficient in nutrient recovery from real urine for hydroponics.

Bromate is a potential human carcinogen and is commonly found in water and wastewater after ozonation. Electrocatalytically, Pd has shown good activity in reducing bromate to bromide; however, the energy efficiency and cost of this technology in a realistic treatment system remain unknown. A custom filter-press reactor with minimal mass-transfer limitations was used to test the kinetics and energy consumption for bromate reduction using Pd, Ru, or Cu on activated carbon cloth as the cathode. In phosphate-buffered nanopure water at circumneutral pH, 95% of bromate was reduced to bromide (from 200 to 10 μg/L) in 1 h with a normalized activity of 2136 mL min^–1 g_Pd^–1. The total energy consumption was 0.576 kW h per gram of bromate removed, which is 9 to 43 times lower than that in reported studies. In Austin tap water (TW) at pH 9.5, the normalized activity dropped to 544 mL min^–1 g_Pd^–1, and the total energy consumption increased to 2.198 kW h per gram of bromate removed, still an improvement over all values reported in the literature despite the latter using synthetic waters. This superior performance is due to the design of the filter-press reactor that minimizes mass-transfer limitations as well as solution resistance compared to reactors evaluated in the literature, such as batch and three-dimensional electrochemical reactors. We note that any lost activity due to catalyst oxidation and poisonings in TW can be electrochemically regenerated by briefly applying a positive and strongly negative potential. This electrocatalytic treatment has estimated costs of $1.41 per 1000 gal (91% capital costs and 9% O&M costs) and is comparable to ion exchange, granular activated carbon, and reverse osmosis, yet benefits from no waste stream generation, indicating that this technology is ready for evaluation at the pilot scale.

Catalytic membranes that enable simultaneous micropollutant degradation during oil/water separation have emerged as a promising candidate for treating complex emulsified oily wastewater. However, this hybrid system suffers from membrane fouling and subsequent radical quenching. Herein, we overcome these challenges by developing a novel hierarchical filtration-catalysis ceramic membrane to achieve efficient gradient decontamination. This membrane comprises a top hydrophilic MWCNT layer deposited on a CuFe₂O₄-immobilized ceramic membrane to construct CCuFeCM. A pristine ceramic membrane (CM) and a CuFe₂O₄-immobilized membrane (CuFeCM) served as controls. Our results demonstrated that CCuFeCM presents the most alleviated fouling potential (∼18% of flux decline) and TOC removal (91%) when treating synthetic textile wastewater containing a mineral oil-in-water emulsion with RhB. Besides that, CCuFeCM achieves the highest PMS-based RhB degradation capability (100%) and initial reaction rate (0.684 min^–1). Quenching experiments and EPR analyses show that SO₄^–•, ^•OH, and ¹O₂ are responsible for the CCuFeCM/PMS oxidation system, and ¹O₂ is the dominant reactive species. The synergistic effect of oil separation and catalytic decomposition is mainly ascribed to the ordered arrangement of selective separation in advance to avoid interference with subsequent AOPs, which allows for micropollutants that are transmitted into internal membrane channels for confined catalytic oxidation. Furthermore, replication filtration tests indicate that CCuFeCM shows durable stable degradation and antifouling performance after simple cleaning. The specific functionality of oil isolation, catalyst anchor, and mass transfer effect reaction compartmentation provides a novel strategy for efficient gradient removal of multiple pollutants in water, which highlights promising application potential under realistic conditions.