Molecular composition of hydroxyl radical-resistant organics in municipal solid waste leachate.

Although hydroxyl radicals (OH) degrade organic pollutants nonselectively, their mineralization rate during the treatment of waste leachate biological treatment effluent (BTL) using Fenton or Fenton-like systems is not high, and the reason is unknown. In this study, we investigated three typical Fenton-like systems that act on dissolved organic matter (DOM) in BTL. We analyzed the molecular composition of DOM resistant to OH, using ultrahigh resolution mass spectrometry.

Molecular Characteristics and Formation Mechanisms of Unknown Ozonation Byproducts during the Treatment of Flocculated Nanofiltration Leachate Concentrates Using O and UV/O Processes.

Both ozone (O) and UV/O treatment processes can effectively remove organic matter in the flocculated membrane filtration concentrate from landfill leachate, but the ozonation byproducts (OBPs) generated in the processes remain unknown. Using electrospray ionization-coupled Fourier transform ion cyclotron resonance mass spectrometry (ESI FT-ICR MS), this study investigated the molecular characteristics of unknown OBPs and their formation mechanisms during the treatment of flocculated nanofiltration concentrate (FNFC) using the O and UV/O processes. The results showed that after being treated by the O and UV/O processes, the average value of the oxygen-to-carbon ratio (O/C) in the FNFC organic matter increased substantially from 0.

Molecular-level transformation of refractory organic matter during flocculation-ultraviolet/peroxymonosulfate treatment of MBR-treated landfill leachate.

Refractory organic matter in membrane bioreactor effluent resulting from landfill leachate treatment has a complex composition. This paper identified the transformation mechanism of organic matter in a flocculation-ultraviolet (UV)/peroxymonosulfate (PMS) system at the molecular level using electrospray ionization coupled with Fourier transform ion cyclotron resonance mass spectrometry. The results showed that the flocculation system was able to remove a large amount of dissolved organic matter (DOM) with high oxidation and unsaturation/saturation.

Transformation of dissolved organic matter in landfill leachate during a membrane bioreactor treatment.

In this study, a cutting-edge mass spectrometry (MS) technique, Orbitrap fusion MS with ultrahigh resolution, was used to analyze the molecular composition, chemical properties, formation mechanism, and environmental impact of refractory dissolved organic matter (rDOM) in leachate. The results showed that the bioavailable DOM (bDOM) and rDOM constituents varied substantially during the biological treatment of landfill leachate. Compared with bDOM, the rDOM in leachate had a higher degree of unsaturation, aromaticity, and oxidation, and a larger molecular weight, and contained more organic matter with benzene ring and biphenyl structures.

Molecular insights into the transformation of refractory organic matter in landfill leachate nanofiltration concentrates during a flocculation and O/HO treatment.

During leachate treatment, molecular information regarding the completely removed, partially removed, less-reactive, increased, and produced parts of dissolved organic matter (DOM) remains unknown. This study applied ESI FT-ICR MS to investigate the transformation characteristics of leachate nanofiltration concentrate (NFC) DOM during a combined flocculation-O/HO process. The NFC contained 5069 compounds in four main classes (CHO, CHON, CHOS, and CHONS compounds).

Microbial community response of the full-scale MBR system for mixed leachates treatment.

In practice, mature landfill leachate and incineration (young) leachate are mixed to improve the biodegradability and enhance biological treatment performance. However, the ratio of mature-to-young leachates greatly influences MBR treatment efficiency and microbial community structure. This study investigated the treatment efficiency and microbial community structure of full-scale MBR systems operated under two mix ratios, mature leachate: young leachate = 7:3 (v/v, denoted as LL) and 3:7 (v/v, denoted as IL).

The molecular differences of young and mature landfill leachates: Molecular composition, chemical property, and structural characteristic.

Landfill leachate is a highly contaminated and complex organic wastewater. It can be categorized into young (YL) and mature leachate (ML) based on the landfill age, with significant differences in the composition of organic matter, resulting from the significant differences in humification degree. To compare the organic composition of YL and ML, ESI FT-ICR MS was applied to systematically investigate their molecular composition, chemical properties, and structural characteristics.

Novel strategy for controlling colloidal instability during the flocculation pretreatment of landfill leachate.

Flocculation is an economical and effective pretreatment technology for landfill leachate. An iron salt flocculant is often used in landfill leachate pretreatment, but the flocs that are formed are affected by the operation sequence, which subsquently influences flocculation. This study selected three representative landfill leachates (i.

Microbial characteristics of the leachate contaminated soil of an informal landfill site.

Because informal landfills are not constructed in a regulated manner, they will inevitably become a source of leachate pollution to the surrounding environment over time. Microbes are an important part of the soil system, playing a vital role in maintaining the normal functionality of soil. This study investigated the microbial composition and co-occurrence pattern in the leachate contaminated soil of an informal landfill site.

Application of membrane separation technology in the treatment of leachate in China: A review.

To comprehensively investigate the application of membrane separation technology in the treatment of landfill leachate in China, the performance of nearly 200 waste management enterprises of different sizes in China were analyzed, with an emphasis on their scale, regional features, processes, and economic characteristics. It was found that membrane separation technologies, mainly nanofiltration (NF), reverse osmosis (RO), and NF + RO, have been used in China since 2004. The treatment capacity of the two most dominant membrane separation technologies, i.

Preparation of biochar and biochar composites and their application in a Fenton-like process for wastewater decontamination: A review.

Biochar is a carbon-rich material that can be obtained from pyrolysis of solid waste (e.g., agricultural solid waste and sludge from wastewater treatment plants).

A review of the characteristics of Fenton and ozonation systems in landfill leachate treatment.

The development and application of Fenton and ozonation systems in landfill leachate treatment over the last 20 years, and the current research status are reviewed in this paper, with an emphasis on the technical and economic characteristics of Fenton and ozonation systems used to treat different types of landfill leachate. To date, a total of 101 and 78 articles have been published regarding leachate treatment by Fenton and ozonation systems, respectively. These articles considered the use of two systems to treat aged leachate, biologically treated leachate and leachate comprising the concentrated solution resulting from reverse osmosis (RO).

Molecular-level insights into the transformation mechanism for refractory organics in landfill leachate when using a combined semi-aerobic aged refuse biofilter and chemical oxidation process.

Landfill leachate contains high concentrations of complex organic matter (OM) that can severely impact the ecological environment. If landfill leachate is to be treated using a combined "biological + advanced treatment" process, the molecular information of OM must be investigated to optimize the operation parameters of the combined process and maximize the removal of organic pollutants. This study applied ultra-high resolution mass spectroscopy to investigate the degradation and transformation characteristics of refractory OM in mature landfill leachate at the molecular level (m/z = 150-800) during biological treatment (i.

A pilot-scale comparative study of bioreactor landfills for leachate decontamination and municipal solid waste stabilization.

Many studies have sought to optimize operation parameters and enhance the treatment capacity of bioreactor landfills (BL) under ideal laboratory conditions. At pilot scale, conclusions drawn from laboratory-scale experiments will be different due to variations in actual landfill composition and changes in environmental conditions. However, comparative pilot-scale studies of traditional anaerobic landfills (AnL) and BLs are rare.

Recovery of efficient treatment performance in a semi-aerobic aged refuse biofilter when treating landfill leachate: Washing action using domestic sewage.

Semi-aerobic aged refuse biofilters (SAARB) are known to efficiently remove organic matter, nitrogenous substances, and anions from landfill leachate. However, long-term recirculation of mature landfill leachate inevitably leads to accumulation of pollutants and decreases treatment capacity. In this study, the washing action provided by domestic sewage was used to recover and even enhance the treatment performance of SAARBs treating mature landfill leachate.

Improved oxidation of refractory organics in concentrated leachate by a Fe-enhanced O/HO process.

Concentrated leachate from membrane processes, which contains a mass of refractory organics and salt, has become a new problem for wastewater engineers. In this study, removal of organic contaminants in concentrated landfill leachate was investigated by applying the ferrous ion (Fe) catalyzed O/HO process. The maximum chemical oxygen demand (COD) and absorbance at 254 nm (UV) removal efficiencies under the optimal conditions (initial pH = 3.

Comparison study on microwave irradiation-activated persulfate and hydrogen peroxide systems in the treatment of dinitrodiazophenol industrial wastewater.

In this study, refractory organics in industrial wastewater containing dinitrodiazophenol (DDNP) were treated by microwave (MW) irradiation-activated persulfate (PS) and hydrogen peroxide (HO). The organics degradation effect of MW output power, oxidant dosage and initial pH were investigated. Spectral analysis and radical scavenging experiments were used to investigate the degradation pathway and identify reactive oxygen species in the two systems.

Dinitrodiazophenol industrial wastewater treatment by a sequential ozone Fenton process.

The ozonation process is efficient in degrading aromatic substances and substances with unsaturated bonds, but cannot effectively destroy small-molecule organic compounds, which accumulate. Likewise, the Fenton process is a classic wastewater treatment method, but requires strict pH control and produces secondary pollution when the concentration of organic substances is high. In this study, we applied a 1stO-2ndFenton sequential process to treat diazodinitrophenol (DDNP) industrial wastewater and provide suitable reaction conditions for Fenton process.

Degradation of refractory organic contaminants in membrane concentrates from landfill leachate by a combined coagulation-ozonation process.

Landfill leachate is a typical refractory wastewater for which research into rapid and efficient treatment methods has become very topical. In this study, a coagulation-ozonation process was developed to treat the concentrate arising from membrane treatment of landfill leachate. The effect of coagulant type and initial pH on treatment efficiencies was investigated.

Kinetics study of dinitrodiazophenol industrial wastewater treatment by a microwave-coupled ferrous-activated persulfate process.

In this study, a ferrous-activated persulfate (PS) process induced by microwave (MW) energy was used to treat an industrial wastewater containing dinitrodiazophenol (DDNP). The effect of different operational parameters, such as PS dose, initial pH, MW power, and the mass ratio of ferrous to PS [i.e.

Mechanism of adsorption of humic acid by modified aged refuse.

In the present study, aged refuse (AR) was modified to be applied as an adsorbent to remove humic acid from water. The efficiency of humic acid removal by modified aged refuse (MAR) under different preparation conditions (calcination temperature, dose of aged refuse for calcination and holding time) was systematically investigated. Results showed that the optimum preparation conditions are calcination temperature = 700 °C, AR dose for calcination = 25 g, and holding time = 2.

Degradation of recalcitrant organics in landfill concentrated leachate by a microwave-activated peroxydisulfate process.

A microwave (MW)-activated peroxydisulfate (PDS) process was applied to remove recalcitrant organics in concentrated leachate. In this study, the optimum activation conditions were studied using the absorbance at 254 nm (UV) and color number removal efficiencies and by comparison of the different processes. The inner oxidation mechanism was investigated by ultraviolet-visible (UV-vis) spectrophotometry and three-dimensional (3D) excitation-emission matrix (EEM) tests.

Removal of refractory organic pollutants in reverse-osmosis concentrated leachate by Microwave-Fenton process.

A microwave-Fenton technology was applied to dispose of the reverse-osmosis concentrated leachate. Influential factors on the treatment of concentrated leachate with the pure Fenton and microwave-Fenton method were investigated. For the conventional Fenton process, the removal efficiencies of chemical oxygen demand (COD), UV, and the color number (CN) reached 84%, 87%, and 96%, respectively, with the biodegradability (BOD/COD) increased from 0.

Treatment of dinitrodiazophenol industrial wastewater in heat-activated persulfate system.

Heat-activated persulfate oxidation process was investigated as the treatment of dinitrodiazophenol industrial wastewater to degrade refractory pollutants and improve biodegradability. By studying the effects of 4 factors and carrying out orthogonal tests and scale-up experiments, optimal treatment conditions (temperature 90 °C, reaction time 75 min, PS dosage 20.0 g L and initial pH ∼2.