Publications by authors named "Kewu Pi"

Soil, food, and clean water are essential resources for sustaining human society and preserving ecological balance. However, the growing challenges of soil salinization and freshwater scarcity increasingly threaten global agricultural productivity and environmental health. This work presents an innovative Wash-Evaporate-Irrigate (WEI) system that integrates saline soil remediation, solar-powered freshwater recovery, salt resource harvest, and agricultural irrigation into a cohesive and sustainable process.

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Cyanobacterial blooms are prevalent globally and present a significant threat to water security. Titanium salt coagulants have garnered considerable attention due to their superior coagulation properties and the absence of metal residue risks. This paper explored the influencing factors in the coagulation process of titanium xerogel coagulant (TXC), the alterations in cell activity during floc storage, and the release of cyanobacterial organic matters, thereby determining the application scope of TXC for cyanobacterial water treatment.

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Article Synopsis
  • - The study explores the electroreduction of toxic chromium (Cr(VI)) in wastewater, where it transforms into less harmful chromium (Cr(III)) through precipitation on the cathode during electrochemical reactions.
  • - Common inorganic anions like nitrate, chloride, phosphate, and sulfate were found to influence this electroreduction process, with sulfate being the most effective at enhancing Cr(VI) reduction but impeding Cr(III) precipitation.
  • - Experimental results showed that the presence of sulfuric anions significantly boosted the reduction efficiency of Cr(VI) (up to 99.9%) at certain concentrations, while lower concentrations of nitrate led to higher total chromium removal (92.8%), highlighting the complex interactions in wastewater treatment
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FHWSB as an integrated absorptive catalyst, based on Walnut shell biochar (WSB) via hydrochloric acid modification and ferrous chloride impregnation, was prepared, reacted with HO to generate active free radicals •OH and •O, which oxidized and degraded about 80% of micro-pollutant sulfamethoxazole (SMX) from water, effectively resolving micro-pollutants' removal being inefficient because of high toxicity, persistence, and bioaccumulation in existed methods. It was clarified the specific degradation pathways and mechanisms of SMX by FHWSB synergistic HO via characterization and analysis assisted DFT calculations. Furthermore, it was found that the toxicity of a series of intermediates produced by SMX degraded continued to decline, consistent with its direction of degradation via toxicological analysis.

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Activated persulfate and hydrothermal treatment (HTT) are often employed to treat waste activated sludge, which can improve the efficiency of subsequent sludge treatment and change the distribution of pollutants in the sludge. However, the impact of sludge solid content and temperature on the occurrence and aging of microplastics (MPs) during HTT remains poorly understood. This study investigated the effects of persulfate-HTT (SPS-HTT) co-treatment on the migration, occurrence, and aging of MPs in sludge with different solid contents (2% and 5% solid content).

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Eutrophication, the over-enrichment with nutrients, for example, nitrogen and phosphorus, of ponds, reservoirs and lakes, is an urgent water quality issue. The most notorious symptom of eutrophication is a massive proliferation of cyanobacteria, which cause aquatic organism death, impair ecosystem and harm human health. The method considered to be most effective to counteract eutrophication is to reduce external nutrient inputs.

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Article Synopsis
  • Pb soil pollution is a significant health risk, and the most common cleanup method is immobilization, which prevents heavy metals from moving in the soil.
  • A study used municipal sewage sludge to treat Pb-contaminated soils from a lead-acid battery factory, reducing leachable Pb levels significantly over time, with the addition of phosphate fertilizer further enhancing this effect.
  • The remediation process significantly decreased the bioavailability of Pb in plants, with results showing a reduction of Pb absorption in mung bean roots by 87%, attributed to changes in how Pb interacts with soil components during treatment.
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The potential for the presence of microplastics (MPs) in municipal solid waste incineration bottom ash (MSWI-BA) has not been fully explored. In this study, surfactant-assisted air flotation separation in aqueous media was used to examine the removal of MPs and other pollutants from different particle size fractions of MSWI-BA. The use of 1 mmol L sodium dodecylbenzene sulfonate (SDBS), at a liquid-solid ratio of 60:1, increased by 66 % the quantity of MPs floated from the MSWI-BA 0-0.

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Soil heavy metal pollution poses a serious threat to the eco-environment. Municipal sludge-based passivators and clay minerals have been widely applied to immobilize heavy metal contamination in soils. However, little is known about the immobilization effect and mechanisms of raw municipal sludge and clay in reducing the mobility and bioavailability of heavy metals in soils.

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Due to the increasing use of antibiotics, tetracycline was frequently detected in wastewater. As a novel technology, algal-bacterial granular sludge process is expected to be widely used in wastewater treatment. However, the degradation effect of tetracycline by algal-bacterial granular sludge process and its degradation path is still unknown.

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The immobilization of heavy metal pollutants in river and lake sediments is critical for environmental health and safety. In this study, combined electrokinetic and chemical immobilization were used to remediate Cd and Pb polluted river sediments. The effect of the concentrations of the immobilization reagents and the applied voltage were investigated.

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Waste activated sludge and food waste are two typical important domestic low-value organic solid wastes (LOSW). LOSW contains significant organic matter and water content resulting in the transboundary transfer of liquid-solid-gas and other multi-mediums, such that the complexity of microplastics (MPs) migration should be of greater concern. This article provides a review of the literature focusing on the separation and extraction methods of MPs from LOSW.

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Sewage treatment plants act as both sinks and sources of microplastics with elevated concentrations of microplastics accumulating in the sludge. Consequently, the effects of sludge conditioning and dewatering processes on the fate of microplastics need to be clarified. Microplastic characteristics in sludge, before and after advanced oxidation Fe(II)-activated persulfate conditioning were studied using a microplastics dynamic flotation separator (MDFS).

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Microplastics are frequently detected in wastewater treatment plants, but the knowledge of their effects on microalgal-bacterial granular sludge (MBGS) is still unknown. This study investigated the performance and adaptive response of MBGS exposed in municipal wastewater in the presence of polystyrene (PS) microplastic particles with different sizes (i.e.

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Heavy metals and metalloids, in sludge and sediments, are environmental pollutants of concern with long-term negative effects on human and ecological health. In this study, sludge from biological treatment of municipal waste leachate was pyrolyzed into leachate sludge-derived biochar (LSDB) at 300°C to 900°C, comprising complex organic and inorganic (particularly heavy metals) species formed from heterogeneous chemical reactions. Based on different advanced material analyses, that is, Thermogravimetric Analysis (TGA), Fourier transform infrared (FTIR), scanning electron microscopy (SEM), and X-ray diffraction (XRD) analysis, this study revealed that mass loss and microstructural changes of LSDBs occurred primarily due to decomposition of volatiles, aromatic rings, carbonates, and hydroxides.

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Sludge conditioning is important for improved dewatering, with the sludge characteristics impacting the effect of conditioning. A composite conditioner, Fe-activated sodium persulfate (Fe/SPS) combined with phosphogypsum (PG), was used to examine its impact on sludges with different organic contents (34.6-43.

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Disposal of dredged river sediment requires decreases in both water content for reduction in disposal area, and the amount of eutrophication pollutants at risking of leaching. The effects of CaCl, polyferric sulfate (PFS) and calcified polyferric sulfate (CaPFS) on dewatering and phosphorus immobilization were examined. Upon CaPFS dosage of 1.

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Artificial top-to-bottom water transmitting channels made of threads of wool blend (WT), cotton (CT), flax (FT), and polyethylene (PET) were used to enhance the dewater efficiency for river sediment. In addition, the disordered channels composed of 3-mm-long WT segments mixed randomly into the river sediment were also employed. The most effective dewatering channels were found to be top-to-bottom WT channels with water absorption capacity of 8.

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Chemical conditioning is an effective strategy for improved river sediment dewatering affecting both the dewatering efficiency and subsequent resource utilization of the dewatered cake. Two types of conditioning agents, polyaluminium chloride (PAC)/cationic polyacrylamide (PAM) (coagulation precipitation conditioning agent, referred to as P-P conditioning) and ferrous activated sodium persulfate (advanced oxidation conditioning agent, referred to as F-S conditioning) were examined. With increasing leach liquid to solid (L/S) ratio the concentration of Cd for the real time leachates from the dewatered cakes decreased, but the leaching ratio of Cd in both P-P and F-S dewatered cakes increased.

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Electro-dewatering (EDW) is an emerging technology for improved sludge/sediment dewatering enabling subsequent cost effective treatment for toxicity and pathogenic reduction if required and/or disposal, but the effects of sediment/sludge properties on the efficacy of EDW remain unclear. Here we investigate EDW in the absence of chemical conditioning which can result in secondary pollution. The influence of sediment/sludge volatile solids content (VS), electrical conductivity (EC), pH and zeta potential (ζ), on mechanical and electrical behaviors determining dewaterability and energy consumption (P) was investigated.

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Traditional water treatment plants adopt multiple treatments to sequentially treat raw water for producing potable water. Besides complex treatment design and operation, they typically require a large space to accommodate different reactors. Furthermore, emerging issues (e.

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A series of electro-dewatering experiments were conducted to explore the effect of sediment cake thickness (1-5 cm) and electric field strength (2-50 V cm). The final dry solids content, energy consumption and dewatering productivity were modeled and the validity of the model was tested. It was demonstrated that the electric field strength determines final dry solids content and the power utilization is an exponential function of electric field strength.

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Article Synopsis
  • Researchers studied ways to remove calcium (Ca) and recover magnesium (Mg) from wastewater produced during flue gas desulfurization (FGD).
  • They examined several chemical additives and found that oxalate was much more effective than carbonate for separating Ca from Mg, achieving a 96% removal rate of Ca at a pH of 6.0.
  • The recovery of Mg was successfully done using sodium hydroxide (NaOH) in a two-step process, resulting in a highly pure magnesium hydroxide (Mg(OH)₂) product with a purity of 99.3 wt.%.
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