Zhongfang Lei

University of Tsukuba · School of Life and Environmental Sciences

Severe effects of water pollution would need to be addressed by utilizing advanced water and wastewater treatment. Due to globalization, organic dyes and emerging contaminants are significant water pollutants that can bring harm to humans and the environment. Nevertheless, conventional treatment is not suitable for removing these pollutants. Photoc...

A lab-scale photo bio sequencing batch reactor (PSBR) was used to develop microalgal-bacterial aerobic granular sludge (MB-AGS) for old leachate treatment by seeding activated sludge, while indigenous microalgae were allowed to grow naturally. Upon 100 days of experiment, mature MB-AGS was successfully developed with an average diameter of 2.5 ± 1....

This study focused on the effect of hydrothermal (HT) treatment at 180 – 210 °C for holding 0 - 15 min on the solubilization of rice straw and the changes of HT residue. The optimum treatment conditions for the highest solubilization and solid reduction of rice straw was 210 °C for holding 0 min. Under this condition, the extraction yield and total...

Reducing CO2 emission and energy consumption is crucial for the sustainable management of wastewater treatment plants (WWTPs). In this study, an algal-bacterial aerobic granular sludge (AGS) system was developed for efficient carbon (C) assimilation and nitrogen (N)/phosphorus (P) removal without the need for mechanical aeration. The photosynthetic...

Extracting alginate-like exopolymers (ALE) is a promising approach for valuable resources recovery from excess algal-bacterial aerobic granular sludge (AGS) to achieve circular bioeconomy and environmental sustainability in wastewater treatment plants (WWTPs). In this study, six batch cultivation tests were conducted to investigate the optimal cult...

Limited information is available on the characteristics of algal-bacterial aerobic granular sludge (AGS) treating real wastewater, especially on its alginate-like exopolymers (ALE) production. In addition, the effect of target microalgae species inoculation on the system performance has not been fully understood. This study aimed to reveal the effe...

Molybdenum pollution in groundwater is drawing increasing attention since high levels of molybdenum have been detected worldwide, including in the United States, China, and Mongolia. Although molybdenum is considered an essential element for all living organisms, exposure to high levels of molybdenum may result in disorders of the gastrointestinal...

Antibiotic resistance genes can be spread via gene horizontal transfer (GHT). Chlorination and UV irradiation are common disinfection methods used in wastewater treatment plants before the discharge of treated wastewater. This study aimed to elucidate the effects of disinfection on the transformation of naked DNA in the aquatic environment. The pUC...

High value-added products recovery from algal-bacterial granular sludge (ABGS) has received great attention recently. This study aimed to explore the role of different light wavelengths in regulating granule formation, protein and lipid production, and microbial functions. Bacterial granular sludge (BGS, R0) was most conducive to forming ABGS under...

Farmlands fertilized with livestock manure-derived amendments have become a hot topic in the dissemination of antibiotic resistance genes (ARGs). Field ponding water connects rice paddies with surrounding water bodies, such as reservoirs, rivers, and lakes. However, there is a knowledge gap in understanding whether and how manure-borne ARGs can be...

The microalgae-based wastewater treatment technologies are believed to contribute to carbon neutrality. This study investigated the inorganic carbon fixation performance in the algal-bacterial aerobic granular sludge (A-BAGS) process under cultivation at different concentrations of organic carbon (OC) and inorganic carbon (IC). The results indicate...

Despite various research works on algal-bacterial aerobic granular sludge for wastewater treatment and resource recovery processes, limited information is available on its application in real wastewater treatment in terms of performance, microbial community variation and resource recovery. This study investigated the performance of algal-bacterial...

Among the common treatment/disposal routes of excessive activated sludge from municipal wastewater treatment plant, dewatering process functions as an essential pre-/post-treatment for volume minimization and transportation facilitation. Since inorganic coagulants have long been criticized for their high dosage and solid residue in sludge cake, the...

This study investigated the biological nitrogen removal mechanisms during the anaerobic digestion of swine manure and the effects of biogas circulation and activated carbon (AC) addition. Biogas circulation, AC addition, and their combination increased the methane yield by 25.9%, 22.3%, and 44.1%, respectively, when compared to the control. Nitroge...

Heavy metal ions such as Cr(VI) leaching from agricultural soil is one of the significant environmental pollution threats. Hydrochar from hydrothermal co‑carbonization (HtcoC) of digested sewage sludge (DSS) and rice straw (RS) shows excellent adsorption potential of Cr(VI). Still, its stability at soil pH change is not well understood. This study...

Fe3O4 addition in anaerobic fermentation of food waste (FW) is promising for enhancing volatile fatty acids (VFAs) production. However, the large amount of Fe3O4 in the digestate fertilizer leads to the waste of resources and possible toxicity to organisms. Thus, this study investigated the feasibility of Fe3O4 recycling for VFAs enhancement in ana...

This study was conducted to observe the possibility of long-term storage of aerobic granular sludge (AGS) for further purposes. The research was done by drying the AGS and then stored in zip-lock bags placed in the laboratory and storage room. The AGS stored for 1 day in the laboratory, 1 week, and 1 month in both locations. The AGS then reactivate...

An increasing attention has been paid to the secure and sustainable management of agricultural wastes, especially lignocellulosic biomass. Nanobubble water (NBW) contains 106-108 bubbles/mL with diameter <1000 nm. Although previous studies have examined the enhancement effects of NBW on methane production from organic solid wastes, the NBW-based an...

Calcium ions (Ca2+) are important for biological phosphorus (P) removal from wastewater, but its behavior has not been well documented during the anaerobic P release process. This study is aimed to explore the mechanisms of Ca2+ release in bacterial aerobic granular sludge (AGS) system. During the non-aeration (anaerobic) phase, nearly 40% increase...

Zero-valent iron (ZVI) supplementation for enhancing anaerobic digestion (AD) of swine manure (SM) has been widely studied. However, the low utilization efficiency of ZVI in AD process greatly limits the development of this technology. In this study, a promising approach, biogas circulation was proposed to promote ZVI dissolution during AD. Compare...

Lead (Pb) discharged from rural industries poses a significant threat to the environment and human health. Algal-bacterial aerobic granular sludge (A-B AGS) is a promising alternative for sewage treatment with high efficiency and good settleability. In this study, Pb(II) biosorption using fresh A-B AGS was investigated for the first time. The impor...

This study presents a rapid method on how to speed up aerobic granular sludge (AGS) cultivation and ensure excellent and stable removal performance during bioreactor operation for domestic wastewater treatment. This new strategy consists of start-up the bioreactor using only anaerobic granular sludge (AnGS) as a seed and feeding with crude sewage e...

The public health concern of wastewater treatment spans many centuries and civilizations. The most significant advancement and evolution of wastewater treatment in the last century is the advent of conventional activated sludge (CAS) process to bacterial and/or algal-bacterial aerobic granular sludge (AGS) systems. This research is aimed to overvie...

Manuscript Submission Deadline 30 October 2022 With the fast-evolving global climate change, increasing efforts have been devoted to the mitigation of greenhouse gases (GHGs) emission from municipal wastewater treatment plants where, in fact, they have been found to be an important source of GHGs. It should be aware that the carbon taxing and trad...

High treatment capacity for food waste (FW) is required due to the huge amount generated worldwide. Conversion of FW to volatile fatty acids (VFAs) via anaerobic fermentation is a promising technology; however, inhibition of VFAs production could easily occur at high loadings. In this study, Fe3O4 was used to enhance VFAs production in anaerobic fe...

The energy-consuming and carbon-intensive wastewater treatment plants could become significant energy producers and recycled organic and metallic material generators, thereby contributing to broad sustainable development goals, the circular economy, and the water-energy-sanitation-food-carbon nexus. This review provides an overview of the waste(wat...

Consumers often complain about taste and odor (T&O) in drinking water and freshwater fishery. One of the common T&O compounds, 2-methylisoborneol (2-MIB), can be detected by humans even when the concentration is below 10 ng/L. A forecast method of T&O occurrence is required to control drinking water plants and fishery farms to determine the timing...

Geosmin, produced by cyanobacteria and actinomycetes, is a common cause of earthy odor in lakes, rivers, and reservoirs. Drinking water quality standards in Japan requires that geosmin concentration be maintained at < 10 ng/L. The concentration of musty/earthy odor compounds in water bodies tends to exhibit a positive correlation with the cell dens...

A reasonable recovery of excess sludge may shift the waste into wealth. Recently an increasing attention has been paid to the recycling of extracellular biopolymers from conventional and advanced biological wastewater treatment systems such as flocculent activated sludge (AS), bacterial aerobic granular sludge (AGS), and algal-bacterial AGS process...

In this study, we have examined a new all-organic conditioning method for sewage sludge pretreatment, featuring the combined use of poly dimethyldiallylammonium chloride (PDMD) and tannic acid (TA). The impact of the reagents and the specific dosing order were identified for process optimization. Results showed that TA + PDMD mode (i.e., TA additio...

Fe3O4 supplementation has been reported as a high-efficient approach to enhance biogas production in anaerobic digestion (AD). Volatile fatty acids (VFAs), especially acetic acid (HAc), are considered as important products in acidification process of AD. However, the possible mechanisms involved in promotion effect of Fe3O4 on HAc production in hyd...

Nitrous oxide (N2O) emitted from wastewater treatment processes has emerged as a focal point for academic and practical research amidst pressing environmental issues. This review presents an updated view on the biological pathways for N2O production and consumption in addition to the critical process factors affecting N2O emission. The current rese...

The novel type of microalgae granules (MGs) derived from tiny microalgae cells has received extensive attention due to its great potential for nutrient remediation and resource recovery in wastewater treatment whereas the long start-up time with increased labor expenses remains a bottleneck. In this study, an operation strategy at reduced upflow ai...

Feammox process is crucial for the global nitrogen cycle and has great potentials for the treatment of low COD/NH4⁺-N wastewaters. This work provides a systematic and comprehensive overview of the Feammox process. Specifically, underlying mechanisms and functional microbes mediating the Feammox process are summarized in detail. And key influencing...

Liquid nitrogen was employed as a low-temperature medium to activate zero-valent iron (ZVI) powder in an attempt to strengthen its enhancement effect on anaerobic digestion (AD) of swine manure (SM). Surprisingly, it was found that both pristine ZVI and liquid nitrogen-pretreated ZVI (LZVI) did not significantly improve the AD performance or change...

This study investigated the effects of microalgae growth on antibiotic removal and the attenuation of antibiotic resistance genes (ARGs)/ARGs host bacteria in algal-bacterial granular sludge (ABGS) system. In the presence of tetracycline (TC) and sulfadiazine (SDZ) mixture (2-4 mg/L), microalgae could grow on bacterial granular sludge (BGS) to form...

The effects of organic loading rate (OLR) on simultaneous phosphorus (P) and alginate-like exopolymers (ALE) recovery from bacterial aerobic granular sludge (AGS) and algal-bacterial AGS were examined and compared during 70 days’ operation. With the increase of OLR (0.6 - 1.2 g COD/(L·day)), both AGS showed good settleability and granular strength...

This study aimed to figure out the main contributors to aerobic phosphorus (P) removal in the algal-bacterial aerobic granular sludge (AGS)-based wastewater treatment system. Kinetics study showed that aerobic P removal was controlled by macropore (contributing to 64 -75% P removal) and micropore diffusion, and the different light intensity (0, 4.0...

Cr(VI) is among the most hazardous heavy metals with high toxicity in acidic soil. This study for the first time examined the solid form Cr(VI) remediation by hydrochar from hydrothermal co‑carbonization (HTcoC) of rice straw (RS) and digested sewage sludge (DSS) and evaluated its soil conditioner potentials. Results indicated that hydrochar produc...

Recently, increasing interest has been placed in microalgal-bacterial granular sludge (MBGS) in the journey towards the energy and carbon neutrality of municipal wastewater treatment. Different from aerobic granular sludge, the performance of MBGS is mainly determined by the mutualism and symbiosis between coexisting microalgae and bacteria. It app...

Algal-bacterial aerobic granular sludge (AGS) was applied for hexavalent chromium (Cr(VI)) biosorption from wastewater and the dynamic distribution and mobility of different metals in granules were systematically examined before and after hydrothermal treatment. The loaded Cr on algal-bacterial AGS was found to mainly localize in microbial cells an...

Energy self-sufficient wastewater treatment designs can reduce net energy consumption and achieve resources recovery. Microalgae are regarded as a promising candidate for developing a circular bioeconomy in wastewater treatment plants (WWTPs) due to its potential for simultaneous wastewater remediation and high value-added materials production. Muc...

Algal-bacterial aerobic granular sludge (AGS) as a promising wastewater treatment biotechnology has attracted more attention in recent years. Still, limited information is available on the effect of stepwise illumination on algal-bacterial AGS. In this study, two illumination strategies, i.e., stepwise (R1) and one-time (R2) daily, were applied to...

Microalgal-bacterial aggregates (MABAs) have the potential to self-sustain their gas usage. By introducing O2 from microalgae to bacteria, and supplying CO2 the opposite way, ideally the gas can be circulating within the system and no external aeration is needed if other factors, like illumination and nutrients, are not limiting the growth of each...

This research focused on the impacts of environmental policies on the conservation and improvement of urban river water quality in Mongolia. Wastewater contaminated by heavy metal (chromium) from the thriving tanning industry has been recognized as a problem in Ulaanbaatar, the capital of Mongolia, and a facility for pretreatment of chromium-contam...

Given that long-term treated wastewater discharge may alter the microbial community of the recipient coast, it is important to evaluate whether and how the community's stability is impacted. We constructed microcosms using coastal sediments with (near-coast) and without (far-coast) a wastewater disposal history and compared the communities’ respons...

A synergistic process was proposed to prepare hydrochar by hydrothermal co-carbonization (HTcoC) of waste distillers grains with sewage sludge, focusing on hydrochar properties and combustion behavior under different mixing ratios. Results show that the co-hydrochar from HTcoC exhibited excellent synergistic characteristics with relatively high syn...

Alkaline-thermal pretreatment was examined for waste activated sludge (WAS) disintegration and subsequent anaerobic digestion (AD). Pretreatment at 60 °C was estimated to provide better economic benefits than higher temperature conditions. The maximum methane yield of 215.6 mL/g COD was achieved when WAS was pretreated at 60 °C and pH 10 for 24 h,...

Anaerobic digestion has been recognized as promising technology for bioenergy production, while the bottlenecks including long start up times, low methane contents, and susceptibility toward environmental change attenuate the process benefits. Integrating microbials electrolysis cell (MEC) with anaerobic digestion (AD) has been recognized as a prom...

Air-nanobubble water (NBW) was applied to pre-acclimate anaerobically digested sludge that was then used as the inoculum in the two-stage anaerobic digestion (AD) of high saline (20 g NaCl/L) food waste (FW) to optimize NBW application in the AD of high saline FW. K⁺ was simultaneously supplemented during the methanogenic stage to resist the inhibi...

Biogas upgrading is an essential process for efficient and safe utilization of biogas produced from anaerobic digestion (AD), a cost-effective and environmentally friendly technology for bioenergy recovery from organic wastes. Biogas recirculation in AD reactors has been recently reported as a cost-effective and promising method to enhance methane...

Wastewater treatment plants are expected to realize not only pollutants removal from wastewater but also resources recovery such as phosphorus (P) and alginate-like exopolysaccharides (ALE) from the produced sludge. In this study, ALE extraction and fractionation from the same activated sludge-derived bacterial aerobic granular sludge (AGS) and alg...

In order to sustainably manage wastewater treatment plants and the environment, enhanced biological phosphorus (P) removal (EBPR) was proposed to achieve P recovery through extracting P-rich liquid (i.e., Phostrip) from the bottom of aerobic granular sludge (AGS)-based sequencing batch reactors (SBRs) under no mixing during the anaerobic phase. Res...

Combined effect of zero valent iron (ZVI) and magnetite on semi-dry anaerobic digestion of swine manure was studied. Compared with control, the addition of 5 g/L ZVI, magnetite and their mixture (1:1 wt.) increased the CH4 yield by 17.6%, 22.7% and 21.9%, respectively. The three additives improved CH4 production through altering the metabolism path...

Toxic cyanobacterial blooms frequently develop in eutrophic freshwater bodies worldwide. Microcystis species produce microcystins (MCs) as a cyanotoxin. Certain bacteria that harbor the mlr gene cluster, especially mlrA, are capable of degrading MCs. However, MCs-degrading bacteria may possess or lack mlr genes (mlr+ and mlr− genotypes, respectivel...

Cyanobacterial blooms accompanied by taste and odor (T&O) compounds affect the recreational function and safe use of drinking water. Geosmin and 2-methylisoborneol (2-MIB) are the most common T&O compounds. In this study, we investigated the effect of temperature on geosmin and 2-MIB production in Dolichospermum smithii and Pseudanabaena foetida va...

This study investigated the possibility of biogas recirculation-driven anaerobic granular sludge system for sewage sludge treatment, aiming to develop an energy sufficient and multifunctional anaerobic digestion (AD) system for sewage sludge with biogas upgrading, sludge stabilization and self-aggregation. Results show that biogas recirculation cou...

Anaerobic digestion of decabromodiphenyl ether was carried out and compared in two continuously stirred anaerobic bioreactors for 210 days under thermophilic and mesophilic conditions. Results show that the degradation of decabromodiphenyl ether followed the first-order reaction kinetics, which exhibited a higher removal rate in the thermophilic re...

Biomass harvesting is the bottleneck for microalgae-based technologies in practical application for simultaneous wastewater remediation and resource recovery. Biogranulation has been proven to possess high potentials for cost-effective microalgae cultivation and harvesting, while the long start-up duration (about several months) is challenging its...

Heavy metal-containing wastewater with high salinity challenges wastewater treatment plants (WWTPs) where the conventional activated sludge process is widely applied. Bioremediation has been proven to be an effective, economical, and eco-friendly technique to remove heavy metals from various wastewaters. The newly developed algal-bacterial aerobic...

Anaerobic digestion (AD) is an effective biological process to recover energy from organic solid wastes. There is a growing interest in utilization of renewable or sustainable bioenergy sources as future alternatives to fossil fuels. However, low hydrolysis rate, high heterogeneity of plant cell-wall structure of lignocellulose, process instability...

Cobalt Hexacyanoferrate (CoHCF) was tested for the selective uptake of K from seawater and the electrochemical method was adopted for the desorption and regeneration of the material. Powder form CoHCF could adsorb about 6.5 mmol/g of K from the seawater. For the ease of the electrochemical desorption and regeneration, CoHCF thin film was coated ont...

The wastewater in the mining usually was contaminated by multi heavy metals. Low-cost, multi targets, sufficient capability, good reusability are always the first considerations for adsorbents. In this study, a unique plateau laterite ceramic (PLC) made from a characteristic clay soil naturally containing rich Fe and Al ions was used to simultaneou...

In this study, chromium (Cr) was used as an example of the most toxic heavy metals that threaten human health, and Cr(VI) bioremediation was implemented by using a new type of aerobic granular sludge (AGS), i.e., algal-bacterial AGS. Results showed that the total Cr removal efficiency by active algal-bacterial AGS was 85.1±0.6% after 6 h biosorptio...

Most previous studies have focused on the effects of salt on anaerobic digestion (AD) for hydrogen or methane production. However, the effects of salt on two-stage AD and related approaches to mitigate the adverse effects of high salinity on hydrogen and/or methane production were seldom addressed. In this study, addition of Air-nanobubble water (A...

Resistant pollutants like oil, grease, pharmaceuticals, pesticides, and plastics in wastewater are difficult to be degraded by traditional activated sludge methods. These pollutants are prevalent, posing a great threat to aquatic environments and organisms since they are toxic, resistant to natural biodegradation, and create other serious problems....

Cordyceps militaris possesses several compounds with medicinal properties, and is commonly used in traditional Chinese functional food and medicine for a variety of health benefits. Because of its rare occurrence in nature, the market demand for artificial C. militaris is on the rise. Furthermore, efforts to increase its bioactive ingredients have...

Wastewater treatment plants are particularly challenging with the treatment and disposal of sewage sludge produced from the treatment units due to its high costs and environmental hazards. In this study, a biogas recirculation-driven AD system was developed with upward shear force being provided by biogas recirculation coupled with the alkali addit...

Anaerobic digestion (AD) of ammonia-rich swine manure (SM) with nano-bubble water (NBW) supplementation was studied in this work with the expectation of ammonia inhibition alleviation, buffering capacity promotion, and methane production enhancement. Results indicated that cumulative methane yield was elevated by 12.3-38.7% in NBW groups. Besides,...