Xinmin Zhan

• Ollscoil na Gaillimhe – University of Galway

Animal manure is considered to have great potential for phosphorus (P) recovery due to its high P content, while P recovery is limited by the transfer of P from the solid phase to the liquid phase. The conventional dissolution process by adding chemical acid reagents is not economically feasible for animal manure. This study used food waste (FW) as...

Autotrophic denitrification utilizing iron sulfides as electron donors has been well studied, but the occurrence and mechanism of abiotic nitrate (NO3–) chemodenitrification by iron sulfides have not yet been thoroughly investigated. In this study, NO3– chemodenitrification by three types of iron sulfides (FeS, FeS2, and pyrrhotite) at pH 6.37 and...

Pasture-based beef systems can provide cattle slurry and grass silage for anaerobic digestion (AD). However, sustainable production of these feedstocks within a livestock farm presents challenges. This study examined the farmland area required to provide slurry and grass silage for a 40 GWh biomethane plant, quantified greenhouse gas (GHG) emission...

Antimicrobial resistance (AMR) is recognised worldwide as one of the greatest threats to human health. Often referred to as the silent pandemic, AMR not only impacts on human health but has major implications for our animals, food production systems, environment and economy. The One Health concept recognises that the health of humans, animals and o...

Mathematical modeling of anaerobic digestion is a powerful tool to predict gas yields and optimize the process. The Anaerobic Digestion Model No. 1 (ADM1) is a widely implemented model for this purpose. However, modeling full-scale biogas plants is challenging due to the extensive substrate and parameter characterization required. This study descri...

Nutrient recovery from anaerobic digestate through electrodialysis technology (ED) has been investigated and shown high promise, but the removal of 17β-estradiol (E2), which is a natural estrogen and widely found in manure digestate, is not clear. This study examined the mechanism of membrane adsorption and anodic oxidation of E2 during recovering...

Iron sulfides-based autotrophic denitrification (IAD) is effective for treating nitrate-contaminated wastewater. However, the complex nitrate transformation pathways coupled with sulfur and iron cycles in IADs are still unclear. In this study, two columns (abiotic vs biotic) with iron sulfides (FeS) as the packing materials were constructed and ope...

Struvite recovered from wastewater contains high concentration of fecal indicator bacteria (FIB), porcine adenoviruses (PAdV) and antibiotic resistance genes (ARGs), becoming potential resources of these microbial hazards. Understanding the precipitation behavior of pathogenic indicators and ARGs with suspended solids (SS) will provide the possible...

Composting experiment of swine manure, adding with yellow phosphorus slag(YPS) at 5% (w/w), was conducted in an industrial-scale reactor covered with semi-permeable membrane. During 27 days of composting, the changes in temperature, compost quality and phosphorus(P) speciation of products were monitored. Results indicated that the temperature of co...

Struvite production can recover ammonia and phosphorous from digested wastewater as fertilizer. During struvite generation, most of the heavy metals was co-precipitated with ammonia and phosphorous into struvite. Understanding the precipitation behavior of heavy metals with suspended solids (SS) might provide the possible strategy for the control o...

Iron sulfides-based autotrophic denitrification (IAD) is a promising technology for nitrate and phosphate removal from low C:N ratio wastewater due to its cost-effectiveness and low sludge production. However, the slow kinetics of IAD, compared to other sulfur-based autotrophic denitrification (SAD) processes, limits its engineering application. Th...

This study aimed to investigate the effect of nano-magnetite on the CO2 reduction of homoacetogens with different extracellular electron transfer (EET) pathways in the microbial electrosynthesis system (MES). Homoacetogens were cathode-cultured in the MES, which was operated under voltages of 0.5 and 0.8 V. Compared with the MES without magnetite,...

Integrating microalgal cultivation with wastewater treatment is a promising option for sustainable resource recovery and eco-friendly wastewater bioremediation. However, harvesting and culture control are major hurdles hindering its application. This study provided an effective solution to these challenges by selective enrichment of auto-floating m...

Intensive animal farming produces large volume of digested liquid, and overdose application often causes the pollution of surface water and groundwater. Therefore, post-treatment is very necessary for the discharging of surplus digested liquid, but the removal of high concentrations of suspended solids (SS) in the digested liquid is a challenge. In...

Autotrophic denitrification using inorganic compounds as electron donors has gained increasing attention in the field of wastewater treatment due to its numerous advantages, such as no need for exogenous organic carbon, low energy input, and low sludge production. Tetracycline (TC), a refractory contaminant, is often found coexisting with nutrients...

Thermal hydrolysis pretreatment (THP) has been widely applied to promote anaerobic digestion (AD). Humic acids (HAs) are a group of insoluble organics and often present in the conventional AD of sludge, but are reportedly substantially released during THP. Thus, the influences of the released HAs on AD shall be investigated, in particular on methan...

For preparing high performance biochar to be applicated in persulfate-based oxidation treatment of wastewater, the feasibility of deriving Fe-N biochar from pharmaceutical sludge by endogenous Fe and exogenous N doping was investigated. With exogenous urea doping, FexN contained biochar (PZBC800U) was successfully derived from endogenous Fe(OH)3 co...

A shift from the acetoclastic to the hydrogenotrophic pathway in methanogenesis under ammonia inhibition is a common observation in anaerobic digestion. However, there are still considerable knowledge gaps concerning the differential ammonia tolerance of acetoclastic and hydrogenotrophic methanogens (AMs and HMs), their responses to different ammon...

Saline wastewater is a big challenge for the application of anammox processes. Although the feasibility of freshwater anammox bacteria for saline wastewater treatment was revealed, its metabolic acclimation to different saline concentrations is still elusive. Here, one low-strength-fed anammox reactor was operated with the shift of saline concentra...

Microalgae have great potential for biofuel production and wastewater treatment, but the high cost of harvesting hinders their practical application. In this study, economic harvesting of hydrophobic microalgae by electro-flotation without coagulation was assessed. The harvesting performance of this method for selected species of freshwater microal...

The stimulatory effect of biochar addition on dry anaerobic digestion (AD) has been rarely investigated. In this study, the effects of commonly used biochars (bamboo, rice husk, and pecan shell) on dry co-AD were investigated using mesophilic batch digesters fed with pig manure and food waste as substrates. The results show that the specific methan...

Membrane fouling has been the primary challenge limiting the application of electrodialysis (ED) technologies in wastewater treatment, particularly the wastewater containing abundant dissolved organic matter, such as the digested sludge centrate. This study proposed an electro-ion substitution modified electrodialysis (EIS-ED) system that can recov...

Increased pressure is being applied to industrial wastewater treatment facilities to adhere to more stringent regulations for the discharge of treated wastewater and to improve energy efficiency of the process. Nitrogen and phosphorous removal can be challenging to achieve efficiently, and in the case of phosphorous removal, can often necessitate t...

Roxarsone (ROX), an organoarsenic feed additive, can be discharged into aquatic environment and photodegraded into more toxic inorganic arsenics. However, the photodegradation behavior of ROX in aquatic environment is still unclear. To better understand ROX photodegradation behavior, the influencing factors, photodegradation mechanism, and process...

Purpose of Review Microbial interaction determines the performance, stability, and resilience of the microbial communities. Understanding microbial interactions benefits the development of environmental biotechnology. The purpose of this review is to summarize the recent findings of microbial interactions in pollution control ecosystems from aspect...

This study compared the rates and microbial community development in batch bioassays on autotrophic denitrification using elemental sulfur (S0), pyrite (FeS2), thiosulfate (S2O32–), and sulfide (S2–) as electron donor. The performance of two inocula was compared: digested sludge (DS) from a wastewater treatment plant of a dairy industry and anaerob...

Roxarsone (ROX) is an organoarsenic feed additive, and can be discharged into aquatic environment. ROX can photodegrade into more toxic inorganic arsenics, causing arsenic pollution. However, the photodegradation behavior of ROX in aquatic environment is still unclear. To better understand ROX photodegradation behavior, this study investigated the...

This study investigated the performance of anaerobic co-digestion (AcoD) of pig manure and food waste on the reduction of antibiotic resistomes under wet and dry AcoD conditions. High-throughput quantitative PCR technology was utilized for a comprehensive assessment of the performances of the two processes. The results show that dry AcoD with a tot...

Aromatic organoarsenicals are widely used in animal feeding operations and cause arsenic contamination on livestock wastewater and manure, thereby raising the risk of surface water pollution. Biological wastewater treatment processes are often used for livestock wastewater treatment. Organoarsenic removal and biotransformation under aerobic and ana...

In many countries, biodiesel production is obstructed because of a high production cost accounting for raw materials, the large acreage needed for the cultivation of oil-yielding vegetable crops, and competition between food and feed. Therefore, biodiesel production requires new approaches for which microbial oils offer a potential solution. Among...

Volumetric oxygen transfer coefficient (KLa) is an important parameter affecting oxygen transfer and nitrogen conversion during biological wastewater management. However, how the generation of nitrous oxide (N2O) responds to the variation of KLa levels is unclear. In this study, N2O generation via the main pathway, which was confirmed to be nitrita...

Layered double hydroxide (LDH) was a kind of layer materials with multi-metal elements and good catalytic performance, but the metals can be dissolved during catalysis. Graphene oxide (GO) was a two-dimensional structure with abundant anionic groups with the potential of immobilizing metals. However, LDH combined with GO (LDH/GO) was few reported i...

This study aimed at exploring filamentous microalgae (Tribonema sp.) as an advantageous co-substrate for anaerobic digestion (AD) of pig manure. Its impacts on the AD performance were assessed in terms of methane yield, energy conversion efficiency, digestion kinetics, and digestate dewaterability. The microalgae substantially improved methane yiel...

Roxarsone, an extensively used organoarsenical feed additive, is often pooled in livestock wastewater. Sulfate exists ubiquitously in livestock wastewater and is capable for arsenic remediation. However, little is known about impacts of sulfate on roxarsone biotransformation during anaerobic digestion of livestock wastewater. In this study, the bio...

Nitrogen removal is often limited in municipal wastewater treatment due to the insufficiency of carbon source, and using food wastes fermentation liquid as carbon source could cut down the cost of operating and recycle food wastes. Food wastes fermentation liquid production and application as external carbon source were explored in the laboratory a...

Ireland is under a great pressure to fulfill its commitment to renewable energy generation and greenhouse gas (GHG) emissions mitigation. Food waste (FW) and pig manure (PM) co-digestion may provide a promising solution. A life cycle assessment was performed in this study to compare the environmental impacts of the FW and PM co-digestion scenario w...

This study proposed a novel electrodialysis (ED) system, named anode-ED, which can utilise the anode of ED in situ to electrochemically remove the antibiotics during nutrient (N and P) recovery from animal manure digestate. The oxidation of targeted antibiotics (sulfadiazine, SD; and tetracycline, TC) by the anode of ED was first assessed in a sing...

Food waste fermentation products could be one of cost-effective organic products to replace marketable carbon source for denitrification, whereas the effects of simple separation on food waste fermentation products and its denitrification performance are limited. In this study, the effect of gauze separation on production of food waste fermentation...

In this study, the environmental impacts of pig manure direct land application and anaerobic digestion (mono- and co-digestion) for biomethane production followed by digestate land application were evaluated by life cycle assessment, with a focus on the dynamic land application of digestate in terms of the nutrient profiles, soil nutrient status an...

Dry anaerobic digestion (AD) has advantages over wet AD in treating high-solid organic wastes like livestock and food wastes, but an elevated total solids (TS) content would affect the AD performances. In this study, methane production of digesters co-digesting pig manure (PM) and food waste (FW) at different TS contents (R1, TS 5%; R2, TS 10%; R3,...

Harmful algal blooms (HABs) have several negative impacts on aquatic ecosystem, and even harm to humans. Utilization of allelochemicals to inhibit microalgal overgrowth is an environment-friendly approach for controlling HABs. This paper demonstrated the development of allelochemicals with algicidal effects, including the development history of all...

Reliable and accurate oxygen-input control, which is critical to maintaining efficient nitrogen removal performance for partial nitritation-anammox (PN-A) process, remains one of the main operational difficulties. In this study, a novel, yet simple system (a simple process for autotrophic nitrogen-removal, SPAN) with precise oxygen-input control wa...

Bipolar membrane electrodialysis (BMED) is promising in nutrient recovery from wastewater containing nitrogen (N) and phosphorus (P), while studies on its product impurity and energy efficiency are insufficient. In this study, we systematically assessed the application of BMED into nutrient recovery from animal manure, with three membrane configura...

Iron sulphides, mainly in the form of mackinawite (FeS), pyrrhotite (Fe1-xS, x = 0–0.125) and pyrite (FeS2), are the most abundant sulphide minerals and can be oxidized under anoxic and circumneutral pH conditions by chemoautotrophic denitrifying bacteria to reduce nitrate to N2. Iron sulphides mediated autotrophic denitrification (ISAD) represents...

Animal manures and food wastes are significant reservoirs of antimicrobial resistant bacteria, among which carbapenemase-producing Enterobacterales (CPE) are resistant to almost all antibiotics and have been detected in these wastes. This study investigated the inactivation of three different CPE strains (KPC-3, OXA-48 and NDM-1 carbapenemase-produ...

The extensive use of roxarsone (ROX) in livestock and poultry husbandry causes the production of arylarsenic-contaminated manure/wastewater. Anaerobic digestion is a conventional technique for livestock manure/wastewater treatment. However, the factors affecting arsenic volatilization are poorly understood in arylarsenic-loaded anaerobic reactors....

Partial nitritation-anammox (PN-A) process, which significantly reduces energy and chemical input compared to the conventional biological nitrogen removal process, is a game-changing nitrogen-removal alternative. PN-A treating municipal wastewater (mainstream PN-A) may shed light on achieving a more sustainable energy-neutral municipal wastewater t...

Biosafety of digestate remains one of the major concerns for anaerobic digestion, which affects the downstream management and may determine the success of anaerobic digestion. Inactivation of pathogens during anaerobic digestion has been reported by various studies, but most of them focus on single specific pathogen and/or operation condition, with...

The disposal of food waste is a challenge for waste management while denitrification is often limited by the shortage of carbon source in wastewater treatment. Food waste has the potential to be used as carbon source for advanced nitrogen removal of secondary effluent. In this study, fermentation liquid production from food waste and the denitrific...

Nutrient (nitrogen and phosphorus) recovery from animal manure using membrane technologies has been well studied, but the migration and accumulation of antibiotics in membrane processes are ignored. This study examined the behaviours of sulfadiazine (SD) and tetracycline (TC) in an electrodialysis reversal (EDR) process designed for nutrient recove...

Roxarsone and sulfadiazine are typical feed additives and often occur in manure and livestock wastewater. Anaerobic digestion is a common technique for the treatment of manure and livestock wastewater. However, the influence of roxarsone and sulfadiazine on anaerobic digestion and their degradation are still unclear. In this study, the effect of ro...

This study investigated nutrient removal kinetics and main influencing factors of natural pyrrhotite autotrophic denitrification (PAD), and nutrient removal performance and the microbial community in the PAD biofilter (PADB). Results demonstrated that both NO3⁻ and PO4³⁻ in wastewater were nearly completely removed, and biological N removal and che...

Background With the increasing global population and increasing demand for food, the generation of food waste and animal manure increases. Anaerobic digestion is one of the best available technologies for food waste and pig manure management by producing methane-rich biogas. Dry co-digestion of food waste and pig manure can significantly reduce the...

Extremely high volatile fatty acids (VFAs) and ammonia concentrations can accumulate during dry co-digestion of organic wastes, which may inactivate pathogenic microorganisms. In this study, inactivation of Salmonella during dry co-digestion of pig manure (PM) and food waste (FW), which are both reservoirs of zoonotic pathogens, was examined. The e...

Membrane technologies are challenged by severe membrane fouling when treating animal manure digestate due to high turbidity and high concentrations of organic and inorganic matter. In this study, a bench-scale electrodialysis reversal (EDR) was carried out to assess its feasibility for nutrient recovery from pig manure digestate. Pretreatment consi...

Conductive materials facilitate direct interspecies electron transfer between acidogens and methanogens during methane (CH4) production. Soluble microbial products (SMP) and extracellular polymeric substances (EPS) produced by microorganisms might act as the electron shuttle between microorganisms and conductive materials. In this study, effects of...

Compared with wet digestion, dry digestion of organic wastes reduces reactor volume and requires less energy for heating, but it is easily inhibited by high volatile fatty acid (VFA) or ammonia concentration. The inhibition on methane production kinetics during dry co-digestion of food waste and pig manure is rarely reported. The aim of this study...

In this Research Communication we investigate potential correlations between key bacterial groups and nutrient removal efficiency in an Intermittently Aerated Sequencing Batch Reactor (IASBR) treating synthetic dairy processing wastewater. Reactor aeration rates of 0·6 and 0·4 litre per minute (LPM) were applied to an 8 l laboratory scale system an...

This Research Communication describes the initial operation of a pilot-scale intermittently aerated sequencing batch reactor system, which is located at an Irish dairy processing factory. Laboratory-scale research has facilitated the design specifications and operational parameters necessary for the construction and running of a pilot-scale. Labora...

This Review describes the objectives and methodology of the DairyWater project as it aims to aid the Irish dairy processing industry in achieving sustainability as it expands. With the abolition of European milk quotas in March 2015, the Republic of Ireland saw a surge in milk production. The DairyWater project was established in anticipation of th...

This Research Communication describes an investigation into the viability of an Intermittently Aerated Sequencing Batch Reactor (IASBR) for the treatment of dairy processing wastewater at laboratory-scale. A number of operational parameters have been varied and the effect has been monitored in order to determine optimal conditions for maximising re...

This Research Communication describes the methodology used and the subsequent results obtained for an assessment of the environmental impact associated with the manufacture of dairy products in the Republic of Ireland. As the Irish dairy industry changes and grows, it is necessary to have a benchmark of the environmental performance of the sector i...

This study investigated the performance and microbial community dynamics of a start-up method for the partial nitritation-anammox (PN-A) process: start-up from return sludge in an intermittently aerated sequencing batch reactor (IASBR). The robustness of this PN-A IASBR system in achieving long-term efficient nitrogen removal was also investigated....