Odor Control Research Articles

Smart instrumental Odour Monitoring Station for the efficient odour emission management and control in wastewater treatment plants

Odour emission assessment in wastewater treatment plants (WWTP) is a key aspect that needs to be improved in the plant management to avoid complaints and guarantee a sustainable environment. The research presents a smart instrumental odour monitoring station (SiOMS) composed of an advanced instrumental odour monitoring system (IOMS) integrated with other measurement units, for the continuous characterization and measurement of the odour emissions, with the aim of managing the potential odour annoyance causes in real time, in order to avoid negative effects. The application and on-site validation procedure of the trained IOMS is discussed. Experimental studies have been conducted at a large-scale WWTP. Fingerprint analysis has been applied to analyze and identify the principal gaseous compounds responsible for the odour annoyance. The artificial neural network has been adopted to elaborate and dynamically update the odour monitoring classification and quantification models (OMMs) of the IOMS. The results highlight the usefulness of a real-time measurement and control system to provide continuous and different information to the plant operators, thus allowing the identification of the odour sources and the most appropriate mitigation actions to be implemented. The paper provides important information for WWTP operators, as well as for the regulating bodies, authorities, manufacturers and end-users of odour monitoring systems involved in environmental odour impact management.

Development of LEEO® technology for efficient H2S control from saline wastewater sludge: From lab study to pilot trial

Sulfate-laden wastewater presents a challenge in controlling hydrogen sulfide during sludge treatment and disposal. Wastewater in areas such as Hong Kong SAR presents copious amounts of sulfate from seawater toilet flushing, reflecting high sulfate (100–150 mg-S/L) in the sewage sludge. To resolve this critical issue, a new electrochemical pretreatment process, Low Energy Electrical Odor control (LEEO®), was developed to suppress sulfide production in the sludge from lab studies to a pilot demonstration (~7 m3 sludge/day) at a local chemically enhanced primary treatment works. LEEO® simultaneously eliminated sulfide production for up to 5 days while having enhanced dewaterability of 20–30 % without chemical addition. The total energy consumption could be reduced to 0.20 kWh/kg total solids by optimizing the operation input for sludge sulfide control. Furthermore, the LEEO® pilot system demonstrated stability toward sulfide control under different weather (e.g., rainy and sunny) and temperature (23–38 °C) conditions, and confirmed the low comparative developmental toxic impact on the final effluent of the trialed treatment works. The successful upscaling from lab study to pilot demonstration laid the foundation for a full-scale demonstration development of LEEO® as an efficient and long-lasting sulfide control method for saline or sulfate-laden wastewater sludge.

Odor characteristics and health risks during food waste bioconversion by housefly (Musca domestica L.) larvae

Bioconversion by housefly (Musca domestica L.) larvae is a novel technology for reducing and recycling food waste. In this study, odor characteristics and health risks of gaseous pollutants from food waste bioconversion by housefly larvae were investigated and compared with other treatment technologies for the first time. Air samples were collected from different areas in a full-scale food waste bioconversion facility (50 t/d). The chemical compositions of the air samples were quantitatively and qualitatively analyzed, the odor contribution and annoyance were assessed with the odor activity values and their sum, and the health risks (carcinogenic and non-carcinogenic risks via inhalation and other risks) were evaluated. The total concentrations of volatile compounds were significantly higher in the breeding and biodegradation areas than in the other areas. Ethanol was the dominant odorant in the unloading, pretreatment, substrate storage, and breeding areas, while that was ammonia in the biodegradation and product areas. The sums of odor activity values in the breeding and biodegradation areas were the highest (1171 and 756, respectively) with trimethylamine as the key odorant. Carcinogenic risk in the breeding area was unacceptable with acetaldehyde as the key carcinogen, and possible carcinogenic risks existed in the other areas except for the substrate storage area. Non-carcinogenic risk existed in the order of breeding area > biodegradation area > product area > pretreatment area with acetaldehyde, ethyl acetate, hydrogen sulfide, and ammonia as the dominant contributors. The bioconversion technology showed different odor characteristics and health risks from other treatment technologies. Therefore, odor control and health protection measures should be taken based on the odor and health risk evaluation, especially in the breeding area. Suggestions on gas collection and treatment method selection were proposed. The findings provide a scientific basis for odor control and health protection in food waste bioconversion facilities.

Heterospecific eavesdropping on disturbance cues of a treefrog.

Alarm signals and cues are crucial to animal survival and vary greatly across species. Eavesdropping on heterospecific alarm signals and cues can provide eavesdroppers with information about potential threats. In addition to acoustic alarm signals, evidence has accumulated that chemical alarm cues and disturbance cues can also play a role in alerting conspecifics to potential danger in adult anurans (frogs and toads). However, there is very little known about whether disturbance cues are exploited by heterospecifics. In the present study, we conducted a binary choice experiment and a prey chemical discrimination experiment, respectively, to test the responses of a sympatric anuran species (red webbed treefrogs, Rhacophorus rhodopus) and a sympatric predator species (Chinese green tree vipers, Trimeresurus stejnegeri) to disturbance odors emitted by serrate-legged small treefrogs (Kurixalus odontotarsus). In the binary choice experiment, we found that the presence of disturbance odors did not significantly trigger the avoidance behavior of R. rhodopus. In the prey chemical discrimination experiment, compared with odors from undisturbed K. odontotarsus (control odors) and odorless control, T. stejnegeri showed a significantly higher tongue-flick rate in response to disturbance odors. This result implies that disturbance odor cues of K. odontotarsus can be exploited by eavesdropping predators to detect prey. Our study provides partial evidence for heterospecific eavesdropping on disturbance cues and has an important implication for understanding heterospecific eavesdropping on chemical cues of adult anurans.

Odorants in the organophosphorus pesticide contaminated soils：identification, prioritization, and quantification using GC-HRMS based on target and non-target screening

Odorants from the pesticide site remediation were complex and changeable, and the screening of key odorous substances was the prerequisite for the process of odor control. In the study, a novel odorants identification method based on the targeted and non-targeted approach by gas chromatography-quadrupole/electrostatic field orbitrap high-resolution mass spectrometer (GC Orbitrap/MS) was established to investigate the low-concentration odor pollution in three organophosphorus pesticide sites. The comprehensive odor characterization method was developed and applied in the light of olfactory threshold, flavor characteristics, molecular structure, response value, and detection rate. 98 pollutants were screened out using target analysis, and 149 substances were identified with confidence levels of at least 2 based on non-target analysis. Based on the analysis results, 42 odorants were screened out by the synthetic evaluation method for priority control, including phenols, aldehydes, ketones, esters, organic sulfide, amines, nitriles, amide, acylchlorides, ethers, heterocyclic, halogenated benzene and polycyclic aromatic hydrocarbons. The limit of detection (LOD) of 42 odorants was from 0.010 to 0.100 ng L−1, which was lower than other detection methods. This research provided a new technology for identification of odorants in pesticide sites.

Assessment of limited downstream nitrate dosing for sulphide control in pressure sewers: case study in Germany

Abstract Odour release from sewer systems is an established environmental issue affecting many cities worldwide. A key indicator for the severity of the odour problem in sewer systems is linked to the amount of sulphide produced and released as hydrogen sulphide (H2S) into the urban environment. For this reason, an in-depth understanding of the biochemical processes of sulphurous compounds in sewer systems is an underlying base point for designing and implementing odour control strategies for sewer systems. This contribution focuses on a field study on the monitoring and assessing chemical dosing on a 9.0 km pressure sewer in Ueckermünde, Germany. Online H2S measurements indicated a daily reoccurrence of sulphide spikes between 4:00 and 8:00 am during the monitoring period. During this period, the wastewater slugs exiting the sewer section remained in the dosed section of the pipe the longest, and regeneration of sulphide production began after 3 hours, causing the hydrogen sulphide spikes. The proposed dosing strategy provides a cost-effective and efficient solution for sulphide build-up in long pressure sewers that connect rural areas to centralised wastewater collection and treatment systems.

32661 Clinical evaluation of deodorant efficacy and tolerance for overall body odor control

Sweating and associated odor negatively impact self-confidence and social acceptance as they are linked to poor hygiene. Rapid multiplication of bacteria and sweat breakdown causes malodor. High “sweaters” e.g. with hyperhidrosis, are more susceptible to developing body odor. While deodorants for the axilla are used to contain odor, there is need for products to help eliminate other body part odors as well. A randomized, blinded clinical study in healthy volunteers (F, 18-67y) testing involving 3 body odor control products with completion of 90 volunteers (30 per arm). Clinical design involved 1 randomized underarm designated as the treatment site, receiving 1 of 3 test products with the other underarm remaining untreated. Four expert graders conducted underarm visual and malodor assessments at 8, 12, 24, 48, and 72 hrs after final product application. Efficacy of the product on vaginal/perineal/anal malodor was determined at 8 hours after application. The results of the comparative malodor analysis indicated significant differences between products at all assessment intervals favouring PCR Code A as statistically more effective in controlling malodor at all timepoints. Posttreatment malodor scores with PCR Code A use on their private parts indicated a significant reduction in malodor from baseline, 8 hours postapplication. Subject perception showed highly favourable results for product attributes of feel, texture, no residue, odor reduction, skin tolerance, and dual purpose. In conclusion, the dual-purpose deodorant with its clinically proven performance in terms of feel, odor control and low skin irritation potential is effective in controlling arm pit and vaginal/perineal/anal odor.

Flexible decision-making framework for developing operation protocol for water distribution systems

Past water distribution systems (WDS) management studies derived operation protocols to maximize WDS reliability by using residual chlorine as the sole surrogate parameter for water quality reliability. Albeit the advancement in mechanistic modeling to examine the WDS water quality, emerging water quality parameters of concern are not yet involved in solving WDS management problems. This paper attempts to overcome this limitation by developing a flexible decision-making framework -integrating EPANET-C, a mechanistic modeling tool for WDS water quality, with Analytic Hierarchy Process (AHP), a multi-criteria decision-making method - to rank the possible water quality parameter-based operating alternatives (organic matter and residual chlorine levels at the source points) for WDS. The uncertainty analysis was incorporated into the mechanistic modeling using the Monte Carlo method to realize insufficient knowledge about the complex biological and physicochemical interactions inside WDS. Six cases, each ranking the alternatives diversely, were applied to reflect the expert judgment impressions on the AHP outcomes. The consistency of the proposed decision-making framework was verified by deriving the operation protocol for two test networks by making trade-offs between the multiple and conflicting microbiological, chemical, and organoleptic quality criteria. The disinfection by-products formation control and taste and odor problems control emerged as the most critical water quality criteria determining the WDS performance under the operating alternatives examined. Altogether, the obtained results suggested the practicality of adopting a flexible operation protocol to maintain the water quality benchmarks over various plausible WDS performance scenarios, ranging from worst to best.

Disposal of Garden Waste by Analysing Selected Physico-Chemical and Biological Parameters Using In-Vessel Composting at a Community Level

For composting of garden waste, the selection of reactor is an important factor for efficient degradation. The present study evaluates working performance of rotary drum reactor (RDR) and aerated in-vessel (AIV) for composting of garden waste. 500 kg garden waste was mixed with 50 kg cow-dung slurry and 10 kg compost and fed into both the reactors for 45 days composting period. The reactors vary in their system configuration, shape and orientation, blade design, rate of aeration, odour control, leachate production and energy requirements. Rotary drum was rotated daily six times in clockwise and anti-clockwise direction and AIV was rotated daily for 3-5 minutes using motor. Rise in temperature started within 24 hours of composting and reached 65°C (RDR) and 59°C (AIV) on second day itself and thermophilic phase continued for 5 (RDR) and 7 (AIV) days. Moisture content reduction after composting period was 15.25 and 18.45 %, C/N ratio was 16.14 and 13.33, total volatile solids reduction was 23.74 and 29.78 % and CO2 evolution rate was 6.18 and 4.14 mg/g VS/day in RDR and AIV respectively. Reduction of hemicellulose, cellulose, and lignin was more in AIV as compared to RDR. The percentage reduction of acid insoluble lignin was 36.10 and 29.01 % and the percentage reduction of acid soluble lignin was 48.85 and 43.3% in in AIV and RDR respectively. AIV gave better performance for composting of garden waste due to its blade design and structural configuration. The novelty of the present study lies in its approach to empower communities to select best alternative as per their waste generation, budget available, land and labour requirements and behaviour of citizens towards waste.

Smellscape of a Pompeian neighborhood

AbstractSmelling and other sensations that are often considered solely physiological phenomena are in fact deeply influenced by culture and history, and without understanding the ancient sensory landscape, our knowledge of the past inevitably remains limited. This paper explores the olfactory nuisances in one Pompeian city block (IX,3) and its immediate neighbors. I examine the area's stenches by tracing and mapping the sources of smells, focusing on those that in previous scholarship have been considered to render ancient towns foul smelling. The analysis contests the views of malodorous Roman urban space presented in previous studies and suggests that the smellscape of urban Pompeii was not a constant reek but milder and manageable. However, the analysis also reveals that social hierarchies and power relations played a part in Pompeian odor control, and the olfactory landscape was not the same for all inhabitants.

Kinetic optimization of odor adsorption with acetate fiber cloth prepared from waste cigarette filter

Odor pollution with NH3 as major contributor is a notorious issue that strongly influences our living environment. NH3 removal with acetate fiber cloth (AFC) prepared from waste cigarette filter is an economic feasible approach for simultaneous solid wastes disposal. Herein, waste cigarette filter was used to prepare AFC through hot-pressing approach, which was convinced to have good adsorption efficiency on NH3 due to large specific surface area. Effects of hot-pressing temperature, pressure and pressing time on AFC mechanical property and NH3 adsorption efficiencies were optimized by response surface method. As results, hot-pressing treatment improved the specific surface area of AFC to 9.530 m2/g, and thus enhanced NH3 adsorption efficiency to 68.73 % under hot-pressing temperature of 146 °C, pressure of 12.5 kPa and pressing time of 33 min. While the optimal tensile strength of AFC was obtained as 90.43 N under hot-pressing temperature of 140 °C, pressure of 15.0 kPa and pressing time of 30 min. The work provided an economic feasible approach for waste cigarette filter recycling and odor control.

Effects of compound bacterial agent on gaseous emissions and compost maturity during sewage sludge composting

The study aimed to provide an efficient compound bacterial consortium (CBC) containing three thermotolerant sulfide-oxidizing bacteria (SOB) strains to elucidate the effects of bacterial inoculation on odor emissions and maturity of sewage sludge composting. Compared to the single strain, the CBC exhibited more efficient sulfide oxidation capacities and enhanced enzymatic thermostability with the optimal temperature range of 40–50 °C. After inoculating the CBC agent into the 32 L reactors for 22 d composting, the cumulative H2S, NH3, and NO odor emissions of the inoculated group were reduced by 48.9%, 19.4%, and 57.8%, respectively, compared with the control group. The reduced sulfur was oxidized to sulfate with the action of the SOB to avoid H2S emissions, and the pH decrease process also facilitated the reduction of NH3 and NO emissions. Additionally, the increase of sulfate and germination index (GI) suggested that the CBC agent promoted sulfur conservation and compost maturity. Redundancy analysis indicated the close correlations of O2, temperature, and pH on odor emissions; the partial least squares path modeling demonstrated both direct and indirect (by reducing odor emissions) positive impacts of bacterial inoculation on sulfate production. The results implied an effective strategy of CBC agent inoculating into SS composting to control odor release and accelerate the composting process.

Identification of odour compounds emitted by wooden boards with the presence of indoor ozone

Indoor volatile organic compounds (VOCs) produce odours that reduce perceived air quality. Furnitures and indoor decoration are the main sources of indoor VOCs. Considering the increase in outdoor and indoor ozone concentrations, ozone, as a strong oxidant, can have an impact on indoor odour. Herein, medium-density fibreboard (MDF) and flame retarded plywood (FRP) were selected as experimental materials, and gas chromatography-olfactory-mass spectrometry (GC-O-MS) was performed to identify the odour compounds emitted by materials with and without 100 ppb ozone. MDF1, MDF2 and FRP emitted 6, 8 and 14 different odour compounds, respectively. MDF2 emitted moderate grassy and sour odours. FRP emitted moderate grassy, fruity, rubber and pine incense odours. After 8 h of exposure to ozone at a concentration of 100 ppb, MDF1, MDF2 and FRP emitted different odour compounds, respectively. The characteristic odours of MDF were aggravated. Except for pine incense odour, the intensity of other characteristic odours of FRP was weakened. Through cluster heatmap analysis and principal component analysis, the characteristic odour compounds of MDF and FRP were further clarified. Introducing a SOI model, the results showed that ozone exposure increased the SOI of MDF1 and MDF2 from 3.34 to 4.22 and from 4.11 to 4.44, respectively, and that the odour intensity of FRP decreased from 3.78 to 3.41. It can be determined that ozone may have opposite effects on the odour emitted by different materials. The results clarify the target pollutants for odour control research on wooden board emissions.

Evaluating perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) removal across granular activated carbon (GAC) filter-adsorbers in drinking water treatment plants

Granular activated carbon (GAC) was harvested from six filter-adsorbers that are used for taste and odour control in three drinking water treatment plants in Ontario, Canada, and evaluated for the removal of perfluorooctanic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) using minicolumn tests under different operational conditions. Parallel column tests were conducted using unsterilized GAC and sterilized GAC to distinguish adsorption from potential biodegradation of PFOA and PFOS across the GAC. It was observed that the GAC could achieve approximately 20% to 55% of PFOA and PFOS removal even after a long period of GAC operation (e.g., 6 years). There was no evidence of PFOA and PFOS biodegradation, so the removal in GAC can be attributed solely to adsorption under the conditions tested. However, in one location, there was evidence suggesting both removal and formation of PFOS and PFOA across the GAC, with the formation presumably due to the biotransformation of pre-existing precursors in the source water. Additionally, GAC service time and empty bed contact time (EBCT) were identified to be important factors that could affect the removal of PFOA and PFOS. Based on this information, an empirical model was proposed to predict PFOA and PFOS removal in GAC filter-adsorbers as a function of GAC service time and EBCT. This study provides useful information for utilities that have installed GAC for taste and odour control but may consider per- and polyfluoroalkyl substances (PFAS) removal as an additional voluntary objective or due to more stringent guidelines.

Honey as a Medium of Non-Surgical Periodontal Therapy

Gingivitis is an infection caused by plaque and calculus accumulation. Gingivitis if not treated progress to periodontitis, a more advanced form of gum disease. Periodontal disease was the world's 11th most frequent disease in 2016 according to the World Health Organization. Surgical as well non- surgical periodontal therapies are carried out for periodontal disease treatment. Debridement of supra-gingival and sub-gingival calculus, along with instructions about oral health care methods are the basis of traditional non-surgical periodontal therapy (NTPS). Honey is beneficial to oral health, particularly in the cure of plaque formation, gingiva inflammation, periodontitis and odor control. Honey has antibacterial activity and is effective against both gram-positive as well as gram-negative bacteria. Honey's antibacterial and anti-inflammatory characteristics can promote the granulation tissue formation and enabling damaged cells to be regeneration. Materials And Method: This review followed the guided framework from the approach of Arksey and O'Malley for the scoping review (2005). The methodology was chosen because it has a five-stage framework. Exclusion & inclusion criteria were made and 60 articles were selected. Articles were searched from the PubMed, Google Scholar and other search engines. Results: Based on the data retrieved we concluded that honey can be used as a medium for non-surgical periodontal therapy. Honey have antibacterial and anti-inflammatory properties due high osmolarity, acidic nature and hydrogen peroxide as well non-peroxide components of honey and is used by many researcher for cure of periodontal disease but still there is not very strong evidence that locally given honey affects periodontal tissue healing. Despite this, all of the pockets had a good periodontal repair. Honey's efficacy in the treatment periodontal disease is still not well established and still questionable. To substantiate these findings from the literature, more research will be required.

A study on the antibacterial efficacy of Halohydantoin-containing foams

Heterocyclic N-halamine compounds such as 1-monochloro-5,5-dimethylhydantoin (MCDMH) and 1,3-dichlor-5,5-dimethylhydantoin (DCDMH) show antimicrobial activity and odour control. Both MCDMH and DCDMH stabilise and display oxidative chlorine (Cl+1) and, in aqueous environments, generate hypochlorous acid (HOCl). It is well known that HOCl, produced by neutrophils as part of the respiratory immune response, is used as a defence mechanism against foreign bodies. This study aimed to investigate the antibacterial efficacy of proprietary foaming formulations containing mixtures of MCDMH and DCDMH provided by MedeSol Inc., as a potential delivery mechanism for HOCl. The efficacy of the foams containing active chlorine concentrations of 350 ppm and 1050 ppm was tested against single and multi-species bacterial mixtures of S. aureus, P. aeruginosa, E. coli, E. faecalisand K. pneumoniae. Cellulose filters were contaminated with single/multispecies bacterial suspensions and left to air-dry; the two foam concentrations were applied for 15, 30 and 60 seconds at a time. Samples were taken and the total viable count method was employed to determine antibacterial efficacy of the foams. Following the use of both foam concentrations, no colonies were recovered at any time-points in both single and multi-species experiments. In contrast, the negative controls where the foam application was omitted, resulted in high numbers of bacterial colonies. MCDMH-containing foams have very strong antibacterial potential as a result of active chlorine release. Further studies are needed to determine concentration dependence and use in other applications including hand sanitation.

Odors Emitted from Biological Waste and Wastewater Treatment Plants: A Mini-Review

In recent decades, a new generation of waste treatment plants based on biological treatments (mainly anaerobic digestion and/or composting) has arisen all over the world. These plants have been progressively substituted for incineration facilities and landfills. Although these plants have evident benefits in terms of their environmental impact and higher recovery of material and energy, the release into atmosphere of malodorous compounds and its mitigation is one of the main challenges that these plants face. In this review, the methodology to determine odors, the main causes of having undesirable gaseous emissions, and the characterization of odors are reviewed. Finally, another important topic of odor abatement technologies is treated, especially those related to biological low-impact processes. In conclusion, odor control is the main challenge for a sustainable implementation of modern waste treatment plants.

The Role of Steroidogenic Factor‐1 Neurons in Predator Odor‐induced Muscle Thermogenesis

Obesity is one of the most prevalent diseases quietly plaguing this nation. With predictions of its prevalence nearing almost 50% of the adult US population by the end of this decade, it is paramount to identify underlying mechanisms. Characterized by its imbalance of energy intake and energy expenditure, obesity can be countered by amplifying metabolic rate, including inducing thermogenesis. Primarily research has sought to understand adipose tissue thermogenesis, leaving little attention directed toward the brain mechanisms that regulate skeletal muscle thermogenesis. Published evidence from our research program has established that exposure to predator odor (PO) evokes a robust thermogenic response in the skeletal muscle, suggesting that PO works through an unknown brain mechanism causing the thermogenic response. This metabolic response and the stimulation by predator threat each implicate the dorsomedial subregion of the ventromedial hypothalamus (dmVMH), and more specifically, the steroidogenic factor 1 (SF1) cells within it, as a region for further investigation. We hypothesize that SF1 neurons of dmVMH are a key node for predator odor‐induced muscle thermogenesis. We use designer receptors exclusively activated by designer drugs (DREADD) delivered using a viral vector to SF1‐Cre mice to assess this hypothesis. Utilizing DREADD technology, we stimulated the SF1 cells in the presence of a control odor or PO (ferret odor). Here, we analyze preliminary data looking at the muscle thermogenesis of SF1 Cre mice that have been bilaterally injected with mCherry control vector or an excitatory DREADD vector. Using clozapine‐N‐oxide (CNO) and manipulation of context (i.e., with or without the presence of PO), we have detected increases in thermogenesis with each PO exposure and CNO activation of SF1 neurons. However, these data provide little to no evidence of DREADD‐induced amplification of the PO‐induced thermogenesis. Our preliminary data supports the importance of SF1 neurons and their role in regulating PO‐induced skeletal muscle thermogenesis.

A study on the environmental improvement of Jeju pork industry

This study suggests sustainable environmental improvement plans by analyzing the present situation and transition of Jeju pork industry. In 2018, Jeju pork took up 37% of the whole animal products and 14.5% of the sum agricultural and livestock products showing how firmly the industry is supplying pork to the table. In 2019, 268 pig farms with 551,168 pigs (4.9% of whole domestic population) are located in Jeju area. Dealing with the increasing civil complaints about livestock odor, control systems such as assigning odor control restricts. The nation’s first odor control restricts were assigned in 59 sites in March, 2018, 44 sites in June same year and 115 sites in September, 2020. Assigned odor control restrict farms showed the effort to prevent the spread of odor by installing the following facilities: 65% windowless housing, 56% bio-curtain for those who cannot use windowless housing, 70% mist equipment, combining operation the bio-curtain, mist equipment and the liquid manure circulation system. The Central Government and Jeju Special Self-Governing Province are required to take actions for the effective policy change by assisting financially and legally such as establishing ordinances reflecting advanced waste-water purification and settled levels of water quality of reused water.

Construction of a Novel Closed-Loop Livestock Waste Valorization Paradigm: Bridging Manure and Ammonia Gas via Phosphate-Doped Hydrochar

Sustainable livestock production plays an important role in meeting the growing global demand for animal products. Livestock manure and odor emission are regarded as the major obstacles to the low-carbon livestock farming. In response, we propose a novel loop for the valorization of livestock wastes, via bridging manure and the typical odor NH3 with P-doped hydrochar. P-doped cow manure hydrochar was facilely prepared via hydrothermal carbonization followed by H3PO4 activation. The organic composition and crystallinity of hydrochar as the precursor, depending on hydrothermal severity, significantly impacted the subsequent H3PO4 activation behavior. The activated sample with modified surface exhibited favorable NH3 adsorption capacity in the dynamic adsorption experiment. Density functional theory calculation confirmed that the P-containing group improved the NH3 adsorption efficiency as the active site. X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy analyses demonstrated the oxidation of reduced phosphorus groups during NH3 adsorption in room temperature. Phosphorus species strengthened the immobilization of NH3 on the surface via Brønsted and Lewis-type acid–base interaction. This study provided a new strategy to develop a green NH3 adsorbent from the manure-based hydrochar, supporting the further investigation on the promising solution of odor control and waste valorization in livestock farms.