Publications

<b><sc>Abstract.</sc></b> Hydrogen sulfide and ammonia are always a concern in the livestock industries, especially when farmers try to clear their manure storage pits. Agitation of manure can cause dangerously high concentrations of harmful agents such as H₂S and NH₃ to be emitted into the air. Biochar can absorb these gases. We hypothesized that applying biochar on top of manure can create an effective barrier to protect farmers and animals from exposure to NH₃ and H₂S. In this study, one kind of biochar was tested, highly alkaline, and porous (HAP, pH 9.2) biochar made from corn stover. Two scenarios of (6 mm) 0.25” and (12 mm) 0.5” thick layers of biochar treatments were topically applied to the manure and tested on a pilot-scale setup, simulating a deep pit storage. Each setup experienced 3-min of agitation using a transfer pump, and measurements of the concentrations of NH₃ and H₂S were taken in real-time and measured until the concentration stabilized after the sharp increase in concentration due to agitation. The results were compared with the control in the following 3 situations: 1. The maximum (peak) flux 2. Total emission from the start of agitation until the concentration stabilized, and 3. The total emission during the 3 min of agitation. For NH₃, 0.5” HAP biochar treatment significantly (p<0.05) reduced maximum flux by 63.3%, overall total emission by 70%, and total emissions during the 3-min agitation by 85.2%; 0.25” HAP biochar treatment significantly (p<0.05) reduced maximum flux by 75.7%, overall, total emission by 74.5%, and total emissions during the 3-min agitation by 77.8%. For H₂S, 0.5” HAP biochar treatment reduced the max by 42.5% (p=0.125), overall total emission by 17.9% (p=0.290), and significantly reduced the total emission during 3-min agitation by 70.4%; 0.25” HAP treatment reduced max by 60.6% (p=0.058), and significantly reduced overall and 3-min agitation‘s total emission by 64.4% and 66.6%, respectively.

Furfural is a versatile chemical with many applications across different industrial sectors. However, uncontrolled release of furfural, a volatile organic compound (VOC) primarily derived from thermal processing of lignocellulosic biomass, can pose significant environmental and health risks due to its toxic and potentially carcinogenic properties. Thermal treatment of biomass generates biochar, a carbonaceous by-product with the potential for agricultural, environmental, and biorenewable energy applications. This study investigated furfural release from biochar generated from standard biomass blends composed of lignin, cellulose, and hemicellulose. Furfural release from biochar were influenced by feedstock composition and process temperature, with hemicellulose identified as the primary source. Biochars derived from hemicellulose-rich biomass exhibited the highest furfural release potential, particularly at lower process temperatures (200–275 °C), while release decreased significantly with higher temperature processes (350 °C). Biochar derived primarily from cellulose demonstrated moderate furfural release, primarily at 225–275 °C, whereas biochar from lignin-rich blends had minimal release. A new metric, carbon relative molar mass (CRMM), to model furfural release was introduced. It was found that CRMM is a better predictor of furfural release than the process temperature. Biochars derived from higher CRMM (>27 g·mol−1) were more conducive to furfural release.

Kitchen waste from vegan households can be a raw material for home or backyard composting. However, the use of waste without components like eggshells or meat can constitute several problems, including the decrease of the process temperature and the content of Ca, N, K, Mg, Mn, Na, and S. The scientific aim of the study was to investigate possibility of production and applicability of vegan compost (VC) produced from kitchen waste during 12-weeks backyard composting. The VC properties have been compared to the traditional compost (TC), made from plant- and animal-origin waste materials. Analyzes showed that VC and TC have similar properties, reaching a pH close to 7.5, respiratory activity AT4 &lt;2 mgO2‧(g dry mass)-1and dry matter content of ~79%. VC didn’t show any phytotoxic effect on garden cress; it was characterized by the highest seed germination (100%) and it stimulated the growth of plants’ roots. It was characterized by a higher content of phosphates, P and K, and achieved a lower BOD/COD ratio, demonstrating its maturity and low rotting potential. VC also contained less chloride, Ni, and Pb and showed a lower potential for nitrates leaching. The values of contaminants contained in VC samples didn't exceed the limit values for organic fertilizers. Therefore, studies indicated that plant-based kitchen waste can be a valuable substrate to produce compost and proved that vegan households, restaurants, and cafes are not disqualified from implementing a circular economy by using them assecondary material.

Composting processes reduce the weight and volume of biowaste and produce products that can be used in agriculture (e.g., as fertilizer). Despite the benefits of composting, there are also problems such as odors and the emission of pollutants into the atmosphere. This research aimed to investigate the phenomenon of process gas (CO, CO2, NO, O2) evolution within a large-scale municipal composter. The effects of turning frequency and pile location (outdoor vs. indoors) on process gas and temperature spatial and temporal evolution were studied in six piles (37‒81 tons of initial weight) over a six-month period. The biowaste consisted of green waste and municipal sewage sludge. The chemical composition and temperature of process gases within four cross sections with seven sampling locations were analyzed weekly for ~7–8 weeks (a total of 1375 cross sections). The aeration degree, temperature, CO, CO2, and NO concentration and their spatial and temporal distribution were analyzed. Final weight varied from 66% reduction to 7% weight gain. Only 8.2% of locations developed the desired chimney effect (utilizing natural buoyancy to facilitate passive aeration). Only 31.1% of locations reached thermophilic conditions (necessary to inactivate pathogens). Lower O2 levels corresponded with elevated CO2 concentrations. CO production increased in the initial composting phase. Winter piles were characterized by the lowest CO content. The most varied was the NO distribution in all conditions. The O2 concentration was lowest in the central part of the pile, and aeration conditions were good regardless of the technological regime used. Turning once a week was sufficient overall. Based on the results, the most favorable recommended procedure is turning twice a week for the first two weeks, followed by weekly turning for the next two weeks. After that, turning can be stopped unless additional removal of moisture is needed. In this case, weekly turning should continue until the process is completed. The size of the pile should follow the surface-to-volume ratio: &lt;2.5 and &lt;2 for cooler ambient conditions.

The C/N ratio is an extremely important parameter in the composting process and is directly responsible for the growth of microorganisms. A low C/N ratio contributes to higher emissions of greenhouse gases and odorous substances, such as ammonia (NH3), which is formed by nitrogen mineralization. Due to the highly toxic effects of ammonia, it is a particularly unwanted by-product that can disrupt the composting process since it poisons microorganisms and causes environmental issues. The activity of anammox bacteria, so far analyzed only in wastewater treatment processes, is a particularly efficient method of nitrogen removal, having an advantage over the conventional methods used previously. This study shows the presence of anammox bacteria during composting, which allows for an opportunity to improve the process and reduce its impact on atmospheric pollution. Despite the aerobic nature of this process, the composted mass of waste presents conditions conducive to the development of these ammonia-oxidizing bacteria, as well as the other strains of microorganisms cooperating with them. This makes it possible to compost at a low C/N ratio; in addition, there is no need for an additional energy supply through aeration, as the processes carried out by anammox bacteria do not require oxygen. Therefore, more in-depth research is necessary to evaluate the low C/N effect on anammox and Chloroflexi bacteria growth and its effect on nitrogen balance during composting.

This study analyzed the effect of lightweight aggregates made of fly ash from sewage-sludge thermal treatment (FASSTT LWA) on the effectiveness of phosphorus removal from wastewater in vertical constructed wetlands (CWs), depending on FASSTT LWA content in the CW filling and hydraulic loading rate. It was performed over 13 weeks using 15 lysimeters prepared as double-layer systems. An upper layer was made of FASSTT LWA above the gravel layer with different thicknesses of FASSTT LWA (CW 0 cm: only gravel; CW 12 cm, CW 25 cm; CW 50 cm, and CW 100 cm: only FASSTT LWA). Each filling variant was repeated three times. Wastewater with a mean phosphorus concentration of 7.43 mgP/L was fed to the lysimeters once a day. The hydraulic loading rates tested were 3.0, 5.0, and 7.0 mm/d. Both the increased FASSTT LWA content in the CW filling and the decreasing hydraulic loading rate were found to boost the effectiveness of phosphorus removal in the treated wastewater. Constructed wetland filled in 100 % with FASSTT LWA ensured a reduction in phosphorus concentration below 2.0 mg P/L at all hydraulic loading rates tested.

To date, only a few studies focused on the carbon monoxide (CO) production during waste composting; all targeted on CO inside piles. Here, the CO net emissions from compost piles and the assessment of worker’s occupational risk of exposure to CO at large-scale composting plants are shown for the first time. CO net emissions were measured at two plants processing green waste, sewage sludge, or undersize fraction of municipal solid waste. Effects of the location of piles (hermetised hall vs. open yard) and turning (before vs. after) were studied. Higher CO net emission rates were observed from piles located in a closed hall. The average CO flux before turning was 23.25 and 0.60 mg‧m -2 ‧h -1 for hermetised and open piles, respectively, while after– 69.38 and 5.11 mg‧m -2 ‧h -1 . The maximum CO net emissions occurred after the compost was turned (1.7x to 13.7x higher than before turning). The top sections of hermetised piles had greater CO emissions compared to sides. Additionally, 5% of measurement points of hermetised piles switched to ‘CO sinks’. The 1-h concentration in hermetised composting hall can reach max. ~50 mg CO∙m -3 before turning, and &gt;115 mg CO∙m -3 after, exceeding the WHO thresholds for a 1-h and 15-min exposures, respectively.

The C/N ratio is an extremely important parameter in the composting process, which is directly responsible for the growth of microorganisms. A low C/N ratio contributes to higher emissions of greenhouse gases and odorous substances, such as ammonia (NH3), which is formed by nitrogen mineralization. Due to the highly toxic effects of ammonia, it is a particularly unwanted by-product that can disrupt the composting process because it poisons microorganisms and cause environmental issues. The activity of anammox bacteria, so far analyzed only in wastewater treatment processes, is a particularly efficient method of nitrogen removal, having an advantage over the conventional methods used previously. Our study proofs the presence of anammox bacteria during composting, what gives an opportunity to improve the process and reduce its impact on atmospheric pollution. Despite the aerobic nature of this process, the composted mass of waste presents conditions conducive to the development of these ammonia oxidizing bacteria, as well as other strains of microorganisms cooperating with them. This makes it possible to compost at a low C/N ratio; in addition, there is no need for additional energy supply through aeration, as the processes carried out by anammox bacteria do not require oxygen.

Carbon monoxide (CO), an air pollutant and a toxic gas to humans, can be generated during aerobic digestion of organic waste. CO is produced due to thermochemical processes, and also produced or consumed by cohorts of methanogenic, acetogenic, or sulfate-reducing bacteria. The exact mechanisms of biotic and abiotic formation of CO in aerobic digestion (particularly the effects of process temperature) are still not known. This study aimed to determine the temporal variation in CO concentrations during the aerobic digestion as a function of process temperature and activity of microorganisms. All experiments were conducted in controlled temperature reactors using homogeneous materials. The lab-scale tests with sterilized and non-sterilized mix of green waste, dairy cattle manure, sawdust (1:1:1 mass ratio) were carried out for 1 week at 10, 25, 30, 37, 40, 50, 60, 70°C to elucidate the biotic vs. abiotic effect. Gas concentrations of CO, O2, and CO2 inside the reactor were measured every 12 h. The CO concentrations observed for up to 30°C did not exceed 100 ppm v/v. For 50 and 60°C, significantly (p < 0.05) higher CO concentrations, reaching almost 600 ppm v/v, were observed. The regression analyses showed in both cases (sterile and non-sterile) a statistically significant effect (p < 0.05) of temperature on CO concentration, confirming that the increase in temperature causes an increase in CO concentration. The remaining factors (time, O2, and CO2 content) were not statistically significant (p > 0.05). A new polynomial model describing the effect of temperature, O2, and CO2 concentration on CO production during aerobic digestion of organic waste was formulated. It has been found that the proposed model for sterile variant had a better fit (R2 = 0.86) compared with non-sterile (R2 = 0.71). The model predicts CO emissions and could be considered for composting process optimization. The developed model could be further developed and useful for ambient air quality and occupational exposure to CO.

<b>Abstract.</b> The rural communities are affected by gaseous emissions from intensive livestock production. Practical mitigation technologies are needed to minimize emissions from stored manure and improve air quality inside barns. In our previous research, the one-time surficial application of biochar to swine manure significantly reduced emissions of NH₃ and phenol. We observed that the mitigation effect decreased with time during the 30-day trials. In this research, we hypothesized that bi-weekly reapplication of biochar could improve the mitigation effect on a wider range of odorous compounds using larger scale and longer trials. The objective was to evaluate the effectiveness of biochar dose and reapplication on mitigation of targeted gases (NH₃, odorous VOCs, odor, GHGs) from stored swine manure on a pilot-scale setup over 8-weeks. The bi-weekly reapplication of the lower biochar dose (2 kg/m²) showed much higher significant percent reductions of emissions for NH₃(33% without & 53% with reapplication) and skatole (42% without & 80% with reapplication), respectively. In addition, the reapplication resulted in the emergence of statistical significance to the mitigation effect for all other targeted VOCs. Specifically, for indole, the % reduction improved from 38% (p=0.47, without reapplication) to 78% (p=0.018, with reapplication). For phenol, the % reduction improved from 28% (p=0.71, without reapplication) to 89% (p=0.005, with reapplication). For p-cresol, the % reduction improved from 31% (p=0.86, without reapplication) to 74% (p=0.028, with reapplication). For 4-ethyl phenol, the percent emissions reduction improved from 66% (p=0.44, without reapplication) to 87% (p=0.007, with reapplication). The one-time 2 kg/m² and 4 kg/m² treatments showed similar effectiveness in mitigating all targeted gases, and no statistical difference was found between the dosages. The one-time treatments showed significant % reductions of 33% & 42% and 25% & 48% for NH₃ and skatole, respectively. The practical significance is that the higher (one-time) biochar dose may not necessarily result in improved performance over the 8-week manure storage, but the bi-weekly reapplication showed significant improvement in mitigating NH₃ and odorous VOCs. The lower dosages and the frequency of reapplication on the larger-scale should be explored to optimize biochar treatment and bring it closer to on-farm trials

Enzymatic hydrolysis leads to improved functional and biological properties of protein by-products, which can be further used as nutraceuticals and protein ingredients for food applications. the present study evaluated AcE-inhibitory, antioxidant and immunostimulating activities in hydrolysates of egg-yolk protein by-product (YP), generated during industrial process of delipidation of yolk. the protein substrate was hydrolyzed using non-commercial protease from Asian pumpkin (Cucurbita ficifolia). the reaction was conducted in 0.1 M t ris-Hcl buffer (pH 8.0) at temperature of 37°c for 4 hours using different enzyme doses (100-1000 U/mg of substrate). the protein degradation was monitored by the determination of the degree of hydrolysis (DH), release of free amino groups (FAG) and by rP-HPLc. In the obtained hydrolysates we also evaluated biological activities. It was shown that the highest DH of substrate (46.6%) was obtained after 4h of reaction at the highest amount of enzyme. this hydrolysate exhibited antioxidant activity, including ferric ion reducing (FrAP) (56.41 μg Fe 2+ /mg), ferric ion chelating (695.76 μg Fe 2+ /mg) and DPPH free radical scavenging (0.89 μmol trolox eq /mg) as well as AcE-inhibitory (Ic 50 =837.75 μg/mL) activities. the research showed improved biological properties of enzymatically modified YP by-product.