Publications

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 >115 mg CO∙m -3 after, exceeding the WHO thresholds for a 1-h and 15-min exposures, respectively.

<b><sc>Abstract.</sc></b> <b>Odorous gas emissions from swine production are the unwanted by-product of farmers. Manure additive has a great potential to solve this problem. Manure additives are considered low-cost and user-friendly; they can be implemented without changing the current manure storage practices. The objective of this study was to evaluate the effectiveness of 12 current commercial manure additives on mitigating odor, ammonia (NH₃), hydrogen sulfide (H₂S), greenhouse gas (GHG), and volatile organic compounds (VOCs) from stored swine manure with pilot-scale setup by strictly following the recommended dosages and procedures from the product labels. Each product was tested for 2 months while gas and odor measurements were done weekly. At the end of the trials, manure properties and microbial communities were analyzed to determine whether manure additives impacting microbes in manure. Preliminary analyses indicate that there is no statistically significant reduction of any measured gas or odor emissions that could be associated with the tested products.</b>

Anaerobic digestion is the most popular technic for obtaining biomethane from substrates like cow manure and other organic materials, however, chlortetracycline (CTC) and sulfadiazine (SDZ) which are commonly used in animal husbandry and present in cow manure can adversely affect biomethane yields. In this paper, the results of the influence of an increasing dose of CTC between 10 and 1000 mg×kg−1 and dose of SDZ between 10 and 500 mg×kg−1 on biomethane yield and kinetics for co-fermentation of cow manure and apple pomace experiment was presented. The obtained data during 21 days of lasting batch tests performed under mesophilic conditions allowed the determination of kinetics parameters of biomethane production according to the modified Gompertz model. The biomethane yield for the experiment with CTC differs from 233 to 353 mlCH4, while for the experiment with SDZ from 396 to 455 mlCH4. The kinetics parameters varied in a broad range. The ymax, λ, and Rm were 232–531 ml, 18–66 ml d−1, and –2.9-(–1.7) d for CTC, and 533–653 ml, 20–21 ml d−1, and –4.5-(–0.8) d for SDZ, respectively. With the high antibiotics dose, the biomethane yield decreased due to the inhibitive effect on microorganisms. The experiment showed that antibiotics had an inhibitory effect on biomethane production, at high doses. The biomethane yield had been reduced by 32.3 % at 1000 mg×kg−1 of CTC and by 13.9 % at 500 mg×kg−1 of SDZ. Interestingly, small doses (<100 mg×kg-1) did not affect significantly methane yield and sometimes increased it. Obtained results showed that the co-fermentation of apple pomace and manure performance may be affected by high doses of antibiotics. Depending on the dose and the antibiotic type it affects the biomethane yield, production rate, or lag phase differently.

Hydrogen sulphide (H2S) gas is typically formed in sewage collection systems that are conducive to creation of septic conditions. Collection systems in warm climates that have a flat grade or do not have the flow-through velocities (minimum two feet per second) to prevent the stagnation of fluid, allow the septic conditions to occur. In general, septic conditions occur when bacteria use all of the available oxygen while decomposing organic matter in wastewater for energy. Sewers with low velocities encourage the growth of anaerobic bacteria in a slime layer coating the sewer. These bacteria reduce sulphur compounds such as sulphate (SO4), thereby producing sulphites (SO2). These compounds occur naturally in domestic sewage but also can be concentrated in industrial waste streams. One of the more frustrating problems of H2S development from domestic and industrial wastewaters in collection systems is odours. Odour problems often are resolved by chemical addition. Chlorine compounds such as bleach, sodium hypochlorite, calcium hypochlorite and ferric chloride are examples of chemicals that are effective in controlling H2S in wastewater collection systems. The aim of the study was to determine the possibility of the application of advanced oxidation process with Fenton’s reagent to the reduction of nuisance of H2S generated at putrefaction of municipal sewage. The experiment was performed at the laboratory scale. Carbon compounds transformations were observed, redox potential, H2S concentration in biogas, and rate of purification were determined. Investigations were conducted in five phases, on laboratory-scale experimental anaerobic reactor at the temperature of 20oC. The research phases varied with the type of chemical reagents supplied to the technological system. Depending on the experimental phase different substances were dosed to the analysed sewage. Ions of Fe2+, Fe3+, H2O2, and advanced oxidation systems Fe/H2O2 and Fe/H2O2 were used in the experiment. Experimental system revealed the significance of coagulation, oxidation and advanced oxidation on deodorization of tested wastewater. Technology of reduction of H2S nuisance, generated at putrefaction of municipal sewage, based on advanced oxidation, allowed to obtain effective final results in relation to all analysed parameters.The most effective reduction of odours nuisance was obtained with classic Fenton reaction. An increase of the efficiency correlated with the increase of oxidant H2O2 doses. The dosage of 0.1 g Fe2+/dm3 and 2 g H2O2 caused sewage putrefaction after 11 days. Sewage putrefaction in control sample was observed after 24 hours. Application of advanced oxidation process was more effective method than other methods tested in the experiment. The final results of sewage preparation were far better than results observed at hydrogen peroxide, Fe2+ or Fe3+ ions application alone. Presented method of odours reduction for the sake of the obtained results, easy operation, chemical reagents accessibility and economical reasons can become alternative technology of reduction of nuisance of H2S generated at putrefaction of municipal wastewater.

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.