Lipolytic activity was assayed in samples of Antarctic krill frozen in different conditions and in its liquid digesta with synthetic (tributylglycerol, esters of 2-naphtol and fatty acids C3, C9 , C14 and C18 ) and natural (olive oil) substrates. It was testified that the lipolytic activity is several-fold higher in the crustaceans with high food intake than in those with an empty digestive tract. Krill lipases show higher activity against esters of unsaturated fatty acids that against analogous derivatives of saturated ones and 10-fold higher affinity tributylglycerol (Km = 1.12 mM). Their maximal activity is at pH 6.4 and 37°C. E. superba lipases preserve total activity up to 35°C for 45 minutes, and are completely inactivated at 55°C for 5 minutes. Prevailing part of lipolytic activity is present in krill cephalothorax, however, extracts from krill abdomen also display a marked activity. Krill lipases are probably resistant to an attack of crustacean's proteinases.

Twelve mineral elements and total ash were examined in regard to the possible use as the estimators of digestibility of natural food in Antarctic seals. Four of them: phosphorus, calcium, copper and zinc have proved to give most reliable results. The estimated total dry mass and organic matter digestibilities of fish food in Weddell seals (Leptonychotes weddelli (Lesson)) averaged 82 and 91%, while the corresponding values for krill eaten by crabeaters (Lobodon carcinophagus (Hombron and Jaequinot)) and leopard seals (Hydrourga leptonyx (Blainville)) reached approximately 87 and 91%, respectively.

Improving the effects of hydrolysis on waste activated sludge (WAS) prior to anaerobic digestion is of primary importance. Several technologies have been developed and partially implemented in practice. In this paper, perhaps the simplest of these methods, alkaline solubilization, has been investigated and the results of hydrolysis are presented. An increase to only pH 8 can distinctively increase the soluble chemical oxygen demand (SCOD), and produce an anaerobic condition effect favorable to volatile fatty acids (VFA) production. Further increases of pH, up to pH 10, leads to further improvements in hydrolysis effects. It is suggested that an increase to pH 9 is sufficient and feasible for technical operations, given the use of moderate anti-corrosive construction material. This recommendation is also made having taken in consideration the option of using hydrodynamic disintegration after the initial WAS hydrolysis process. This paper presents the effects of following alkaline solubilization with hydrodynamic disintegration on SCOD

Anaerobic digestion residue represents a nutrient rich resource which, if applied back on land, can reduce the use of mineral fertilizers and improve soil fertility. However, dewatering and further thermal processing of digestate may be recommended in certain situations. Limited applicability of digestate as fertilizer may appear, especially in winter, during the vegetation period or in areas where advanced eutrophication of arable land and water bodies is developing. The use of digestate may be also governed by different laws depending on whether it is treated as fertilizer, sewage sludge or waste. The aim of this paper is to present the effects of thermal treatment of solid fraction of digestate by drying followed by pyrolysis and gasification. Pyrolysis was carried out at the temperature of about 500°C. During this process the composition of flammable gases was checked and their calorific value was assessed. Then, a comparative analysis of energy parameters of the digestate and the carbonizate was performed. Gasification of digestate was carried out at the temperature of about 850°C with use of CO2 as the gasifi cation agent. Gasification produced gas with higher calorific value than pyrolysis, but carbonizate from pyrolysis had good properties to be used as a solid fuel

Primary or secondary sewage sludge in medium and large WWTP are most often processed by anaerobic digestion, as a method of conditioning, sludge quantity minimization and biogas production. With the aim to achieve the best results of sludge processing several modifications of technologies were suggested, investigated and introduced in the full technical scale. Various sludge pretreatment technologies before anaerobic treatment have been widely investigated and partially introduced. Obviously, there are always some limitations and some negative side effects. Selected aspects have been presented and discussed. The problem of nitrogen has been highlighted on the basis of the carried out investigations. The single and two step - mesophilic and thermophilic - anaerobic waste activated sludge digestion processes, preceded by preliminary hydrolysis were investigated. The aim of lab-scale experiments was pre-treatment of the sludge by means of low intensive alkaline and hydrodynamic disintegration. Depending on the pretreatment technologies and the digestion temperature large ammonia concentrations, up to 1800 mg NH4/dm3 have been measured. Return of the sludge liquor to the main sewage treatment line means additional nitrogen removal costs. Possible solutions are discussed.

The aim of the conducted research was to determine the possibilities of using the biomass of macroalgae obtained from Puck Bay during May-September season in biogas production process. Model respirometry chambers were used to determine the amount of produced biogas and examine its quality composition. Depending on the month in which the algal biomass was obtained, the experiments were divided into five stages. In each stage, the effectiveness of the biogas production process was tested for the applied loads in model fermentation chambers in the range from 1.0 kg DOM/m3 · d to 3.0 kg DOM/m3 · d. During the experiments it was found that the efficiency of biogas production varied from 205 dm3/kg DOM to 407 dm3/kg DOM depending on the month of the vegetation season and the applied organic matter load in the chamber. Methane content was very high and ranged from 63% to 74%.

The aim of this paper is to show the basic principles of the anaerobic digestion process. All the stages of degradation, such as hydrolysis, acidogenesis, acetogenesis and methanogenesis are characterized. Biodegradable organic matter consists of three main types of substances: carbohydrates, proteins and lipids; the metabolic pathways of their decomposition are described. The last part of the paper presents the co-digestion process, its benefits and technological parameters required to make that process attractive from an economical and environmental point of view.

This paper presents calculations of the economic indicators of the researched elements of the cultivation technology of corn for grain and vegetable crops in Ukraine, which indicate that the cultivation of these crops is cost-effective in all variants of the experiment. The research has established that the increase in the economic efficiency of the production of these crops when applying different rates of fertilizers is achieved due to a more significant positive effect of the increase in productivity compared to additional costs associated with the use of these farming practices, while additional costs caused by the use of fertilizers are paid off many times over. It has been proven that the use of mineral fertilizers and their combination with high rates of bio-organic fertilizer (digestate) when growing agricultural crops helps to increase productivity. There have been further developed theoretical and practical provisions regarding the ecological problem of livestock waste disposal, in particular those of pig farms, and agricultural farms, i.e. the provision of organic fertilizers to ensure the yield increase as well as improvement in the quality of agricultural and vegetable crops, so as to make it possible to obtain high-quality products of plant and vegetable production during livestock waste disposal. The proposed approach to the economic assessment of technologies for growing corn for grain and red beet depending on the fertilization system makes it possible to increase the level of productivity of agricultural and vegetable crops with the effective use of bio-organic fertilizers in the modern conditions of sharp increases in the costs of mineral fertilizers.

Anaerobic digested sludge supernatant is rich in phosphates and ammonia nitrogen. Phosphates can be almost completely removed in the process of struvite precipitation. Simultaneously, if only magnesium is supplied, usually only a minor part of ammonia equivalent to phosphates will be removed. Increase in pH to about 8.5 or above leads to the presence of free ammonia which affects the struvite crystals form. The possibility of additional ammonia removal with an external or internal source of phosphates was also accounted for. The final product (precipitate) could be considered as a "biofertilizer" or "biosoil" in connection to the technology applied.

Current efforts are taken to increase resource efficiency, close material loops, and improve sustainable waste and by-products management. Thus, networking agro-food by-products andc onverting them into valuable products completely exhausting the potential of the raw material becomes significant. Model lignocellulosic and starch based biomass were subjected to pre-treatment with the application of acidic compounds, i.e. sulphuric (SA) and acetic (AA) acids. The response, i.e. total sugar content and derivatives content is investigated depending on variables changed during hydrolysis: concentration of acid, process duration, temperature and the size of the biomass particles. After saccharification, the hydrolysates were analysed via HPLC. Total reducing sugars concentration was in the range of 0.1 – 15.53 g/LAmong the substances present in the hydrolysates, protein, peptides, hydroxybenzyl acid (HA), 5-HMF, furfural (FF), vanillin (V), vanillic acid (VA), formic acid (FA) and levulinic acid (LA) were found in the range of 0.44 – 9.05 g/L and determined as total derivatives concentration. The aim of the study was to evaluate the measurable effects of the research and deliver information about the statistically important parameters for the process course and relations between the variables.

The paper describes practical results of four-year laboratory studies completed to estimate technically feasible conditions of upgrading an existing sludge disposal system. A minimization of sludge mass and volume together with an energy recovery improvement were main goals of these activities. The way from lab studies and simulations to full scale investments has been shown with a special emphasis on application of respirometric procedure being applied by authors. Proposed was authors’ procedure for an estimation of a digestion time prediction for sludge of specific composition. Investigations completed at existing wastewater treatment plant resulted in practical implementation to be used during the design of upgrading and extension of the digestion and energy recovery system at the plant. It was proved that proposed changes provide close to optimum conditions for process performance and the application of proposed calculation procedures was adopted by design team

This paper presents the results of fractionation of particulate and soluble organic matter in a mixture of maize silage and cattle manure (49:51% volatile solids) that was used as a feedstock for anaerobic digestion. The extended Weender’s analysis was adapted to measure raw protein, raw lipids, fraction of carbohydrates (including starch, cellulose, hemicelluloses) and lignin. The content of individual fractions in composite, Xc (as kg COD kg-1 COD) was: 0.111 proteins, 0.048 lipids, 0.500 carbohydrates and 0.341 inerts. The biodegradability of Xc was 68%. Based on material balance, the carbon concentration in Xc was 0.0326 kmol C kg-1 COD, whereas nitrogen concentration 0.0018 kmol N kg-1 COD. The estimated pH of the feedstock based on acid-base equilibrium corresponded to the actual value (pH 7.14).

The aim of this study was to implement ADM1xp model to simulate behavior of anaerobic co-digestion of maize silage and cattle manure. The accuracy of ADM1xp has been assessed against experimental data of anaerobic digestion, performed at OLR = 2.1 gVS dm-3·d-1 and HRT = 45d. Due to the high number of parameters in ADM1xp, it was necessary to develop a customized procedure limiting the range of parameters to be estimated. The best fitting of experimental to simulated data was obtained after verification of 9 among 105 stoichiometric and kinetic parameters. The values of objective function (Jc) ranged between 0.003 (for valerate) and 211 (for biogas production).

The aim of the study was to develop an effective treatment of post-digestion liquors highly-loaded with biogenic and organic substances. The scope of the research project encompassed: mesophilic anaerobic digestion of waste activated sludge (WAS) as well as the treatment of post-digestion liquors, coming from the most appropriate HRT value of 25 days, in the process of ammonium magnesium phosphate (struvite) precipitation targeted at ammonia nitrogen binding and a subsequent reverse osmosis (RO) process. It was established that the method combining chemical precipitation and high-pressure filtration ensures a high degree of contaminants removal allowing for a direct release of treated liquors into the natural reservoir. However, in order to decrease the residual NH4+ concentration (6.1 mg NH4+/dm3) in the purified post-digestion liquors below the level allowing for a direct release to the natural reservoir, it turned out to be necessary to apply increased molar ratio of magnesium and phosphates (Mg:NH4+: PO43-= 1.5:1:1.5).

The substrates to biogas production in anaerobic digestion, except plant materials, can also be animal feces and manure. It should be highlighted that Poland is one of leaders in the European Union in animal breeding. However, there is no precise data in the literature on the potential of biogas production from animal feces in this country. The aim of the paper was to analyze the biogas production potential from manure in Poland. The aim of work included anaerobic digestion research following materials: cow manure, pig manure, poultry manure and sheep manure. In the next step, based on the obtained results of the biogas yield, energy potential calculations were made. The methane yield for the investigated feedstock materials in the batch culture technology was performed following the internal procedures developed based on the adapted standards, i.e. DIN 38 414-S8 and VDI 4630. Animal wastes were obtained from the Agricultural Experimental Stations of Poznan University of Life Sciences (Poznan, Poland). On a base of achieved results it was concluded that tested substrates have a high energy potential (approx. 28.52 GWh of electricity). The largest potential for electricity production was found in chicken manure (about 13.86 GWh) and cow manure (about 12.35 GWh). It was also shown which regions of Poland have the best chance for development of agriculture biogas plants (Wielkopolskie and Mazowieckie voivodships) and where the potential is the least (Lubuskie and Opolskie voivodeships).

The investigations were carried out in order to assess the effect of thermophilic fermentation on

changes in concentration of seven congeners with codes: 28, 52, 101, 118, 138, 153 and 180 in sewage sludge.

The total concentration of PCBs was the highest before the process of thermophilic fermentation. On the tenth

day of the process of fermentation it was found that the total concentration of LCB doubled the previous level,

whereas in higher chlorinated PCBs this value decreased twice. After the process of thermophilic digestion,

all the determined congeners of PCBs were still present. However, their total concentration was reduced by

84% on the fourteenth day of the process. Low concentration of heavy metal ions in the liquid phase of sewage

sludge was observed. The metal ions precipitated and remained bound throughout the stabilization process.

Metal speciation analysis was performed, and revealed some changes in the chemical forms of the metals during the stabilization process of sludge. The highest increase of zinc, copper, nickel, cadmium, and chromium

concentration was observed in the organic-sulfide fraction, whereas the highest increase of lead was found in

the residual fraction. Thermophilic methane fermentation did not cause the accumulation of heavy metals in the

mobile fractions of sludge.

The geochemistry of sedimentary rocks is increasingly being used in palaeoenvironmental studies, in the identification of marine versus continental stratigraphy and in chemostratigraphic correlation. The selection of an appropriate research methodology, particularly in terms of sample digestion, can have a significant impact on the accuracy of the results obtained. Depending on the type of rock being studied and the aim of the analysis, a suitable mixture of acids should be used. The most commonly used sample digestion methods are based on a mixture of four acids (multi-acid), aqua regia and inverse aqua regia. As opposed to multi-acid whole-rock digestion, the use of aqua regia and inverse aqua regia result in only the partial digestion of sedimentary rocks. Geochemical analyses using these two different methods were carried out on Carboniferous sedimentary rocks from the Lublin Coal Basin from Poland.The elemental concentrations obtained showed essentially different results for some of the elements. A comparison of the elemental concentrations allowed the distinction of three groups of elements:

 - those that showed small differences between the results from the preparation methods (Co, Mn, Bi, Cu, Zn and Fe),

- those where the elemental concentrations were 20–50% lower using aqua regia digestion (i.e. Ni, P, Pb, Mg, Cd, Th, Mo, Sr),

 - elemental concentrations that were significantly lower (by up to 80%) following aqua regia digestion (U, Cr, Ba, Na, V, Al, Rb, K, Zr).

Anaerobic digestion (AD) converts organic matter and biomass waste into biogas, making it an environmentally friendly technology to improve energy resources for a wide range of applications. Jerusalem artichoke straw (JAS) has an enriched content of cellulose and exhibits a high potential for methane production. AD-based production of methane can eff ectively utilize waste JAS. This study investigated the AD performance of JAS to explore the enhancement of methane yields by employing a Box-Behnken experimental design (BBD) of response surface methodology (RSM). The overall goal was to identify the optimal levels of pretreatment factors, including HCl concentration, pretreatment time, and pretreatment temperature, for producing optimal biomethane yields from JAS. The highest value of methane production achieved was 256.33 mL g-1VS by using an optimal concentration of HCl as 0.25 M, a pretreatment time of 10 h, and a pretreatment temperature of 25°C. These results inform the future application of JAS in enhanced methane production.

Most often sewage treatment and sludge disposal are handled as two separate technological parts of treatment plants. Attempts are made to change the practice. Keeping the standards of treated sewage is the primary objective, and sewage sludge is a by-product which has to he get rid of. The environmental consequences of various procedures of sludge disposal are rarely considered. On the other hand, incorporation of sludge handling procedures in the processes of sewage treatment can result in cost savings and be environmentally friendly. In the presented paper, suggestions arc given on possibilities of closer integration of sewage and sludge treatment, based on experiments. Research aimed at sewage sludge quantity minimization and quality upgrading, recovery of phosphorous and efficient nitrogen removal. Appearing occasionally scum floating over biological sewage treatment units was shown to be considered as an integrated part or sewage treatment and sludge handling at EBNRP's.

The potential of organic wastes in Ukraine for biogas production and the prospects of using the family-type biogas plants for this purpose are shown. In the biogas laboratory of the Ukrainian National Forestry University the efficiency of the anaerobic mesophilic digestion of chicken manure of Poltava poultry farm, Kamianets-Podilsky poultry farm and sewage sludge from Lviv wastewater treatment plant (WWTP) was investigated. Different integral indicators of the biogas production and significantly different dynamics of its formation over time were obtained for three investigated substrates. The value of average specific biogas production from the sewage sludge of Lviv WWTP is 0.494 dm3∙(day∙kg FM)–1, which is 5.1 times more comparing the chicken manure of Kamianets-Podilsky poultry farm and 8.0 times more than for the chicken manure of Poltava poultry farm. Strong negative effect of antibiotic treatment of chickens on methane contentin the obtained biogas was established experimentally.

The paper highlights calculations of bioenergy indicators when growing corn for grain and vegetable crops in Ukraine. The research results indicate the economic benefit of growing these crops for all the variants studied. Our research established that an increase in the bioenergy efficiency of the production of these crops is achieved due to the use of different rates of fertilizer application. The increase in productivity that was obtained as a result of the implementation of farming practices exceeds additional costs associated with the use of fertilizers. This confirms the economic benefit of producing these types of crops due to the enhanced bioenergy efficiency achieved through the optimal application of fertilizer.
The conducted research confirms the high energy efficiency of the bio-organic fertilizer (digestate) and the energy-saving technology of growing crops which were studied. High values of the coefficients of energy efficiency were also observed in the variants with the simultaneous application of mineral fertilizers (N90P90K90) and digestate-based bio-organic fertilizer “Efluent” (55.0 t/ha) on experimental sites of corn grown for grain (3.05–3.07), carrot (1.41–1.45) and red beet (1.97–2.00), but the cost of these variants also appeared to be the highest. Scientific research has used new methods and technologies for the effective processing of livestock waste in order to obtain organic fertilizer, which can be used to improve soil fertility and increase crop yields on the one hand, and biogas production as an energy-efficient process that has significant potential for producing ecologically clean and renewable energy on the other. The proposed approach to achieving energy efficiency helps to increase crop yield without increasing fertilization costs.

This article analyzes the perspective of implementing target indicators in the green transition of the agro-industrial complex of Ukraine. It is established that soil degradation has acquired a global dimension, and it has become a serious problem of a socio-economic nature due to the military actions in Ukraine. Analysis of the state of agricultural land was performed based on the following indicators: humus content in the soil, volume of application of organic and mineral fertilizers, pesticides, land area under organic production, etc. The purpose of the study is to assess the impact of implementing waste-free biofuel production technologies at the enterprises of the agro-industrial complex to achieve eco-goals of the European Green Deal. The article outlines target guidelines for achieving eco-goals of the European Green Deal. Further steps necessary to overcome current problems in compliance with the norms of the EU legislation on environmental protection at agricultural enterprises for the sale of agricultural products to European markets are proposed. It has been scientifically proven that the agro-industrial complex of Ukraine has an untapped potential for reducing greenhouse gas emissions through ecological modernization and implementing waste-free production technologies. It is suggested to use biogas plants as a promising means of solving the problems of waste disposal, improving the ecological situation, reducing energy dependence, and increasing soil fertility. The effectiveness of applying organic fertilizer, namely digestate, a by-product of methane fermentation, as biofertilizers at agricultural enterprises has been proven. Recommendations are provided regarding soil regeneration measures in Ukraine in the future.

Plastic is one of the main pollutant sources that are difficult to decompose and then carried into the ocean and fragmented into smaller parts (microplastics) due to UV radiation and water currents. Their small size means that microplastics are often ingested by aquatic organisms, such as fish. This research aimed to determine the presence, abundance, and types of microplastics in the digestive tract of four dominant fishes landed at Lengkong Fish Auction Point, Cilacap, Central Java, i.e. threadfin ( Eleutheronema tetradactylum), mackerel ( Rastrelliger sp.), threadfin bream ( Nemipterus japonicus), and hairtail ( Trichiurus lepturus). We found microplastics in the digestive tract of four selected fishes with a frequency of occurrence of 100%. The concentration of microplastics in fish digestive tracts is relatively high, with a value range of 12 ±2.86 to 28.33 ±8.11 particles∙ind.^-1. Microplastics were found in films, fibres, fragments, and granule shape types with various colours: brown, purple, blue, black, green, transparent, and yellow. The polymers found were polystyrene (PS), nylon, acrylonitrile butadiene styrene (ABS), polyurethane (PU), polypropylene (PP), high-density polyethylene (HDPE), and low-density polyethylene (LDPE). The present study provides baseline data for microplastics contamination in commercial fish species landed at Lengkong Fish Auction Point, Cilacap, Central Java, Indonesia. The fact that we discovered PU, the most harmful polymer, piques our attention.