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The optimisation tests of sodium percarbonate (biocide) with the formula 2Na2CO3·3H2O2, as a green oxidizing agent for biological deactivation of chicken manure, were carried out. The microbiological analysis of fresh manure which consisted of the enumeration of bacteria, fungi and eggs of intestinal parasites showed that the number of bacteria Enterobacteriaceae, i.e. 8.3 log10CFU/g, and the bacteria E. coli, i.e. 6.96 log10CFU/g, exceeded the required level in organic fertilizers. The Response Surface Methodology for three input parameters (biocide concentration, temperature and time) on the value of E. coli bacteria was applied. The obtained values of the coefficient of the multiple correlation R2 and the adjusted coefficient Radj2 were 0.90 and 0.75, respectively, which indicate a good fit of the data obtained with the model and the experimental data. It was concluded that a decrease in the count of the analysed microorganisms followed an increase in the sodium percarbonate concentration, an increase in the temperature and a longer time of contact of the manure sample with the biocide. The content of bioavailable macronutrients (P, N, Ca, Mg, K) in water extracts of fresh chicken manure before and after its biological deactivation was determined with the ICP-OES method. The concentration of phosphorous in fresh manure extract was 310 mg/l and decreased after addition of one of the following agents: 7.5 wt.% of sodium percarbonate to 66.9 mg/l or 3.0 wt.% of traditional hygienizing agent, i.e. calcium hydroxide to 5.7 mg/l.. The results of the concentration of N in chicken manure with sodium percarbonate was also higher than in sample with calcium hydroxide, i.e. 1040.0 mg/l and 860.0 mg/l, respectively. While the addition of 2Na2CO3·3H2O2 decreased the content of Ca, Mg and K in fresh chicken manure.

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Over the past years, the treatment and use of livestock waste has posed a significant problem in environmental engineering. This paper outlines a new approach to application of calcium peroxide (CaO2) as a green oxidizer and microbiocidal agent in the treatment of poultry manure. It also presents the application of pretreated waste in improvement of degraded soils in industrial areas. The CCD (Central Composite Design) and RSM (Response Surface Methodology) were employed for optimizing the process parameters (CaO2 concentration 1.6–8.4 wt %, temperature 5.2–38.8 °C and contact time 7–209 h). The analysis of variance (ANOVA) was used to analyze the experimental results, which indicated good fit of the approximated to the experimental data (R2 = 0.8901, R2adj = 0.8168). The amendment of CaO2 in optimal conditions (8 wt % of CaO2, temperature 22 °C and contact time 108 h) caused a decrease in bacteria Escherichia coli (E. coli) in poultry manure from 8.7 log10 CFU/g to the acceptable level of 3 log10 CFU/g. The application of pretreated livestock waste on degraded soils and the studies on germination and growth of grass seed mixture (Lollum perenne—Naki, Lollum perenne—Grilla, Poa pratensis—Oxford, Festuca rubbra—Relevant, Festuca rubbra—Adio and Festuca trachypylla—Fornito) showed that a dose of 0.08 g of CaO2 per 1 gram of poultry manure induced higher yield of grass plants. The calculated indicators for growth of roots (GFR) and shoots (GFS) in soils treated with poultry manure were 10–20% lower compared to soils with amended CaO2. The evidence from this study suggests that CaO2 could be used as an environmentally friendly oxidizer and microbiocidal agent for livestock waste.

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The main purpose of this paper was to outline a novel approach for the use of industrial by-products generated in coal mines and coal-fired power plants as the components for artificial soils. Several coal combustion by-products, coal mine waste and organic waste materials were tested at laboratory scale for use in the reclamation of areas degraded by coal mining activity. The role of artificial soils was the land rehabilitation of the high acidic waste heap. The results revealed that the amounts of organic matter (14.87–25.01%) and nutrients in the soil substitutes were sufficient to support plant growth, i.e., N (0.37–0.51%), P (0.23–0.47%), K (1.78–3.17%), Ca (4.93–8.39%) and Mg (1.16–1.71%). A phytotoxicity test using white mustard (Sinapis alba) seeds under laboratory conditions showed good germination results (56–66%) for three soil substitutes that did not contain fly ash from biomass combustion, compared to the reference soil (84%). The relationships established for the aqueous leachate parameters of soil substitutes vs. the Sinapis alba germination revealed negative correlations with electrical conductivity (r = −0.88), SO42− (r = −0.91) and Cl− (r = −0.70) ions; the two latter ones were responsible for the salinity which hampered the germination process of the soil substitutes. Moreover, quite similar correlations were obtained between the germination of Sinapis alba and the trace elements of the soil substitutes: Fe (r = −0.69), Cd (r = −0.72), Cu (r = −0.80), Pb (r = −0.78) and Zn (r = −0.74). However, negative and significant correlations in aqueous leachates were shown only with Ni concentration (r = −0.73). The relevance of these results for the effect of salinity on germination and the early growth of S. alba was discussed in detail and was confirmed with the Principal Component Analysis (PCA). The study proved that the physicochemical characteristic of recycled wastes exhibited their potential usefulness for the reclamation of affected areas such as mine waste heaps.

The significant problem is the treatment of landfill leachate characterized by high chemical oxygen demand (COD) and total organic carbon (TOC) and presence of biodegradation inhibitors such as heavy metals and oily substances. For the case of landfill leachate (pH 7.9, color 1550 mg Pt/L, COD 1880 mg O2/L, TOC 620 mg/L, total nitrogen (TN) 220 mg/L, total phosphorus (TP) 6 mg/L and heavy metals), the effect of elevated pressure and temperature on the decrease COD value by potassium ferrate(VI) (K2FeO4) was investigated. Taguchi method (TM) was employed for optimizing the treatment process parameters (repetition, pH, K2FeO4 concentration, time, temperature, and pressure). Maximizing the criterion function of signal-to-noise (S/N), the optimal parameters were determined: pH 3.5, K2FeO4 2.0 g/L, time 45 min, temperature 30 °C, and pressure of 1 MPa. At optimal conditions, a decrease of color, COD, TOC, and TP was above 91%. Additionally, the decrease of TN was 48.2%. Comparatively, at atmospheric pressure (0.1013 MPa) and at 19 °C, the decrease of color, COD, TOC, TP, and TN was 99.9%, 83.0%, 79.0%, 19.1%, and 100%, respectively. Addition of potassium ferrate(VI) may improve organic compound removal and decreases energy consumption in subcritical water oxidation. Graphical abstract