Mechanical biological treatment of waste is still one of the most popular methods for mixed municipal waste treatment. The result of mechanical processing of waste is sorting out: the undersized fraction from municipal solid waste (UFMSW) with granulation below 80 mm, rich in biodegradable organic waste (mainly including food waste, paper, wood, etc.). UFMSW is treated in biological processes in order to reduce the negative environmental effect of this waste. Unfortunately, the processing is not neutral to the environment. The correct course of the aerobic biostabilization process depends on the activity of microorganisms, the intensity of aeration, and the oxygen content in the processed waste. The aim of this paper was to analyze the effect of air-flow rate and biochar addition on the oxygen concentration in waste and in emitted gases during the intensive phase of UFMSW biostabilization. The study was performed under laboratory conditions. Six different variants of the process (without biochar addition and using 1.5; 3; 5; 10 and 20% of biochar addition) were applied. Subsequent replicates were conducted using an averaged air-flow rate of 0.1, 0.2, and 0.4 m 3. d -1. kg dm.org -1 . As a result of the conducted experiments, it was found that both the air-flow rate and the addition of biochar have a significant effect on the oxygen concentration in the treatment waste, as well as its content in the outlet air. Using the highest air-flow rate resulted in the oxygen content not decreasing below 14%, both in the free spaces between the waste and in the emitted gases, while the addition of biochar significantly reduced the oxygen concentration. In the case of lower air-flow rate values, the oxygen content decreased even below 5%. It was found that a high addition of biochar (10 and 20% by weight) at the lowest air-flow rate resulted in the occurrence of anaerobic zones in waste in the first days of the intensive process (between days 2 and 6 of the process), as well as absence of oxygen in the outlet air (between days 2 and 4 of the process). Despite this, no methane (biogas) emissions were found in any of the conducted experiments.
The study was primarily aimed at investigating the effect of brassica sprout consumption, namely rutabaga (Brassica napus L. var. napobrassica) sprouts (R) generally recognized as antithyroid agent due to its goitrogenic substance content, on hematological, biochemical, and immunological parameters in rats. Sprouts were tested alone and in a combination with other antithyroid factors, such as iodine deficiency (RDI) and sulfadimethoxine (RS). The expression of the heme oxygenase-1 (HO-1) gene in the thyroid as a stress-inducible protein was determined. The thermographic analysis was also estimated. The intake of rutabaga sprouts by healthy rats did not reveal any significant, harmful effect on the thyroid function. Both body temperature and expression of HO-1 remained unchanged in response to the consumed sprouts. In animals with hypothyroidism, rutabaga sprouts enhanced the negative effect of iodine deficiency or sulfadimethoxine ingestion on the organism by increasing the WBC (RDI), TNF-α (RS), creatinine (RS), and triglyceride (RDI and RS) levels, as well as decreasing PLT (RS) level. Moreover, rutabaga sprout consumption by rats with iodine deficiency and sulfadimethoxine decreased their body temperature. Additionally, the concomitant administration of sprouts and iodine depletion significantly reduced the expression of HO-1 in the thyroid. The results may prove useful in confirming rutabaga sprout consumption to be safe, though the seeds of this vegetable provide a well-known antithyroid agent. Our results have shown that rutabaga sprout consumption may be also a factor that enhances the negative clinical features only when combined with iodine deficiency and sulfadimethoxine ingestion.
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