Badania nad wermikompostowaniem odpadów organicznych
AbstractThe objective of this study was to show that the compost earthworm, Eisenia fetida (Say.), has great potential to he used for vermistabilisation of organic wastes whose disposal is one of the major problems faced by environmental protection. It was found that dense populations of compost earthworms can be used to accelerate the biodecomposition of wastes wich are for them an attractive food: the vital functions and metabolic processes of the worms prove usefiil for accelerating the processes of oxygen composting. fetida did not tolerate breeding media from sewage sludge in which anaerobic fermentation had taken place. However, if the sludge was left in suitable conditions for about 3-4 weeks, it could become re-oxygenated and could partially get rid of the metabolites of anaerobic microorganisms which were toxic for earthworms. Media from sewage sludge containing high levels of heavy metals were not accepted by earthworms, either. Besides, their populations developed poorly in media with a low C : N ratio or those based on material from mushroom growing (contaminated with mushroom protection chemicals). The best growth of the populations was obtained when all kinds of wastes were "diluted" with cellulose. In the tests conducted, cellulose from cardboard boxes was used but similar results could be achieved with bark, hay, straw, wastes from fruit and vegetable processing, pulp mill wastes, etc. The distribution of biomass in the observed populations was as follows: individuals with elitellurn. — mean biomass 0.764 ± 0.447 g (min 0.193 g, max 3.600 g), individuals with tuberculae pubertatis — mean biomass 0.346 ± 0.124 g (min 0.107 g, max 0.815 g). Such a high biomass of some individuals with tuber•ulae pubertatis resulted from the disappearance of the well-marked clitellurn, which probably constitutes one of the mechanisms regulating the population size, e.g. in the conditions of starvation or excessive density. The lowest biomasses of the individuals with clitellum were found in media from sewage sludge in which the levels of heavy metals usually exceeded the admissible values. The highest biomasses of adult E. tetida individuals were observed when they were bred for one year in manure-based medium with the addition of cellulose and fed on boiled potatoes. E. fetida laid an average of 1.7 ± 1.4 cocoons per week (min 0.4, max 8.0). The number of cocoons grew with increasing proportion of cellulose in the medium (in sewage sludge and kitchen wastes) and decreased with increasing density of the earthworm population. The mean mass of cocoons was 0.0148 ± 0.0055 g (min. 0.0030 g, max 0.0330 g). This study presents some positive results of the laboratory breeding of earthworms in many different sewage sludges and discusses the effects of vermicomposting sludge at the sewage treatment plant in Brzesko. A concept of "ecological earthworm boxes" is put forward. The boxes may acquire economic significance through their contribution to the biodecomposition of organic wastes (e.g. those from households, canteens, restaurants, hotels, etc.) at the spot of their generation. It was shown that the difficulties with keeping earthworm populations in small containers like ecological boxes may be overcome by using a suitable feeding method. Feeding earthworms on wastes mixed with cellulose from cardboard boxes at a ratio of 1 :1/2 improved all parameters of the population (its size, biomass, mean biomass of adult individuals and the number of cocoons laid). in all the experiments described the earthworm populations stabilised organic wastes by turning them into vermicomposts. All the vermicomposts rich in nutrients available for plants, those from organic kitchen wastes being the richest (p--- 0.05). Vermicomposts obtained from cattle manure contained less nutrients and those from sewage sludge were the poorest. The vermicomposts produced did not differ in their pH which was close to neutral and varied between 6.5 and 7.5. Pronounced differences, however, were found in salt concentration. Vermicomposts from organic kitchen wastes had the highest salinity (significant in relation to manure vermicompost) — 8.1 g NaCI din-3 on average. This feature was unfavourable, but on the other hand kitchen waste vermicomposts were most rich in available nitrogen, phosphorus, potassium, calcium and magnesium. Lower salinity (5.6 g NaCl - dm-3 on average) was exhibited by vermicomposts from sewage sludge and the lowest (3.1) — by manure vermicomposts. The differences, however, were not statistically significant. It was found that the addition of cellulose to kitchen wastes lowered the concentration of salt in the vermicompost produced (p < 0.001). After six months of utilisation the salinity of the vermicompost obtained from kitchen wastes alone averaged 8.98 ± 1.98, while of that from wastes mixed with cellulose at I : 1/2 ratio — 6.69 ± 1.66. The addition of cellulose led also to the differences in the abundance of kitchen waste vermicomposts in some nutrients, namely phosphorus, potassium, calcium and magnesium, no such effect being observed in the case of nitrate nitrogen. An analysis of the mean levels of heavy metals in various types of vermicomposts showed (p = 0.05) that the vermicomposts produced from cattle manure and kitchen wastes contained less metals than the vermi¬compost from sewage sludge. The mean levels of heavy metals were the lowest in the vermicompost produced from selected organic kitchen wastes, but this was not statistically significant compared to the manure vermicompost. Of all types of vermicomposts, those based on sewage sludge were the most contaminated with metals.
|Other language title versions||Investigations into vermicomposting of organic wastes|
|Publisher||Uniwersytet Rolniczy im. Hugona Kołłątaja w Krakowie, MNiSW |
|Publishing place (Publisher address)||Kraków|
|Book series /Journal (in case of Journal special issue)||Zeszyty Naukowe Akademii Rolniczej im. H. Kołłątaja w Krakowie. Rozprawy, ISSN 1233-4189, (0 pkt)|
|Publication size in sheets||6|
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