No abstract

Six-month experiments have been carried out using pilot installations of low-budget methods of sewage sludge treatment. Sewage sludge was processed using vermiculture or plants such as willow or reed. The study was also conducted in a solar dryer. In some parts of the research, effective microorganisms were used. The results of the sediment research, including: contents of organic and mineral matter, hydration reaction, contents of nitrogen and phosphorus, as well as the indicators of the sanitary condition, were presented. The results confirmed a perceptible influence of the effective microorganisms on the structure of the dry mass of dairy sewage dewatered on reed and willow plots or transformed into vermicompost. A slight, however, apparent difference in a faster and more effective mineralization of organic substances contained in the sludge after half a year of processing, as well as significant reduction of the number of potential pathogenic bacteria was observed.

Reject water is a by-product of every municipal and agro-industrial wastewater treatment plant (WWTP) applying sewage sludge stabilization. It is usually returned without pre-treatment to the biological part of WWTP, having a negative impact on the nitrogen removal process. The current models of pollutants removal in constructed wetlands concern municipal and industrial wastewater, whereas there is no such model for reject water. In the presented study, the results of treatment of reject water from dairy WWTP in subsurface vertical flow (SS VF) and subsurface horizontal flow (SS HF) beds were presented. During a one-year research period, SS VF bed reached 50.7% efficiency of TN removal and 73.8% of NH4+-N, while SS HF bed effectiveness was at 41.4% and 62.0%, respectively. In the case of BOD5 (biochemical oxygen demand), COD (chemical oxygen demand), NH4+-N, and TN (total nitrogen), the P-k-C* model was applied. Multi-model nonlinear segmented regression analysis was performed. Final mathematical models with estimates of parameters determining the treatment effectiveness were obtained. Treatment efficiency increased up to the specific temperature, then it was constant. The results obtained in this work suggest that it may be possible to describe pollutant removal behavior using simplified models. In the case of TP (total phosphorus) removal, distribution tests along with a t-test were performed. All models predict better treatment efficiency in SS VF bed, except for TP.

Assessment of the assimilability of elements contained in sewage sludge can only be carried out if their fractions, by means of which the chemical form of the element can be identified, are determined. The total content of heavy metals only makes it possible to determine whether the sludge meets the legal requirements and can be used, inter alia, for reclamation, in agriculture or for the adaptation of land to specific needs that result from waste management plans. Therefore, when planning the agricultural use of sewage sludge, attention should be paid above all to the heavy metal fractions contained in it. This is due to the fact that plants do not assimilate every form of element to the same extent. The research and analysis carried out indicate that the metals were most closely related to fractions IV and III, for example they formed connections with silicates, as well as sulphides and organic matter. The metal forms available to plants occupied a small percentage of the total heavy metal content. It was noted that with the metastable fraction of lead increased along with population equivalent. Furthermore, the population equivalent value did not affect the distribution of individual heavy metal fractions in the sludge.

The present paper was aimed at determining the influence of particular methods and biological processes, including the application of Effective Microorganisms, on the change in characteristics of the treated dairy sewage sludge, especially when discussing the changes in the content of nutrients and macroelements. The purpose of the conducted research was to specify the possibility of using natural biological methods of dairy sewage sludge treatment and adapting it to environmental, especially farming use. Diagnostic research on the content of sewage sludge from dairy wastewater treatment plants in the northeastern region of Poland has been conducted since the 1990s. On the basis of the results and the assessment of the possibility of agricultural utilization of dairy sewage sludge, the objectives for research on sludge treatment were established. The research facilities were located on the premises of Municipal Wastewater Treatment Plant in Zambrów. The choice of location for the research facilities was guided by the possibility of supplying the same sludge from dairy wastewater treatment. The excess sludge from biological dairy sewage treatment, which was aerobically stabilized in separate chambers, was used in the research. In all of the facilities where sludge was treated with biological methods, Effective Microorganisms (EM) were also used for comparison. In the years 2010-2013, the research was conducted in the research facilities (own project) constructed and launched in 2010, which were planted with phragmites and common osier. In the years 2010-2012, the research was conducted in the research facilities (own project) constructed and launched in 2010, i.e. vermiculture patches. The conducted research was comprehensive and the obtained experiment results point to the necessity of continuation and further development of research concerning the content transformation in dairy sewage sludge during its biological treatment. Establishing the role of microorganisms present in the EM formula on the processes and transformations occurring in biologically treated sewage seems to be of exceptional importance. The innovativeness of the research lay mainly in a very comprehensive range of natural biological methods of treatment applied for the same sewage sludge coming from dairy wastewater treatment plants. The conducted research points to the influence of the EM formula on vital changes in the content of macroelements in the biologically treated dairy sewage sludge. The most important impact (from the point of view of the number of parameters and the change in size as a result of applying EM formula) was observed in reference to the vermicomposting process with the use of earthworms and long-term stabilization in reed beds. The statistical assessment methods applied to the obtained results of own research (Wilcoxon and Spearman tests, Spearman's rank correlation coefficient) point to a significant influence of the EM formula on different "behavior" of many analyzed characteristics of the treated sludge.