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.

The article presents the results of research from several years of exploitation of vermiculture plots located in the municipal sewage treatment plant in Zambrów. It is the only facility in Poland where vermicompost from municipal sewage sludge has been produced continuously since 2004 (for 16...

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...

Among sewage generated in wastewater treatment plants, dairy sewage sludge is the most suitable for environmental and farming application. Due to its physio-chemical content, it should be treated as raw material, not waste. Moreover, dairy sewage sludge is characterized by low heavy metals...

In Poland, low-input methods such as composting, vermicomposting, reed beds, willow energy and solar driers are more often being used in processing sewage sludge. The North eastern part of Poland has operated successfully for years using these methods. This paper presents the results of using...