Modern technologies designed to treat wastewater containing phosphorus compounds are based on the processes of adsorption and precipitation. In addition, more environmentally friendly and cheaper materials are being sought to ensure greater conformity with overarching assumptions of green chemistry and sustainable development. Against that background, this paper offers a review and analysis of available information on the considered reactive materials that have the capacity to remove phosphorus from wastewater. These materials are categorised as natural (with a sub-division in line with the dominant sorption groups of Al/Fe or Ca/Mg), waste, or man-made. Notably, most studies on sorbents have been carried out in laboratory systems via experimentation under static conditions. Among the natural materials, opoka has the highest sorption capacity of 181.20 g P/kg, while red mud (in the waste material category) is most efficient at binding phosphorus with a level of 345.02 g P/kg. Finally, among the group of commercial materials, Rockfos® has the highest sorption capacity of 256.40 g P/kg. In addition, this paper recognises the effect of composition, pH, and physical properties on a reactive material’s capacity to absorb phosphorus, as well as the possibility for further potential use in the production of fertilisers.

Abstract. Aerobic Granular Sludge (AGS) technology becomes a very competitive method to activated sludge system. Its main advantages include: high energy efficiency and low investment costs. Despite this fact, intensive research on biogranulation optimization are still carried out, both at laboratory and technical scale. In order to intensify the AGS technology, new methods of biogranulation and ways of improving the stability of aerobic granules are sought. So far, several studies have been conducted in this area, with using among others: chemical coagulants, dosage fragments of granules and powdered materials. The aim of this study was to evaluate the impact of powdered keramsite on the feasibility of rapid aerobic granulation in a GSBR reactor with a minimum-optimum organic loading rate (OLR). The research presents an effective way of cultivating stable aerobic granules in a Granular Sequencing Batch Reactor (GSBR) under specific technological parameters.

The improvement of energy efficiency ensuring high nutrients removal is a great concern for many wastewater treatment plants (WWTPs). The energy balance of a WWTP can be improved through the application of highly efficient digestion or its intensification, e.g., through the introduction of the co-substrates with relatively high energy potential to the sewage sludge (SS). In the present study, the overview of the energetic aspect of the Polish WWTPs was presented. The evaluation of energy consumption at individual stages of wastewater treatment along with the possibilities of its increasing was performed. Additionally, the influence of co-digestion process implementation on the energy efficiency of a selected WWTP in Poland was investigated. The evaluation was carried out for a WWTP located in Iława. Both energetic and treatment efficiency were analyzed. The energy balance evaluation of this WWTP was also performed. The obtained results indicated that the WWTP in Iława produced on average 2.54 GWh per year (7.63 GWh of electricity in total) as a result of the co-digestion of sewage sludge with poultry processing waste. A single cubic meter of co-substrates fed to the digesters yielded an average of 25.6 ± 4.3 Nm3 of biogas (between 18.3 and 32.2 Nm3/m3). This enabled covering the energy demand of the plant to a very high degree, ranging from 93.0% to 99.8% (98.2% on average). Importantly, in the presence of the co-substrate, the removal efficiency of organic compounds was enhanced from 64% (mono-digestion) to 69–70%.

This study aimed to evaluate and compare the physical, chemical and biological properties of aerobic granular sludge from reactors with the addition of different powdered mineral materials. These properties have a significant impact on the efficiency of systems in which the biomass in granular form is used. Four identical granular sequencing batch reactors (GSBRs) were adopted for the research performed on a laboratory scale (R1—control reactor; R2, R3 and R4—with materials, PK, PG and PL respectively). The results indicate that the addition of powdered mineral materials improved the properties of biomass in reactors. The SVI5/SVI30 ratio values were significantly lower in the reactors with added materials (approx. 1.3 ± 0.3). The mean values of the sludge volume index at 30 min were the lowest in the R2 (39.8 ± 8.6 mL/g) and R4 (32.8 ± 10.7 mL/g) reactors. The settling velocity of biomass was the highest in the R2 reactor (15.4 ± 6.1 m/h). In the early days of the study, the highest extracellular polymeric substances (EPS) content was found in the biomass from the reactors to which the materials with higher Ca and Mg content were added (380.18–598.30 mg/g MLVSS). The rate of specific oxygen uptake (SOUR) by biomass indicated an insufficient biomass content in the R1 reactor—to 7.85 mg O2/(g MLVSS∙h)—while in the reactors with materials, the SOUR values were at the higher levels.

In wastewater treatment, aerobic granular sludge (AGS) technology is a relatively new alternative to the activated sludge method. The biogranulation of biomass ensues when appropriate environmental conditions in a reactor are ensured, and one of the factors determining this is the organic loading rate (OLR). As a literature review suggests, the optimal values of OLR for AGS technology are in the range of 2.50-7.50 g COD/(dm 3 •d), the aim of the work detailed here was to evaluate the impact of powdered ceramsite on biogranulation in two Granular Sequencing Batch Reactors (GSBRs) in which OLR was equal to just 2.10 g COD/(dm 3 •d) (R1) and 1.0 g COD/(dm 3 •d) (R2). The research was carried out in laboratory scale with using synthetic wastewater containing different concentration of organic compounds. In the course of the research, a more intensive process of biogranulation was noted in reactor R1, and mean diameters of granules on the last day of experimentation were 962 and 274 µm for R1 and R2, respectively. While the organic loading rate equal to 2.10 g COD/(dm 3 •d) could allow granule formation, the results also pointed that lower food-to-microorganism (F/M) ratios favour biogranulation. This parameter was indirectly affected by the application of powdered ceramsite, because the powdered material improved the sludge sedimentation properties (average values of SVI 30 being 30.1±12.8 and 36.9±10.9 cm 3 /g). The result of this was more-limited leaching of biomass from reactors (with average values for MLVSS at 4.37±1.23 and 3.03±0.67 g/dm 3).