Advanced Research on Polymer Floating Carrier Application in Activated Sludge Reactors

Abstract

This research estimates the efficiency of domestic wastewater treatment in the removal of organic pollutants and nitrogen compounds with a two-stage treatment sequence (an activated sludge reactor in the first stage, and a trickling filter in the second stage), and with the application of floating carriers in the activated sludge reactor. The materials “Polyvom”, “Polystyrene” and “Bioballs” were adopted as floating carriers with previously determined filling ratios in the reactor volume of 10%, 20% and 20%, respectively. After the first stage of the study, it was found that the most effective treatment was achieved using the “Polyvom” material. Therefore, only this floating carrier was considered in the second and third stages of the study. Within the stages of the research, lab-scale benches operated under different operation modes of the treatment sequence. At the end of the study, it was possible to achieve the following levels of purification: BOD5 (2.1 mg/L), NH4 (0.4 mg/L), NO2 (1.0 mg/L), and NO3 (25 mg/L). The mean values of the concentrations of BOD, NH4, and NO3 met the requirements, but the concentration of NO2 exceeded the requirements (1.0 mg/L vs. 0.08 mg/L). These results were achieved under a hydraulic retention time in the activated sludge reactor of 8 h, and the MLSS for the free-floating and immobilized activated sludge was 0.2 and 0.9 g/L, respectively.

Assessment of Wastewater Treatment Plant Upgrading with MBR Implementation

“…The majority of municipal WWTPs were built between the 1970s and 1990s, and their design method was focused on the removal of only organic pollutants (carbon) and suspended solids [ 16 , 22 ]. Upgrades are usually based on existing information about treatment facilities.…”

“…The UCT-MBR* bar shows the overall specific energy consumption if membrane costs are presented as specific energy consumption. It can be seen that the transition to an advanced scheme of treatment leads to a significant growth in energy consumption [ 16 , 33 ]. The application of an MBR means less tank volume for the ASR, which reduces the energy consumption for aeration in the ASR; however, membrane aeration is an extremely energy-consuming process.…”

“…As already noted in various studies, the rate of wastewater disposal has decreased significantly recently [2,16]. Currently, in the Russian Federation, the typical daily SRWP at a level of 180 L per capita is admitted for calculations.…”

“…This suggests that with a decrease in capacity and a larger range of the SRWP, the influence of concentrated effluents increases. The SRWP decrease means that 25–35% of the WWTP with a capacity of more than 100 k m 3 /day is receiving wastewater, which should be assessed as highly concentrated in the conditions of the Russian Federation [ 16 ]. In Western Europe, especially Germany, with the SRWP value in many localities below 80 L per capita, the concept of highly concentrated wastewater is significantly different: it is characterized by at least twice the pollution values for the TSS and BOD 5 .…”