The Impact of Electric Current for Sewage Sludge Characteristics from Anaerobic Sequencing Bio-Electrochemical Treatment of Sewage Generated During Soilless Tomato Cultivation

Abstract

The aim of the present study was to determine: the impact of electric current density on the quantity and quality of sewage sludge produced in anaerobic sequencing bio-electrochemical reactor (AnSBBER) with an iron electrode during the treatment of drainage from soilless cultivation of tomatoes. Direct electric current (DC) effect was de - termined at its following densities (J): 0.63 A/m 2 (R1), 1.25 A/m 2 (R2), 2.5 A/m 2 (R3), and 5 A/m 2 (R4). Sodium acetate in (C:N) ratio of 1.0 was supplied to the reactors to ensure the proper biofilm development. Contents of elements (K, P, S, Na, Al, Cu, Fe, Mn, Mo, Zn, Mg, C, N and Ca) in the biofilm were determined. Additionally, the content of total suspended solids and the percentage share of volatile suspensions (VSS) in the sludge were determined. The study showed that the organic matter content in the sludge corresponded to the values typical of the stabilized sludge (up to 28.8% d.m. in R2).The increase in electric current density caused an increase in the concentration of phosphorus in the formed sludge (from 6.34 to 8.00% d.m. in 0.63 and 5.00 A/m 2 , respectively). The analyzed sludge, compared to municipal sludge from wastewater treatment plants with biological reactors and activated sludge chambers, is richer in such elements as phosphorus, nitrogen, calcium, magnesium, potassium, sodium, and iron.