Effect of waste activated sludge pretreatment methods to mitigate Gordonia foaming potential in anaerobic digestion

Abstract

In this study, waste activated sludge obtained from two full‐scale treatment plants with foaming issues was pretreated with acid/alkali treatment, acid‐phase fermentation, thermal treatment, ultrasonic treatment and metal salt treatment to investigate their effect on foam mitigation. Waste activated sludge was characterized for foaming index prior and after each pretreatment method. Among all pretreatment methods investigated, acid/alkali treatment and acid phase fermentation showed highest reduction of 53% in foaming and in inactivation of Gordonia amarae filaments. Pretreatment methods that resulted in sharp decrease in the foaming index concurred with higher amounts of dead foam formers as confirmed using live/dead staining and the PMA‐qPCR technique. Pretreating with iron(III)chloride gave good foaming reductions with 54% decrease in foaming potential at a concentration of 260 mg/L but did not result in a decline of foam formers as confirmed by live/dead staining. Ultrasonic treatment did not prove effective in lowering the foaming index or killing the G. amarae filaments.

Effects of the Combined Utilization of Ultrasonic/Hydrogen Peroxide on Excess Sludge Destruction

“…The experiment was carried out under room temperature (23~25 • C) and the energy density for ultrasonic treatment was 0.2 w/mL with a treatment frequency of 40 kHz. The effects of different initial pH (3.0, 5.0, 7.0, 9.0, 11.0), H 2 O 2 dosage (0, 0.1, 0.5, 1.0, 2.0, 5.0 mmol/L), initial sludge concentration (8,11,14,17,20 g/L), and ultrasonic treatment time (5, 10, 15, 20, 30 min) on sludge destruction were examined by single-factor experiments using sequential batch tests. ∆SCOD, lysis rate, ∆MLSS, and sludge reduction were used to evaluate the degree of sludge destruction.…”

“…Using excess sludge as a low-cost carbon source to improve denitrification efficiency for WWTP is an attractive option for researchers recently, as releasing its own organic matter could also facilitate the reduction of excess sludge. A number of studies have focused on sludge lysis technology, such as ozone [11], Fenton [12], acid-base [13,14], ultrasound [15], microwave [16,17], and mechanical [18]. Among those sludge lysis methods, ultrasonic pretreatment has been widely studied, as it is usually regarded as a simple method for operation, with wide application range, high efficiency, none secondary pollution [19] and can be combined with other processes [20,21].…”

Significant cost savings using a newly developed single‐process technology compared to conventional processes for treating high‐strength effluents

“…Anaerobic digestion (AD) is the best alternative to aerobic processes for the treatment of strong wastewaters (Gao et al, 2020; Garg et al, 2020; Ulgudur & Demirer, 2019; Xin et al, 2020), but there are some disadvantages, such as (i) biological nitrogen and phosphorus removal is not possible; (ii) requirement for further treatment with a subsequent aerobic treatment process in series to meet discharge requirements; and (iii) difficulties in achieving stable reactor performance as a result of sensitivity to fluctuations in temperature and operating conditions (Ambaye et al, 2021; Andalib et al, 2011; Metcalf & Eddy, 2014).…”