A Low Cost Fe3O4–Activated Biochar Electrode Sensor by Resource Utilization of Excess Sludge for Detecting Tetrabromobisphenol A

Owing to its ubiquity in natural water systems and the high toxicity of its accumulation in the human body, it is essential to develop simple and low-cost electrochemical sensors for the determination of 3,3′,5,5′-tetrabromobisphenol A (TBBPA). In this work, Fe3O4–activated biochar, which is based on excess sludge, was prepared and characterized using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR) and BET analysis to analyze its basic features. Subsequently, it was used to fabricate an electrochemical sensor for the detection of TBBPA. The electrochemical test results revealed that the Fe3O4–activated biochar film exhibited a larger active surface area, a lower charge transfer resistance and a higher accumulation efficiency toward TBBPA. Consequently, the peak current of TBBPA was significantly enhanced on the surface of the Fe3O4–activated biochar. The TBBPA sensing platform developed using the Fe3O4–activated biochar composite film, with relatively a lower detection limit (3.2 nM) and a wider linear range (5–1000 nM), was successfully utilized to determine TBBPA levels in water samples. In summary, the effective application of Fe3O4–activated biochar provided eco-friendly and sustainable materials for the development of a desirable high-sensitivity sensor for TBBPA detection.

Efficiency studies of modified IFAS-OSA system upgraded by an anoxic sludge holding tank

An upgraded integrated fixed-film activated sludge-oxic settling anoxic (IFAS-OSA) system is a new technology for reducing nutrients and excess sludge. The results showed that the average TN removal efficiency of the IFAS-OSA system was gradually increased up to 7.5%, while the PO4–3-P removal efficiency increased up-to 27%, compared with that of the IFAS system. The COD removal efficiency of the IFAS-OSA system was slightly increased up-to 5.4% and TSS removal efficiency increased up to 10.5% compared with the control system. Biomass yield coefficient (Yobs) in the IFAS and IFAS-OSA systems were 0.44 and 0.24 (gr MLSS/ gr COD). Hence, sludge production decreased by 45%. The average SVI was decreased by 48% in IFAS-OSA system compared with IFAS. This study demonstrated the better performance of the IFAS-OSA system compared to that of the IFAS system.

CO-DIGESTION OF GREASY WASTE AND MBR SLUDGE USING BIO-AUGMENTED PSEUDOMONAS PUTIDA: EFFECT OF BUFFERING AGENTS

This study aims to investigate the bio-augmentation of Pseudomonas putida for initializing fat, oil,and grease (FOG) biodegradation in a co-digestion of the greasy waste and the membranebioreactor (MBR) excess sludge. The MBR sludge could be an additional nitrogen sourceconcurrently as a waste matrix fluidizer. Three rounds of a fed-batch of an HRT of 56-71 dayswere carried out. The first (B1) and second (B2) batches using phosphate (Na2HPO4) solution as abuffering system. It showed that the digesters with bio-augmented P. putida could remove moreFOG than that of the control. In the third batch (B3), the buffering solution was changed tobicarbonate (NaHCO3) with the interval bio-augmentation of P. putida in different doses; the 250ml (B3, T-250) and the 1000 ml (B3, T-1000) of P. putida culture every two weeks dosing. Thehighest FOG removal was found in both conditions with the removal efficiency of 79.77%. Thisstudy suggests that bicarbonate was a suitable buffer in the co-digestion process for the intervalbio-augmentation of P. putida. Moreover, it showed that a higher interval dose (B3, T-1000) of P.putida gave a more methane production rate of 981.08 ml/g TVS. d compared to the lower dose ofB3(T-250) with 353.75 ml/g TVS. d.