Application of alternative carriers without protected surface in moving bed biofilm reactor for domestic wastewater treatment

Biological reactors with immobilized biomass on free carriers have provided new perspectives for wastewater treatment, once they reduce the system size and increase the treatment capacity. In this study, the performance of three Moving Bed Biofilm Reactors (MBBR) using different carriers (with and without protected surface area) were evaluated for domestic wastewater treatment in continuous flow. Each MBBRs (i.e., R1, R2, and R3) was filled at a ratio of 50% with high-density polyethylene carriers with different characteristics: both R1-K1 and R2-Corrugated tube with protected surface and R3-HDPE flakes without protected surface. Chemical oxygen demand (COD) removal of 80 ± 5.0, 80 ± 3.5, and 78 ± 2.4% was achieved by R1, R2, and R3, respectively. The oxygen uptake by biofilm attached on the carriers was 0.0079 ± 0.0013, 0.0033 ± 0.0015, and 0.0031 ± 0.0026 μg DO·mm−2 for the K1, corrugated tube, and HDPE flakes, respectively. No significant differences were observed between the performance of the three MBBRs in terms of physico-chemical parameters (alkalinity, pH, and dissolved inorganic carbon) and COD removal. Results showed that the carrier type and its characteristics (total area and with/without protected area) did not affect the organic matter removal. Thus, the carrier without a protected surface in MBBR could be a promising low-cost option for domestic wastewater treatment.

Progress in Domestic Wastewater Treatment, Resource Recovery and Energy Generation Using Microbial Fuel Cell

Microbial fuel cells (MFC) are emerging as a versatile eco-friendly bioelectrochemical system (BES) that utilizes microorganisms as biocatalysts to simultaneously convert chemical energy in the chemical bond of organic and inorganic substrates into bioelectricity and treat wastewater. The performance of MFC depends on the electroactive microorganisms, popularly known as exoelectrogens, the loading rate of organic substrate, pH, MFC configurations, hydraulic retention time, and temperature. In most cases, the performance of MFC can be evaluated by measuring chemical oxygen demand (COD) removal efficiency, Coulombic efficiency and MFC power density output. To date, the most common MFC’s reactor designs are single-chamber MFC, double-chambers MFC, and stacked-MFC configurations. Generally, considerable developments in MFC systems for waste treatment, renewable energy generation and resource recovery have been made in the last two decades, despite critical challenges of capital cost investment, and low efficiency for large scale applications are impeding MFC from commercialization. This mini-review chapter provides a comprehensive assessment of principles and configurations of MFC, treatment of domestic wastewater, energy generation, and resource recovery by MFC and challenges of MFC. I believe the information provided in this chapter will enlighten the current and future prospects of versatile applications of MFC during domestic wastewater treatment.