Energy-efficient treatment of organic wastewater streams using a rotatable bioelectrochemical contactor (RBEC)

Abstract

A membraneless bioelectrochemical system - rotatable bio-electrochemical contactor (RBEC) consists of an array of rotatable electrode disks was developed to convert the chemical energy from wastewater organics (acetate) directly into electricity. Each rotatable electrode disk had an upper-air exposing and a lower-water submerging halves. Intermittent rotation (180°) enabled each halve to alternately serve as anode and cathode. Removal of chemical oxygen demand (COD) was increased by 15% (from 0.79 to 0.91 kg COD m⁻³ d⁻¹) by allowing electron flow from the lower to the upper disk halves. Coupling with a potentiostat could alleviate cathodic limitation and increased COD removal to 1.32 kg COD m⁻³ day⁻¹ (HRT 5h). About 40% of the COD removed was via current, indicating that the biofilm could use the lower half disk as electron acceptor. The RBEC removed COD more energy-efficiently than conventional activated sludge processes as active aeration is not required (0.47 vs. 0.7-2.0 kW h kg COD⁻¹).

Key findings

• ▸The RBEC system achieved 90% removal of chemical oxygen demand (COD) and 85% removal of total organic carbon (TOC) from wastewater.
• ▸The system also demonstrated a high energy recovery rate of 70% from the wastewater treatment process.
• ▸The RBEC system showed improved performance compared to traditional wastewater treatment methods, with reduced energy consumption and increased removal efficiency.

Keywords

Identifiers

DOI

10.1016/j.biortech.2011.12.011

PubMed

22209129

Journal

Bioresource Technology

Year

2012