Efficient Low-Cost Anaerobic Treatment of Wastewater Using Biochar and Woodchip Filters

Korbinian Kaetzl,Manfred Lübken,Tito Gehring,Marc Wichern

doi:10.3390/w10070818

Korbinian Kaetzl, Manfred Lübken + Show 2 more

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https://doi.org/10.3390/w10070818

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Journal: Water	Publication Date: Jun 21, 2018
Citations: 53	License type: CC BY 4.0

Affiliation: Ruhr University Bochum

Abstract

Access to improved sanitation is often lacking in many low-income countries, and approximately 90% of the sewage is discharged without treatment into receiving water bodies. The aim of this study was the development and evaluation of an efficient low-cost wastewater treatment system for developing countries. Biochar and woodchips, potential locally available and inexpensive materials, were used for anaerobic wastewater filtration and their suitability evaluated in comparison to gravel as a common reference material. Filters were fed with raw sewage from a municipal full-scale wastewater treatment plant in Germany at 22 °C room temperature with a hydraulic loading rate (HLR) of 0.05 m∙h−1. This resulted in a mean organic loading rate (OLR) of 252 gCOD∙m−3∙d−1 and a mean organic surface load of 456 gCOD∙m−2∙d−1. To determine the influence of different filter materials, the removal efficiency of chemical oxygen demand (COD), total organic carbon (TOC), turbidity, and faecal indicator bacteria (FIB) E. coli and enterococci were tested. It was found that COD (up to 90%), TOC (up to 80%), FIB (up to 1.7 log10-units), and turbidity (effluent turbidity below 35 NTU) could be significantly reduced. The findings of this study demonstrate the potential of anaerobic filters (AFs) for wastewater treatment in low-income countries to reduce water pollution and comprehensively improve water quality. The performance of biochar filters was significantly better over the entire experiment compared to woodchip and gravel filters with respect to COD, TOC, turbidity, and FIB removal, indicating the superior properties of biochar for wastewater treatment.

Highlights

Insufficient access to sanitation and clean water is one of the most prevalent problems affecting people worldwide [1]
The measurement of hydraulic residence time and tracer recovery provides important information, as they affect the contact time of the wastewater with the filter material as well as with the biofilm that develops on its surface
The theoretical hydraulic retention times (HRTs) in the columns were calculated by the porosity and hydraulic loading rate (HLR) (Table S3) and compared with NaCl tracer tests (Figure S1)

Summary

Introduction

Insufficient access to sanitation and clean water is one of the most prevalent problems affecting people worldwide [1]. Due to global population and economic growth, rapid urbanization, and climate change, water scarcity is expected to increase in coming decades, within developing countries [2,3]. The situation is dramatically aggravated by the fact that approximately 2.4 billion people still do not have access to improved sanitation, and approximately 90% of the sewage in low-income countries is discharged without treatment into surface waters [4,5]. There is urgent demand for the development and implementation of low-cost, simple, compact, and efficient wastewater treatment systems for a sustainable reduction of water pollution. To our knowledge, Water 2018, 10, 818; doi:10.3390/w10070818 www.mdpi.com/journal/water

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