Application of a Low Cost Ceramic Filter for Recycling Sand Filter Backwash Water

Md Shafiquzzaman,Abdullah Al-Mahmud,Husnain Haider,Saleem Alsaleem

doi:10.3390/w10020150

Abstract

The aim of this study is to examine the application of a low cost ceramic filter for the treatment of sand filter backwash water (SFBW). The treatment process is comprised of pre-coagulation of SFBW with aluminum sulfate (Alum) followed by continuous filtration usinga low cost ceramic filter at different trans-membrane pressures (TMPs). Jar test results showed that 20 mg/L of alum is the optimum dose for maximum removal of turbidity, Fe, and Mn from SFBW. The filter can be operated at a TMP between 0.6 and 3 kPa as well as a corresponding flux of 480–2000 L/m2/d without any flux declination. Significant removal, up to 99%, was observed forturbidity, iron (Fe), and manganese (Mn). The flux started to decline at 4.5 kPa TMP (corresponding flux 3280 L/m2/d), thus indicated fouling of the filter. The complete pore blocking model was found as the most appropriate model to explain the insight mechanism of flux decline. The optimum operating pressure and the permeate flux were found to be 3 kPa and 2000 L/m2/d, respectively. Treated SFBW by a low cost ceramic filter was found to be suitable to recycle back to the water treatment plant. The ceramic filtration process would be a low cost and efficient option to recycle the SFBW.

Highlights

In current practice, ground water is being treated by conventional treatment processes including oxidation, coagulation, flocculation, sedimentation, and sand filtration
The accumulated contaminants are detached from the filter, and the resulting water is called sand filter backwash water (SFBW) that contains a high amount of suspended solid, colloidal materials, inorganic metals (Fe, Mn, and Al), natural organic matter, bacteria, viruses, invertebrates, and protozoa
The aim of the current study is to investigate the feasibility of using a simple ceramic-filter coupled with the coagulation and flocculation process to treat the SFBW and to produce high-quality recyclable water

Summary

Introduction

Ground water is being treated by conventional treatment processes including oxidation, coagulation, flocculation, sedimentation, and sand filtration. To maintain the efficient flux in filtration, it is essential to perform regular backwashing of the sand filter (one/twice a day). During this process, a large amount of wastewater is produced, from the sand filter backwashing. On average, approximately 2–10% of drinking water produced by conventional water treatment plant (WTP) is used for backwashing [1]. The accumulated contaminants are detached from the filter, and the resulting water is called sand filter backwash water (SFBW) that contains a high amount of suspended solid, colloidal materials, inorganic metals (Fe, Mn, and Al), natural organic matter, bacteria, viruses, invertebrates, and protozoa

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Conclusion