Evaluation of Titanium Dioxide Modified Biochar in a Moving Bed Biofilm Reactor for Wastewater Treatment

Abstract

Wastewater treatment is essential for reducing environmental pollution and improving effluent quality. Conventional biological treatment technologies, including the Moving Bed Biofilm Reactor (MBBR) are widely used for organic pollutant removal; however, their performance depends on wastewater characteristics, biofilm development, and operating conditions. The present study evaluates the potential application of titanium dioxide (TiO?)-modified rice husk biochar in an MBBR system for wastewater treatment. The proposed approach combines the adsorption properties of biochar with the potential photocatalytic activity of TiO? to enhance contaminant removal. A laboratory-scale reactor with a working volume of 15 L was used to investigate treatment performance under controlled operating conditions, with a conventional MBBR serving as the control. Wastewater samples were collected from selected sources including a sewage treatment plant, a milk-processing facility, and industrial sources. Treatment performance was assessed primarily through biochemical oxygen demand (BOD), chemical oxygen demand (COD), and total dissolved solids (TDS). The study also considered the influence of reactor configuration, carrier characteristics, aeration, sunlight exposure, and biofilm development on treatment performance. The principal evaluation outcomes are the comparative removal efficiencies of BOD, COD, and TDS in the conventional and TiO?-modified biochar systems. This investigation provides a basis for assessing the practical applicability of TiO?-modified biochar in hybrid biological treatment and for identifying the operational and material-related factors requiring further investigation. Further quantitative validation is necessary to establish the magnitude of performance improvement, material stability and suitability for practical wastewater treatment applications.

Introduction

Wastewater treatment is essential for protecting the environment and preventing pollutants from contaminating natural water bodies. Conventional biological treatment methods, such as the Moving Bed Biofilm Reactor (MBBR), use microorganisms attached to carrier media to break down biodegradable organic matter. However, their performance can be affected by pollutant concentration, wastewater composition, operating conditions, and biofilm development.

This study focuses on evaluating titanium dioxide (TiO?)-modified biochar in an MBBR system to improve wastewater treatment efficiency. Biochar, produced by heating biomass in the absence of oxygen, can adsorb various contaminants, while TiO? is a semiconductor material known for its photocatalytic properties under suitable light conditions. Combining these materials may support pollutant removal through adsorption and photocatalysis alongside biological treatment.

The literature review highlights previous research on MBBR technology, biofilm development, biochar-based adsorbents, and TiO?-based photocatalysts. However, limited experimental evidence establishes how TiO?-modified biochar performs within an MBBR system, particularly in terms of Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD), and Total Dissolved Solids (TDS). Further investigation is also needed to assess biofilm compatibility, material stability, and the potential release of particles into treated water.

The experimental methodology involves collecting wastewater samples from different sources, including the sewage treatment plant (STP) at Baldev Nagar, Ambala, Vita Milk Plant, and nearby industrial facilities in Lalru. Five laboratory-scale reactors, each with a capacity of 15 litres, were constructed using 5 mm-thick acrylic sheets and a carrier filling ratio of approximately 40–45%. The experimental setup includes three reactors for TiO? powder treatments, one for TiO?-coated carrier media, and one control reactor. The coated media undergo a ten-day preconditioning period to support biofilm formation. Natural sunlight between 10:00 AM and 3:00 PM is used for photocatalytic exposure, with a UV-visible spectrometer employed to monitor the experimental conditions.

The main objectives are to compare conventional MBBR treatment with TiO?-modified biochar treatments, measure BOD, COD, and TDS before and after treatment, calculate pollutant-removal efficiencies, and assess the practical limitations and stability of the modified material.

Conclusion

TiO?-modified biochar presents a potential material for investigation in MBBR-based wastewater treatment because it combines the adsorption characteristics of biochar with the potential photocatalytic properties of titanium dioxide. Existing literature supports the investigation of TiO? biochar composites for pollutant removal and establishes the importance of carrier properties and biofilm development in MBBR systems.

References

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Copyright

Copyright © 2026 Raveena Chauhan, Ms. Mandeep Saini. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.