# Optimization of moving bed biofilm reactor (MBBR) operation for biodegradation of Diuron herbicide and organic load removal from synthetic wastewater

## TL;DR

This study shows that a Moving Bed Biofilm Reactor can efficiently remove the herbicide Diuron and organic pollutants from wastewater, but additional treatment is needed to meet strict environmental standards.

## Contribution

The study identifies optimal operational parameters for Diuron and COD removal in MBBR systems and highlights their suitability as a pre-treatment step.

## Key findings

- Diuron removal of 98.68% and COD removal of 93.4% were achieved under optimized conditions.
- Residual Diuron concentrations remained above regulatory limits, suggesting MBBR is best used as a pre-treatment.
- The system performed robustly under high Diuron loads and variable organic loading.

## Abstract

This study evaluates the performance of a laboratory-scale Moving Bed Biofilm Reactor (MBBR) for the biological removal of the herbicide Diuron and simultaneous reduction of chemical oxygen demand (COD) from synthetic wastewater. The reactor was operated under varying hydraulic retention times (HRT = 24, 48, and 72 h), carrier fill fractions (30%, 50%, and 70%), influent COD levels (500–1500 mg L−1), and Diuron concentrations (10–25 mg L−1). Results show that increasing HRT and carrier fill fraction significantly enhanced treatment efficiency. The highest Diuron removal (98.68%) and COD removal (93.4%) were achieved at HRT = 71.7 h, carrier fill fraction = 52.6%, organic load = 502.4 mg L−1, and Diuron concentration = 10.13 mg L−1. Statistical analysis (ANOVA, p < 0.05) confirmed that HRT, fill fraction, Diuron concentration, and organic load all significantly influenced removal performance. Although the MBBR demonstrated high efficiency for Diuron degradation, residual concentrations under even optimal conditions (e.g., ∼212 µg L−1 from 10 mg per L influent) remain well above regulatory thresholds (e.g., EU limit: 0.1 µg L−1), indicating that MBBR is best suited as a pre-treatment step prior to advanced polishing technologies. The system proved robust under elevated Diuron loads (up to 25 mg L−1) and variable organic loading, highlighting its potential for treating pesticide-laden industrial and agricultural effluents when integrated into a multi-barrier treatment train.

The MBBR achieved 98.68% Diuron removal under optimized conditions, although the effluent still exceeded regulatory limits.