Catalytic activity of low cost materials for pollutants abatement by Fenton's process

• Low cost materials were tested as catalysts in Fenton's process.
• Iron shavings were selected as most active for synthetic and real OMW treatment.
• Process was efficient both in batch and continuous conditions.
• Biodegradability was enhanced and eco-toxicity was depleted.
• This methodology integrates waste management and wastewater treatment.

The main objective of this study was to investigate the catalytic activity of three low cost materials (sepiolite, red volcanic rock and iron shavings) during the Fenton-like process on the treatment of simulated and actual olive mill wastewaters. Among the catalysts screened, iron shavings (ZVI) was the most promising, as it was the catalytic material that attained the best performance. Besides it as the advantage of being a waste of iron processing industry, not needing any modification before use. Since the Fenton's reaction efficiency is dependent on ZVI and H2O2 concentrations and as well as initial pH, the effect of these parameters was analyzed in batch tests for a synthetic phenolic effluent treatment. From the results it was concluded that the most interesting removals (94% of TPh, 54% of COD and 60% of TOC) were reached using [ZVI]=40 g/L, [H2O2]=35 mM and pH=3. This effectiveness was confirmed when Fenton's peroxidation under the same conditions was applied to an actual olive mill wastewater (OMW). The impact of this methodology over the effluents biodegradability and toxicity was still grasped.Furthermore, the stability of ZVI under continuous conditions was also tested when applied to both the synthetic phenolic effluent and real OMW treatments in a fixed bed reactor using the H2O2 load and pH optimized in batch reaction; high activity was still observed after 168 h of operation of the column when synthetic phenolic effluent was treated, since TPh, TOC and COD removals remained about 73%, 39% and 44%, respectively. These results show that ZVI can be used as low cost catalytic material in Fenton reaction for the treatment of OWM in batch or continuous reaction with high catalytic stability.