Hanene Akrout

Title : Comparative assessment of different treatment scenarios applied to wastewater from agri-food industry towards circular economy

Abstract:

In contemporary industrial wastewater management, there's a pressing need to mitigate the impact of discharged wastewater on the environment. Consequently, extensive research is being conducted to explore sustainable alternatives to conventional treatment methods. These technologies aim the recycling and reuse of wastewater, particularly in regions facing water scarcity.

This study investigates the treatment of poultry slaughterhouse wastewater effluents (PSWW), characterized by its complex composition of fats, proteins and fibers, through the application of different treatment methods namely: The physico-chemical treatment using a coagulation-flocculation process (C/F) advanced oxidation treatment using bipolar Si/BDD cell (EO), the combination of CF and EO.

The in-situ scenario described the existing treatment in the industry using a first Aerated Submerged Fixed-Film (ASFF) reactor with a capacity of 80m³ followed by six other reactors in series with a capacity of 20m³each. The station allows the treatment of 120 m³.d^-1 with Hydraulic retention time of 1d. The ASFF reactor showed a good performance for the removal of organic pollutant with a COD removal efficiency of 86.7%. Moreover, the TWW presented a low concentration in terms of nitrate and nitrite which fit with the Tunisian norms of discharge into the sewer network. However, the quality of the TWW doesn’t fit with the norms of reuse in irrigation.

The scenario 1 investigated the treatment of the raw PSWW with C/F under optimum conditions determined in previous work with the response surface methodology (coagulant dose of FeCl₃ = 400 mg/L, floculant dose of polyacrylamide = 46.2 mg/L and pH = 5.9). The C/F treatment allowed the achievement of COD removal efficiency of 80% with a final concentration of 352 mg/L and an increase in Chloride concentration which don’t fit with the reuse norm in irrigation. The scenario 2 consisted on the treatment of the PSWW with EO using bipolar Si/BDD cell. For a current density of 50 mA cm^-2 and electrolysis time of 3 hours, the COD removal efficiency was about 94,2% with a final concentration of 104 mg L^-1. The electric energy consumption was 158.18 kWh. Kg COD⁻¹ removed.

The hybrid treatment which presented the scenario 4 consisted of the application of the EO for the pretreated PSWW with C/F under a current density of 50 mA cm^-2 and electrolysis time of 3 hours. The treatment achieved a removal efficiency of 79% of COD with a final concentration of 80 mg L^-1 allowing the obtention of TWW which fits with the norm of reuse in irrigation with respect to the organic and nitrogenous compounds. It is worth to note that although that the pretreated effluent with CF achieved a lowest electric energy consumption compared to the EO only with 122.73 kWh.Kg COD⁻¹. A neutralization post-treatment is needed in this case.

Keywords: poultry slaughterhouse wastewater, Coagultion/Focculation process, electrochemical oxidation/reduction, BDD electrodes, reuse.

Audience Take-Away:

• The performance of the AOP namely the EO with bipolar Si/BDD cell for the treatment of the raw PSWW permits to produce water for irrigation.
• The performance of the combined system EO/CF for the treatment of PSWW les to decrease energy consumption.
• Insights related to the integration of the AOP treatment in the agri-food industry for reuse purpose.
• Alternative treatment instead the biological treatment usually in the agri-food industry
• The evaluation of the treatment performance and the introduction of reuse indicator in the evaluation of treatment performance in water scarcity context.
• The determination of the EO treatment performance alone or combined to C/F under different current densities will help to estimate the optimal operating conditions.
• The evaluation of the treatment energy consumption which will help in the design of innovative sustainable treatment in agrifood sector
• Provide non-conventional water in arid region.

Biography:

Prof.  Dr. Hanene Akrout. is researcher at CERTE since 2006, PhD on electrochemistry. She is a laboratory head and an expert on sustainable local wastewater management and the development of innovative technologies in industrial sector as well as the impact of wastewater discharge in water receptors.  She is involved in several international projects as SUSTAIN COAST, INTHEMED and AGREEMED (PRIMA programme). Prof Hanene Akrout supervised many theses dealing with the development of sustainable wastewater treatment, innovative electrode coating and biocorrosion and protection.