Fenton's Process for Post-Biologically Treated Cheese Production Wastewaters Final Remediation. Toxicity Assessment

Abstract

The use of the Fenton's process for the depuration of a post-biological treated milk whey wastewater was studied, aiming to achieve adequate operational conditions for a cost effective treatment to generate a suitable effluent to be directly discharged into the natural water courses. A design of experiments was implemented in order to understand the role of the independent parameters and their combinations over the treatment process. From our results the hydrogen peroxide concentration and the ratio between [H 2 O 2 ]:[Fe 2+ ] as well as their interaction were statistically important concerning both TOC and COD removal. The experiments performed at the highest value of [H 2 O 2 ] and at the lowest level of [H 2 O 2 ]:[Fe 2+] lead to effluents accomplishing the environmental legislation. Moreover, toxicological tests revealed that the treated effluent was harmless to the ecosystems. A cost estimation analysis was performed and the catalytic activity of the remaining sludge from the homogeneous process was checked. This activity decreases with the number of reuses which reduces the possibility of the direct utilization of the sludge.

Integration of advanced oxidation processes and activated sludge for the treatment of high refractory industrial wastewater

“…Oxidation terminates at the end of 420 min operation when NaOH was added until PH reached 11 to precipitate the iron in solution that would remove a fraction of the organic matter, promoted by the consequent coagulation step, and quench the remaining H 2 O 2 . Then, after 15 min agitation promoting iron flocks formation and total residual hydrogen peroxide depletion, specified dose of cationic flocculant was added to improve flock formation and consequent settling.…”

“…One of the advantages of these processes, besides the possible mineralization of pollutants, is the fact that they can also enhance the mixture biodegradability due to bio‐refractory contaminants oxidation . This will allow the application of a posterior biological treatment.…”

Final Remediation of Post-Biological Treated Milk Whey Wastewater by Ozone

“…In this context, in a previous work regarding the catalytic ozonation of a simulated phenolic mixture it was verified that the depuration using the catalytic system involving Mn-Ce-O 70/30 developed through surface reactions with both pollutants and ozone being adsorbed in the catalyst surface (Martins and Quinta-Ferreira, 2009b). Meanwhile, the N-150 solid catalyst promotes ozone decomposition into hydroxyl radicals reacting with the organic compounds in the liquid bulk (Martins and Quinta-Ferreira, 2010). Meanwhile, in the specific case of the present effluent, both catalysts merely acted as adsorbents.…”

“…In our previous work (Martins et al, 2010), Fenton's process was considered for the final depuration of this effluent leading to a stream suitable to be disposed into the surroundings. However, even achieving high depuration levels, this process leads to a treated wastewater not yet suitable to be discharged into the water courses since it does not accomplishes the environmental legislation.…”

Reduction of Total Phenols, Total Phosphorus and Turbidity by Uncatalytic Oxidation Processes in Cheese Whey Wastewater

“…Coagulation-flocculation with FeSO4, FeCl3 and Al2(SO4)3 [11,12], alkaline and acid precipitation with NaOH, Ca(OH)2 and H2SO4 [12][13][14][15][16] and oxidation processes with O3, O3+H2O2, O3+N-150 (Fe2O3-MnOx), O3+Mn-Ce-O (70/30) [17] and Fenton [18] have been applied. Martins and Quinta-Ferreira [17] and Martins et al [18] reported the reduction of organic matter by oxidation processes in pretreated cheese whey wastewater. However, no study reports the reduction of total phenols, total phosphorus and turbidity by oxidation processes in raw cheese whey wastewater.…”