Traitement des effluents d’abattoir de viande rouge par électrocoagulation-flottation avec des électrodes en fer

Abstract

L’effluent de l’abattoir municipal de la ville de Meknès est caractérisé par une forte charge organique polluante et une coloration rouge due à la concentration élevée en sang. Les analyses physicochimiques et microbiologiques ont révélé des concentrations importantes en paramètres globaux de pollution, et une charge microbiologique marquée par la dominance des coliformes. La demande chimique en oxygène (DCO) moyenne est de 2 240 mg d’O2•L‑1. La concentration moyenne en azote total est de 290 mg•L‑1. Les orthophosphates sont à une concentration moyenne de 35 mg•L‑1. La matière extractible à l’hexane (MEH) varie entre 900 et 1 100 mg•L‑1. Les coliformes fécaux sont de 67•103 UFC•mL‑1.Le traitement par électrocoagulation-flottation utilisant des électrodes plates de fer, avec une tension électrique de 12 V et un temps de contact de 25 min, a donné de bons résultats. Il a permis l’abattement de 92,6 % de DCO, 76,2 % d’azote total, et 95,4 % des orthophosphates. Les MEH sont éliminées à 62,5 % grâce au phénomène de flottation favorisé par le dégagement des bulles d’hydrogène issues de la réduction de l’eau à la cathode, et le brassage de l’effluent par agitation dans la cellule électrolytique. Ce processus a permis également la décoloration de cet effluent, illustrée par une diminution de l'absorption à 450 nm supérieure à 90 %, et une diminution remarquable de l'absorbance UV à 254 nm, traduisant l’élimination de matière organique dissoute par des mécanismes d'oxydation électrochimiques. Les coliformes fécaux sont réduits de trois unités logarithmiques.The effluent of the municipal slaughterhouse in Meknes City, Morocco, is characterized by a high organic pollution load and red colour due to the high concentration of blood. Physicochemical and microbiological analyzes revealed significant levels of pollution and microbiological load marked by the dominance of coliform bacteria. The average chemical oxygen demand (COD) is 2,240 mg O2•L‑1. The average concentration of total nitrogen is 290 mg•L‑1 and that for orthophosphates is 35 mg•L‑1. Fat and grease content varies between 900 and 1,100 mg•L‑1. The number of fecal coliforms is 67•103 UFC•mL‑1. Treatment by electrocoagulation-flotation using iron plate electrodes, with a voltage of 12 V and a contact time of 25 min, gave good results. It can achieve reductions in chemical oxygen demand (COD) of 92.6%. Total nitrogen removal was 76.2%, and the reduction of orthophosphate was 95.4%. Fat and grease can be reduced by 62.5% thanks to the flotation step, favoured by the release of hydrogen bubbles from the reduction of water at the cathode and the mixing of the effluent by stirring in the electrolytic cell. This process also enabled the reduction of the red colour, as illustrated by the decrease in absorbance at 450 nm, a reduction exceeding 90%, and a remarkable decrease in UV absorbance at 254 nm, reflecting the removal of dissolved organic material by electrochemical oxidation mechanisms. Fecal coliforms are reduced by three logarithmic units

Optimization of nitrogen and phosphorus removal from pig slaughterhouse and packing plant wastewater through electrocoagulation in a batch reactor

“…Kabuk et al (2014) applied electrocoagulation in the Leachate treatment and obtained a removal efficiency of TKN removal efficiency of 32%. Khennoussi et al (2013), in the same paper cited above, obtained a removal of 76.2% of total nitrogen.…”

“…While studying phosphorus removal and turbidity of pork effluent with aluminum electrodes, HRT of 80 min and current density of 50 mA cm -2 , Mores et al (2016) obtained a removal of 93.6% of total phosphorus. Khennoussi et al (2013), when treating wastewater from a slaughterhouse and packing plant with electrocoagulation, applying a voltage of 12 V, 25 min contact time and iron electrodes, obtained a removal of 95.4% orthophosphate.…”

Optimization of Biogas Production from Organic Municipal Waste: Development of Activated Sludge as Digesters Inoculum

“…These waters have COD and BOD in order 2827, 1620 mg O 2 /L, respectively[52]. This is confirmed by[53] [54]. Study of Cuetos et al[49] was showed that the first 10 days, nitrogen compounds are degraded and ammonia nitrogen is released into the environment.…”

Effectiveness assessment of olive mill wastewater treatment by combined process: Natural flotation and anaerobic‐aerobic biodegradation

“…The natural flotation leads to reduce the turbidity of the OMW by 37.7%, 19.4%, 14.3%, 0.8% and 6% for samples 1, 2, 3, 4 and 5, respectively (Figure 1). Indeed, flotation is a technique used to separate solid or liquid particles from a liquid phase and which consists of bringing on the surface the materials whose density is lower, equal or very slightly higher than that of the base liquid (Khennoussi et al, 2013). Oil may be present as an undispersed surface that usually floats at the interface.…”