Treatment of cheese whey wastewater by combined electrochemical processes

Abstract

This study shows the good performance of a sequential electrochemical methodology, consisting in electrocoagulation (EC) followed by an electrochemical advanced oxidation process (EAOP), to treat raw cheese whey wastewater at laboratory and pre-pilot scales. In EC, different electrode materials like Fe, Al and stainless steel (AISI 304 and ASI 316L) were tested. Among EAOPs, photoelectro-Fenton (PEF) and electrochemical oxidation (EO) with active anodes like Pt or DSA ® and non-active ones like boron-doped diamond (BDD) were studied. At both scales, the optimum anode/cathode combination in EC was Fe/AISI 304, which yielded the highest total organic carbon (TOC) removal of 22.0-27.0%. This is due to various effects on organic compounds: (i) coagulation promoted by Fe(OH) 3 flocs, (ii) cathodic reduction, and (iii) oxidation with generated active chlorine. At small scale, the resulting wastewater was further treated by PEF at pH 3.0. The highest TOC removal was achieved using the BDD, owing to the great oxidation power of hydroxyl radicals. In contrast, total nitrogen was abated much more rapidly with active anodes because of the attack of active chlorine on N-compounds. At pre-pilot scale, the post-treatment of conditioned wastewater made by EO with a BDD/Pt flow cell combined with UVA irradiation yielded the highest TOC removal, i.e., 49.1%. The high energy consumed by the UVA lamp would be a drawback at industrial scale, which could be overcome by using sunlight.

Electrochemical Recovery of Phosphorus from Acidic Cheese Wastewater: Feasibility, Quality of Products, and Comparison with Chemical Precipitation

“…The difference between the chemical process and the electrochemical process points out that the main COD removal pathway is probably not the coprecipitation of organics with calcium phosphate. The likely COD removal mechanism in the electrochemical process is the anode-mediated formation of chlorine and associated reactive chlorine species like hypochlorite, which results in the reduction of COD. , However, it is worth mentioning that toxic chlorinated organic byproducts may be formed . After being processed for electrochemical phosphate recovery, the treated cheese wastewater will be diluted >100-fold with other industrial wastewaters.…”

“… 18 A combined electrocoagulation and electrochemical oxidation process was also suggested for the treatment of dairy wastewater. 19 In particular, it was found that electrochemical treatment can result in the disinfection of dairy wastewater, along with the removal of organic loads. 20 …”

Is dairy wastewater safe for production of edible microbial biomass: A case study of Saras dairy plant at Jaipur, India

“…Many microorganisms utilize derivatives of nitrogen both organic and inorganic to achieve optimal growth (Grunertet al, 2016).Lower values of TKN was recorded compared to previous studies (Bohnenstengelet al, 1999;Kraal et al, 2009). This could be attributed Remarkably, cheese whey water contains higher amount of total nitrogen compared to dairy wastewater (Tirado et al, 2018). Notably, high level of NOx causes toxicity in human if ingested in large quantity (Craunet al, 1981;Jaffe, 1981).…”

Is dairy wastewater safe for production of edible microbial biomass: A case study of Saras Dairy plant at Jaipur, India

“…This could be attributed to low discharge of whey into the wastewater. Britzet al 2006 Remarkably, cheese whey water contains higher amount of total nitrogen compared to dairy wastewater (Tirado et al, 2018). Notably, high level of NOx causes toxicity in human if ingested in large quantity (Craunet al, 1981;Jaffe, 1981).…”