Treatment of Winery Wastewater by Combined Almond Skin Coagulant and Sulfate Radicals: Assessment of HSO5− Activators

Abstract

The large production of wine and almonds leads to the generation of sub-products, such as winery wastewater (WW) and almond skin. WW is characterized by its high content of recalcitrant organic matter (biodegradability index < 0.30). Therefore, the aim of this work was to (1) apply the coagulation–flocculation–decantation (CFD) process with an organic coagulant based on almond skin extract (ASE), (2) treat the organic recalcitrant matter through sulfate radical advanced oxidation processes (SR-AOPs) and (3) evaluate the efficiency of combined CFD with UV-A, UV-C and ultrasound (US) reactors. The CFD process was applied with variation in the ASE concentration vs. pH, with results showing a chemical oxygen demand (COD) removal of 61.2% (0.5 g/L ASE, pH = 3.0). After CFD, the germination index (GI) of cucumber and corn seeds was ≥80%; thus, the sludge can be recycled as fertilizer. The SR-AOP initial conditions were achieved by the application of a Box–Behnken response surface methodology, which described the relationship between three independent variables (peroxymonosulfate (PMS) concentration, cobalt (Co2+) concentration and UV-A radiation intensity). Afterwards, the SR-AOPs were optimized by varying the pH, temperature, catalyst type and reagent addition manner. With the application of CFD as a pre-treatment followed by SR-AOP under optimal conditions (pH = 6.0, [PMS] = 5.88 mM, [Co2+] = 5 mM, T = 343 K, reaction time 240 min), the COD removal increased to 85.9, 82.6 and 80.2%, respectively, for UV-A, UV-C and US reactors. All treated wastewater met the Portuguese legislation for discharge in a municipal sewage network (COD ≤ 1000 mg O2/L). As a final remark, the combination of CFD with SR-AOPs is a sustainable, safe and clean strategy for WW treatment and subproduct valorization.

Sulfate Radical Advanced Oxidation Processes: Activation Methods and Application to Industrial Wastewater Treatment

“…It shows the operational conditions and the attained efficiencies. In Jorge et al [20], PMS was activated by cobalt ions in a UV-A LED reactor, for the treatment of WW. The conditions were revealed to be effective for sulfate radical activation, with 82.3% COD removal.…”

Treatment of Swine Wastewater Using Almond and Cherry By-Products as Coagulants

“…The coagulation-flocculation (CF) process was performed in a Jar-test device (ISCO JF-4, Louisville, KY, USA), with four mechanical agitators powered by a regulated speed engine. Each coagulant was mixed with the samples of SW with a fast mix of 150 rpm/3 min and a slow mix of 20 rpm/20 min, at ambient temperature (25 • C), as described previously [4]. To optimize the CF process, different levels of pH (3.0, 6.0, natural and 9.0) and coagulant concentrations (0.1, 0.5, 1.0 and 2.0 g/L) were tested.…”

“…Moreover, the turbidity and TSS removal effectiveness slightly reduced as the pH value increased. Previous studies using plant-based coagulants reported that the negatively charged wastewater at lower pH may accelerate the adsorption process of the particles into protein-contained coagulants, increasing the turbidity and TSS removal [4,10]. Therefore, pH 3.0 was chosen to test different concentrations of coagulant.…”

“…However, their implementation in industries leads to additional costs. Therefore, the combination of AOPs with other wastewater treatments should be considered to optimize the cost-effectiveness of the treatment process [4]. The coagulation-flocculation (CF) process is used to remove organic and inorganic substances and colloidal particles during wastewater treatment.…”

Olive Washing Wastewater Treatment by Coagulation/Flocculation/Decantation and UV-A LEDs/Fenton

“…The combination of the CFD with AOPs, which are considered promising alternatives to degrading-or, at least, the turning into more biodegradable compounds of-recalcitrant organic matter through the generation of hydroxyl radicals (HO • ) [5]. These radicals have high oxidation potential; they are nonselective species, interacting with the pollutants and oxidizing them to CO 2 , H 2 O, and partly oxidized species [6].…”