Treatment of Olive Oil Mill Wastewater by UV-Light and UV/H2O2 System

Abstract

Olive oil mills generates large volumes of wastewaters (OMW). The absence of legislation, which manages and obligates the treatment of OMW has led to the creation of large build-evaporation ponds as a solution for this environmental problem. The function of these ponds is the evaporation of wastewater during summer months. However, evaporation isn't enough to eliminate all wastewater in the rafts and this fact allows the generation of a great volume of concentrate wastewater with high organic load (COD = 0.5-38 g O2/L). The environmental impact produced by the accumulation of polluted wastewater demands the design of processes for OMW treatment. In this sense, the influence of ultraviolet light (UV) and the combined system of UV/H2O2, in the degradation of organic matter of OMW, were studied. UV-light application at a short time (<30 min) implies a removal values in COD = 15-22%, total carbon (TC), total organic carbon (TOC) and total nitrogen (TN) in the range 34% to 43%. The turbidity elimination was registered in the range 68% to 70%. In the case of combined UV/H2O2 system the removal percentages were 40-48% for COD, 39.4-51.9% for TC, 33.0-48.0% for TOC, 37.0-53.1% for TN, and 66.8-93.4% for turbidity.

Study of Catalysts’ Influence on Photocatalysis/Photodegradation of Olive Oil Mill Wastewater. Determination of the Optimum Working Conditions

“…In this sense, and in order to define the effect of the combination or not among UV light, oxidant and catalyst in the same system, it could be indicated that the removal percentages were increased according to the following sequence UV < UV/H 2 O 2 < UV/FeCl 3 /H 2 O 2 . The final percentages reached for the parameters TC, TOC and TN have been for only UV-light 43.3%, 34.3% and 40.0%, for UV/H 2 O 2 system 42.9%, 38.4% and 45.3% [5] and for the system UV/FeCl 3 /H 2 O 2 , 71.8%, 57.9% and 67.9%, respectively. These resulted were obtained using OMW with similar initial TOC value = 3929 mg/L.…”

“…In this sense, when only photolysis (UV-light) was applied ( Figure 1B), the initial organic load is independent of the final removal percentages registered. In addition, Hodaifa et al [5] developed photo-oxidation of OMW using UV/H 2 O 2 system at similar conditions to that used in this work but without a catalyst (initial COD = 1944.2 mg O 2 /L, initial H 2 O 2 concentration = 10% (w/v), stirring speed = 150 rpm, T = 20 • C and pH = 3). In this sense, and in order to define the effect of the combination or not among UV light, oxidant and catalyst in the same system, it could be indicated that the removal percentages were increased according to the following sequence UV < UV/H 2 O 2 < UV/FeCl 3 /H 2 O 2 .…”

“…Figure 6 shows the variation of TOC conversion values of OMW throughout the photodegradation reaction time for the best initial concentration of the hydrogen peroxide (7.5%, w/v) and for other H 2 O 2 concentration (5%, w/v). In previous work [5], it has been demonstrated the effective adjustment of TOC conversion data to the integrated equation of the Lagergren model [51],…”

“…For the press and three-phase continuous centrifugation processes, chemical oxygen demand (COD) and biological oxygen demand (BOD 5 ) values of wastewater vary in the range of 40-220 g O 2 /L and 35-110 g O 2 /L, respectively [2,3]. Nevertheless, for the two-phase continuous centrifugation process, the COD and BOD 5 values of wastewater vary from 0.5 to 65 g O 2 /L and 0.5 to 19 g O 2 /L, respectively [4][5][6]. In general, total phenolic compounds (TPCs) are in the range of 0.044-1 g/L [7,8].…”

A Competitive Study Using UV and Ozone with H2O2 in Treatment of Oily Wastewater

“…(14) studied the use of UV, H2O2 /UV and ozone in treatment of pharmaceuticals wastewater and they found that ozonation was the most effective process among the three tested processes. (15) (16). Their results showed that COD and TOC removal using UV were 22 and 34% respectively, while they were 48% for both COD and TOC when using UV / H 2 O 2 .…”