Treatment Of Olive Mill Wastewater Research Articles

Integration of catalytic wet peroxidation and membrane distillation processes for olive mill wastewater treatment and water recovery

The degradation of organic matter present in olive mill wastewater (OMW) and the recovery of water were studied by the integration of catalytic wet peroxidation (CWPO) and direct contact membrane distillation (DCMD) for the first time. The oxidation step was performed in a fixed–bed reactor (FBR) working in continuous mode (pH0 = 4.0 ± 0.2, 60 °C, Q = 0.75 mL/min, [H2O2]/[COD]feed = 2.3 ± 0.1 gH2O2/gO2). Samples of OMW diluted by 5–and 7.5–fold were used (OMW–5× and OMW–7.5×, respectively), corresponding to inlet chemical oxygen demand (COD) values of 3562 ± 68 and 2335 ± 54 mg/L, total phenolic content (TPh)of177 ± 17 and 143 ± 7 mgGAeq/L, and total organic carbon (TOC) of 1258 ± 63 and 842 ± 45 mg/L, respectively. The FBR was loaded with 2.0 g of a Fe–activated carbon derived–catalyst, prepared by using olive stones as the precursor, in line with a circular economy model approach. The catalyst was selected based on the activity and stability towards polyphenolic synthetic solutions shown in previous works of the team, while actual OMW samples were used in this work. CWPO–treated samples of OMW allowed the operation of the DCMD unit at higher fluxes than with the analogous untreated ones, also showing higher rejections of organic matter from the feed solution upon DCMD, highlighting the beneficial effect of this novel configuration. Using a pre-treated sample of OMW–7.5× as feed solution (Q = 100 mL/min, Tpermeate≈18 °C, Tfeed≈66 °C), the produced permeate water stream presented several parameters well–below the legislated thresholds required for direct discharge for crops irrigation, including total suspended solids (TSS < 10 mg/L), TPh (<0.01 mgGAeq/L), biochemical oxygen demand (BOD5 < 40 mg/L), and dissolved Fe (<0.06 mg/L). Moreover, the resulting concentrated OMW–retentate streams could be recirculated to the FBR and maintain the same removal efficiencies obtained previously, despite the increased initial organic loadings of the retentate after DCMD.

Abstract 4044: An extract of olive oil wastewater enhances chemotherapy effects on breast cancer cells without exacerbating cardiovascular toxicity

Abstract Background: In cancer patients receiving chemotherapeutic agents, cardiovascular toxicities still remains one of the most undesirable side effects. One of the best known cardiotoxic agents is doxorubicin, a very powerful chemotherapeutic molecules for breast cancer. Extra-virgin olive oil (EVOO) is rich in cancer preventive polyphenols endowed with anti-inflammatory, anti-oxidant activities which could exert protective effects on heart cells. A very interesting derivative of EVOO preparation is represented by purified extracts from olive mill waste waters (OMWW) rich in polyphenols. Here, we have investigated the anti-cancer activity of a OMWW preparation, named A009, on breast cancer cells when combined with chemotherapeutics, as well as its potential cardioprotective activities. We had previously reported additive effects with cisplatin in prostate cancer cells. In previous studies we have shown that the combination of A009 with cisplatin or 5-FU was effective in decreasing prostate and colon cancer cell growth, while it did not further reduce growth of rat cardiomyocytes also treated with cisplatin or 5-FU. Here we used 5-fluorouracil as comparison. Methods: Combination of A009 and chemotherapy was investigated in vitro on human breast cancer cell lines BT459, MDA-MB-234. The cardioprotective effects of the A009 extract were tested on H9C2 (cardiomyocytes) cells co-exposed to doxorubicin or 5-fluorouracil and in zebrafish embryos. Results: Adding A009 to doxorubicin or 5-FU was effective in decreasing breast cancer cell growth in monolayer. Breast tumor spheroids morphologically appeared less stable and with reduced diameter when treated with A009 extracts and with the chemotherapeutic agents 5-FU or Doxo, additive effects were observed. A009 mitigated toxicity of doxorubicin or 5-FU on rat cardiomyocytes cells H9C2. Cardioprotective effects were observed by the combination of OMWW extracts with Doxorubicin in Zebrafish embryos. In human cardiomyocytes, we observed 5-FU induced upregulation of the proinflammatory IL6 mRNA, which was reduced by OMWW treatment. Conclusions: Our study demonstrates that the polyphenol rich purified A009 extracts enhance the effect of chemotherapy of doxorubicin and 5-FU on breast cancer cells but mitigates chemotherapy adverse effects on heart in vivo and on cardiomyocytes, appearing as a potential cardio-oncological prevenzion agent. Citation Format: Adriana Albini, Marco M. Festa, Denisa Baci, Nadia Benedetto, Karolina Gutmanska, Nicoletta Macrì, Giovanna Finzi, Fausto Sessa, Serena Zacchigna, Antonino Bruno, Douglas M. Noonan. An extract of olive oil wastewater enhances chemotherapy effects on breast cancer cells without exacerbating cardiovascular toxicity [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 4044.

Studies on the activated sludge process crucial parameters controlling olive mill wastewater treatment

Olive mill wastewater (OMW) represents a severe environmental problem for Mediterranean producer countries. The release of OMW, in urban areas, in public sewerage system constitute a serious problem for wastewater treatment plant (WWTP) based on biological processes. This study delivers a critical and a comprehensive analysis on activated sludge biomass and process crucial parameters involved in the treatment of OMW. Principal component analysis (PCA) has been applied to master the relationship between activated sludge physiological state and process performances stability. After the acclimation step with easily biodegradable synthetic substrate (SS), increased OMW F/M mass ratio has been applied to the bioreactor (60 L) of experimental pilot-scale AS system in respect to its nominal capacity. PCA highlight two main periods, a first stressful period presented by G1[T0–T10%], G2[T20%–T30%] and G3[T40%–T50%] AS microbial communities were very sensitive to substrate changes. This was manifested by low metabolic activity (OUR, SOUR and SOURinh), important drop in AS microbial communities content, an increase in soluble microbial products (SMP), a fluctuate performances in COD and total phenols abatements as well as in flocks settleability (SVI). Afterwards, a reestablishment second period presented by G4[T60%–T100%] of key process parameters and AS biomass efficiency indices is reached. This period characterized by the substantial content, resistance and adaption of AS microbial communities to OMW as F/M. Succeeding optimal AS biomass and process performances, under stressful conditions, requires a precise knowledge and control of decisive parameters involved in OMW treatment and this study could be an efficient practical approach in case of OMW also for further toxic compounds.

Removal of COD, phenol, and colour from olive mill wastewater by iron-activated persulphate process: multivariate optimisation approach

ABSTRACT In this study, the treatability of olive mill wastewater by iron-activated persulphate (PS) oxidation was investigated. Central Composite Design (CCD) was applied to optimise the process parameters and establish a mathematical model for total phenol, chemical oxygen demand (COD), and colour removal from olive mill wastewater. The effect of process variables (PS dose, Fe2+ dose, initial pH, and reaction time) on pollutant removal efficiency was evaluated. The correlation coefficients of the quadratic polynomial equations were high for COD, total phenol, and colour removal by PS oxidation, and the model was found to be applicable. Optimum conditions determined by the developed model for maximum COD removal were pH 5, PS dose 206.7 mM, Fe2+ dose 70 mM, and reaction time 95 min. The COD, total phenol, and colour removal efficiencies estimated by the applied model were 46.74%, 94.62%, and 96.04%, respectively. The removal efficiencies obtained under optimum conditions as a result of the validation experiments were 45.5%, 93.8%, and 95.5% for COD, total phenol, and colour removal, respectively. The results of the study showed that PS oxidation in which Fe2+ is used as an activator is a suitable alternative for olive mill wastewater treatment.

Comparing the performance of UV/Acetylacetone and UV/O3 processes for treatment of olive mill wastewater

Background: Olive mill wastewater (OMW) is characterized by its high organic content and refractory compounds. The aim of this study was to evaluate and compare the efficiency of UV/O3 and UV/ acetylacetone (UV/AcAc) processes for treatment of pretreated OMW by coagulation/microfiltration (C&amp;M) process. Methods: In this study, a laboratory-scale UV plug flow reactor with ancillary equipment was fabricated. The experimental factors including initial pH (5-9), O3 dosages (1.5-4.5 g/h), and AcAc concentrations (0.01-0.03 M) were measured. For both processes, a reaction time of 120 min was considered. The effect of these variables on removal of wastewater contaminants including BOD, COD, TSS, turbidity, phenol, oil, and grease were investigated. Results: Results showed that raw OMW has a high load of pollutants and very low biodegradability (BOD5 /COD=0.12). In UV/O3 process, the optimal conditions were obtained at pH 8 and ozone injection at 4 g/h. The combined C&amp;M-UV/O3 process removed 78.75% COD, 46.66% BOD5 , 90.88% total phenol, 91.78% TSS, 99.14% oil and grease, and 98.38% turbidity, with promotion of BOD5 / COD from 0.12 to 0.33. In UV/AcAc process, the optimal conditions were achieved at pH 5 and AcAc concentration of 0.03 M. The combined C&amp;M-UV/AcAc process removed 58.75% COD, 67.58% BOD5 , 38.03% total phenol, 83.50% TSS, 93.65% oil and grease, and 95.00% turbidity, with promotion of BOD5 / COD from 0.12 to 0.22. Conclusion: The results showed that the UV/O3 process is completely superior to the UV/AcAc process for removal of OMW contaminants, as well as promoting the biodegradability of OMW.

An Olive Oil Mill Wastewater Extract Improves Chemotherapeutic Activity Against Breast Cancer Cells While Protecting From Cardiotoxicity.

Cardiovascular toxicity in cancer patients receiving chemotherapy remains one of the most undesirable side effects, limiting the choice of the most efficient therapeutic regimen, including combinations of different anticancer agents. Anthracyclines (doxorubicin) and antimetabolites (5-fluorouracil (5-FU), capecitabine) are among the most known agents used in breast cancer and other neoplasms and are associated with cardiotoxic effects. Extra-virgin olive oil (EVOO) is rich in polyphenols endowed with antioxidant cardioprotective activities. Olive mill wastewater (OMWW), a waste product generated by EVOO processing, has been reported to be enriched in polyphenols. In this study, we investigated the activities of polyphenol-rich extract from OMWW, A009, in cooperation with chemotherapy on two breast cancer cell lines, namely, BT459 and MDA-MB-231, in a cardio-oncology perspective. The effects of A009 on cardiac cells were also investigated with and without chemotherapeutic agents. Cell viability was determined on BT459 and MDA-MB-231 (i.e., breast cancer cells) and H9C2 (i.e., rat cardiomyocytes) cells, using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. A spheroids assay was used as a 3D in vitro model on BT459 and MDA-MB-231 cells. For in vivo studies, the murine sponge assay of angiogenesis was used as a model of breast cancer-associated vascularization. The embryo of Danio rerio (zebrafish) was used to detect the cardioprotective activities of the OMWW. We found that the A009 extract exhibited antiangiogenic activities induced by breast cancer cell supernatants and increased T-cell recruitment in vivo. The combination of the OMWW extracts with doxorubicin or 5-FU limited BT459 and MDA-MB-231 cell viability and the diameter of 3D spheroids, while mitigating their toxic effects on the rat H9C2 cardiomyocytes. Cardioprotective effects were observed by the combination of OMWW extracts with doxorubicin in zebrafish embryos. Finally, in human cardio myocytes, we observed 5-FU-induced upregulation of the inflammatory, senescence-associated cytokine IL6 and p16 genes, which expression was reduced by OMWW treatment. Our study demonstrates that the polyphenol-rich purified OMWW extract A009 combined with cancer chemotherapy could represent a potential candidate for cardiovascular protection in breast cancer patients, while increasing the effects of breast cancer chemotherapy.

Sustainable and Eco-Friendly Conversions of Olive Mill Wastewater-Based Media by Pleurotus pulmonarius Cultures

Pleurotus pulmonarius mushroom was cultivated on liquid cultures with olive mill wastewaters (OMWs) of initial phenolic compound concentrations of 0 (control), 1, 2 and 3 g/L and glucose at initial concentrations of 40 and 60 g/L. The ability of the fungus to grow on media containing toxic compounds enriched with glucose was assessed through biomass production, glucose consumption, polysaccharide (IPS) accumulation and total cellular lipids biosynthesis, while the total phenolic compounds (TPC) and antioxidant component monitoring were also assessed during a 43-day fermentation. An analysis of the total simple sugar composition of IPS and the total fatty acid composition of lipids was performed. The phenolic reduction and media decolorization were also monitored. Results showed that the addition of glucose in OMW-based media had a positive effect on biomass, IPS and lipid production and increased the unsaturated fatty acids and TPC concentration. The maximum recorded values were the following: biomass 32.76 g/L, IPS 4.38 g/L (14.70%, w/w in dry weight), lipids 2.85 g/L (11.69%, w/w in dry weight). The mycelial lipids were unsaturated and dominated by linoleic acid, whereas IPS were composed mainly of glucose. Significant phenolic compound reduction (87–95%) and color removal (70–85%) occurred. Results strongly suggest the potentiality of P. pulmonarius utilization in the OMW treatment.

Evaluation of the Activation Procedure on Oxone Efficiency for Synthetic Olive Mill Wastewater Treatment

Wastewater from the olive oil industry is an environmental problem which is growing in the Mediterranean region. Presence of phenolic compounds and high organic matter load are characteristics of this effluent that make it difficult to treat. In this study, the applicability of sulfate radical based advanced oxidation processes (SRbAOPs), using peroxymonosulfate (PMS) as oxidant, was evaluated in the treatment of synthetic olive mill wastewater (OMW). Different procedures for PMS activation were studied such as activation by Fe(II), radiation (visible and UV-A) and ultrasounds. The operation conditions were optimized by testing pH values, Fe(II) and PMS loads. At optimal conditions ([PMS] = 1600 mg/L, [Fe2+] = 700 mg/L and pH = 5) 60 ± 2% COD removal was achieved. This process shows to be selective since complete degradation of 3,4,5-trimetoxybenzoic acid was obtained after 3 min of reaction. The addition of light, PMS/LED/Fe(II) and PMS/UV-A/Fe(II), did not increase the efficiency of organic matter removal, with 56 ± 2% and 58 ± 1% of COD removal, respectively, comparatively to PMS/Fe(II) (60 ± 2%). PMS activated by ultrasounds led to 52 ± 3% and 23 ± 2% removal of phenolic compounds and COD, respectively, after 60 min. Toxicity tests using Lepidium sativum showed that treatment with PMS/UV-A led to a treated sample with mild inhibition of plant growth.

Sustainable iron-olive stone-based catalysts for Fenton-like olive mill wastewater treatment: Development and performance assessment in continuous fixed-bed reactor operation

Iron oxide catalysts supported on activated carbon prepared from olive stones (OSAC–Fe) were used for the catalytic wet peroxide oxidation of refractory polyphenolic solutions and real olive mill wastewater (OMW) in a fixed-bed reactor (FBR). Catalysts were prepared with different precursors and Fe-loadings. The resulting catalysts were essentially microporous materials with well-developed surface areas (SBET = 588–689 m2/g), whereas the nature and distribution of metallic nanoparticles were found to be strongly dependent on the precursor used.The stability and catalytic performance were screened in a batch reactor using a synthetic solution and the most promising catalyst – prepared at 5 wt.% Fe using Fe(NO3)3 as the precursor – was selected for the operation of a continuous FBR. Different operational conditions were evaluated through a parametric study. At 60 °C, [H2O2]feed = 1.5 g/L and Q = 0.75 mL/min, 87% total phenolic content removal (TPh), 28% mineralization and 88% H2O2 conversion were achieved at steady-state. Real OMW samples were then treated at a fixed [H2O2]/[COD] in the feed, and TPh removals of 57–71% and COD (chemical oxygen demand) reductions of 26–34% were attained. The resulting effluents showed an overall reduction of eco-toxicity and improvement of biodegradability indices.

Treatment of olive mill wastewaters using infiltration/percolation system: effect on microbial communities in the soil filter

Treatment of olive mill wastewaters using infiltration/percolation system: effect on microbial communities in the soil filter

Olive oil mill wastewater treatment by a combined process of freezing, sweating and thawing

Olive oil mill wastewater treatment by a combined process of freezing, sweating and thawing

Integration of Catalytic Wet Peroxidation and Membrane Distillation Processes for Olive Mill Wastewater Treatment and Water Recovery

Integration of Catalytic Wet Peroxidation and Membrane Distillation Processes for Olive Mill Wastewater Treatment and Water Recovery

Coupling coagulation-flocculation to volcanic tuff-magnetite nanoparticles adsorption for olive mill wastewater treatment

A combined coagulation-flocculation/adsorption approach has been developed to remove organic and phenolic compounds from Olive mill wastewater (OMW). The effect of utilizing coagulation-flocculation on the removal of total suspended solids (TSS) prior to volcanic tuff (VT) /magnetite nanoparticles (MNPs) adsorption was investigated. On the other hand, the influence of VT activation either by calcination or by acid/base treatment followed by calcination was established. Moreover, the adsorption capabilities of activated and non-activated VT coupled with magnetite nanoparticles were evaluated for chemical oxygen demand (COD) and total phenolic content (TPC) removal via batch and column approaches. The coagulation-flocculation processes were successfully reduced the TSS, COD, and TPC by 99%, 48% and 44%, respectively. The removal efficiency of VT for COD was increased by acid activation followed by calcination. Further enhancement was achieved by coupling with 0.5% by weight of magnetite nanoparticles with maximum COD removal of 76% at pH 8. Instead, VT activated by calcination and coupled with 0.5% by weight magnetite nanoparticles at pH 10 provided good removal for both TPC and COD of 73% and 70%, respectively. Overall, the results of this research reveal that the combined coagulation-flocculation/adsorption processes can enhance the removal of organic contaminants from OMW. This study has the potential to be considered as an efficient treatment approach for the local and worldwide olive mill industry.

A novel bioprocess combining anaerobic co-digestion followed by ultra-filtration and microalgae culture for optimal olive mill wastewater treatment

Treatment of olive mill wastewater (OMW) has received considerable research globally due to its influence on the technical, economic, and environmental sustainability of wastewater biogas production. This work presents a novel combined biological process for OMW treatment in terms to produce for the first time, treated OMW and a valuable microalgae biomass. The process involves anaerobic co-digestion (AD), a low cut-off membrane ultra-filtration (UF) and a subsequent Scenedesmus sp. culture. The AD of OMW was conducted at high initial COD ranging from 28 to 38 g/L using an up-flow anaerobic fixed bed bio-reactor (300 L). Results revealed that the maximum biogas production was about 0.507 L/g CODintroduced.day containing 73% of methane corresponding to a methane yield of 0.370 L/g CODintroduced.day obtained at an organic loading rate of 4.58 g COD/L.day. High removal levels of COD, total phenolic compounds, and total suspended solids in the anaerobic liquid digestate (ALD) were achieved after AD and UF. Scenedesmus sp. was then cultivated on the ultra-filtrated ALD. A maximum biomass productivity of 0.15 g/L.day was recorded when Scenedesmus sp. is grown on 25% of ultra-filtrated ALD with a maximum nitrogen removal rate of 15.18 mg/L.day and an almost total elimination of phosphorus and phenolic compounds.

Fe3+- IDS as a new green catalyst for water treatment by photo-Fenton process at neutral pH

In this work, a new green and fully biodegradable (96% after 28 days) catalyst, Fe3+-iminodisuccinate complex (Fe-IDS), was prepared, characterized and applied in Fenton processes (dark and photo-Fenton) for water treatment, using phenol as model organic pollutant. Experiments were performed both in dark and under solar/UV-C radiation to evaluate the effect of the light source and [H2O2] (fixed at 5.3 mM)/[Fe-IDS] ratio on the catalytic degradation of phenol (50 mg L−1). Subsequently, photo-Fenton IDS supported process was compared to other advanced oxidation processes (AOPs) (namely, conventional Fenton at pH 3 and H2O2 photolysis, under solar and UV-C irradiation, respectively). The best results (54% and 49% COD removals for solar and UV-C based processes, respectively) were obtained using a [H2O2]/[Fe-IDS] molar ratio of 250 (R250), corresponding to 0.021 mM of Fe-IDS followed by R500 (0.01 mM of Fe-IDS) and R150 (0.035 mM of Fe-IDS). Process efficiency was in the order solar/Fe-IDS/H2O2 >UV-C/Fe-IDS/H2O2 >Fe-IDS/H2O2 (k = −0.0114, −0.0073 and −0.0018 min−1 respectively) for R250. A complete removal of phenol in terms of COD was obtained for solar/Fe-IDS/H2O2 and UV-C/Fe-IDS/H2O2. Furthermore, the application of Fe-IDS complex for real industrial (olive oil mill) wastewater treatment was also investigated (initial COD in diluted sample 2.4 g L−1). At constant H2O2 concentration (58.82mM), the best performance in terms of COD removal (55%, k = 0.0031 min−1) and biodegradability (BOD5/COD increased from 0.16 to 0.45) was obtained for the condition R150 (0.37 mM of Fe-IDS). Fe-IDS allows to overcome the main limitation (acidic pH) of conventional (photo)Fenton process, making the IDS supported (photo)Fenton an attractive option for water and wastewater treatment in a wide pH range.

Olive mill wastewater phytoremediation employing economically important woody plants

In this study two plant species, Punica granatum L. and Myrtus communis L., have been tested as candidates for phytoremediation of olive mill wastewater (OMW) through recirculation in soil pilot units, according to the proposed patented technology by Santori and Cicalini [EP1216963 A. 26 Jun 2002]. Wastewater was treated in batches of low to high organics strength (COD: 2 700–45 700 mg/L) during summer months of two consecutive years. Dynamics of the most important wastewater parameters were investigated, and corresponding removal rates were estimated. During treatment of low organic load OMW, average removal rate of organics, phenolics, total nitrogen and total phosphorus were 0.68 g-COD/kg-soil d, 0.073 g-TPh/kg-soil d, 0.033 g-TN/kg-soil d and 0.0074 g-TP/kg-soil d respectively and plants proved to be tolerant to the OMW. During treatment of high organic load OMW removal rates were roughly 10-fold higher although phytotoxic symptoms were observed. Plants were found to contribute greatly to the OMW treatment process since organics removal rates in pilot units were found to be at least 10-fold higher than in wastewater treatment in non-vegetated soil.Plant species with high added value products such as pomegranate and myrtle trees were used in this study, improving the circular economy potential of the aforementioned technology. Moreover, its efficiency has been demonstrated by quantification of the overall removal rates of key constituents as well as the contribution of the plants in the OMW treatment.

Persulfate Process Activated by Homogeneous and Heterogeneous Catalysts for Synthetic Olive Mill Wastewater Treatment

Wastewaters from the olive oil industry are a regional environmental problem. Their phenolic content provides inherent toxicity, which reduces the treatment potential of conventional biological systems. In this study, Sulfate Radical based Advanced Oxidation Processes (SRbAOPs) are compared with advanced oxidation processes (namely Fenton’s peroxidation) as a depuration alternative. Synthetic olive mill wastewaters were submitted to homogeneous and heterogeneous SRbAOPs using iron sulfate and solid catalysts (red mud and Fe-Ce-O) as the source of iron (II). The homogenous process was optimized by testing different pH values, as well as iron and persulfate loads. At the best conditions (pH 5, 300 mg/L of iron and 600 mg/L of persulfate), it was possible to achieve 39%, 63% and 37% COD, phenolic compounds and TOC removal, respectively. The catalytic potential of a waste (red mud) and a laboratory material (Fe-Ce-O) was tested using heterogenous SRbAOPs. The best performance was achieved by Fe-Ce-O, with an optimal load of 1600 mg/L. At these conditions, 27%, 55% and 5% COD, phenolic compounds and TOC removal were obtained, respectively. Toxicity tests on A. fischeri and L. sativum showed no improvements in toxicity from the treated solutions when compared with the original one. Thus, SRbAOPs use a suitable technology for synthetic OMW.

Co-composting of cotton residues with olive mill wastewater: process monitoring and evaluation of the diversity of culturable microbial populations

With the aim to recommend an integrated alternative for the combined treatment of olive mill wastewater (OMW) and cotton residues (CR), and the production of high value and environmentally friendly products, two compost piles were set up. The first pile (control, pile 1) consisted of ginned CR, whereas the second (pile 2) was made of CR with the addition of OMW. A series of physicochemical parameters and the culturable microbial diversity in both piles were assessed. Co-composting (pile 2) displayed higher temperatures during the whole process, a prolonged second thermophilic phase and temperature values higher than 40°C even after the thermophilic stage. Comparing the physicochemical parameters of the pile 2 with those of the pile 1, it was deduced that pH in the former was more acidic during the onset of the process; the EC values were higher throughout the process, while the levels of ammonium and nitrate nitrogen, as well as the NH4+/NO3- ratios, were lower at most of the sampling dates. By evaluating the abovementioned results, it was estimated that the co-composting process headed sooner toward stability and maturity, Isolated microorganisms from both piles were identified as members of the genera Brevibacillus, Serratia, Klebsiella, and Aspergillus, whereas active thermotolerant diazotrophs were detected in both piles at the 2nd thermophilic phase emerging a promising prospect upon further evaluation for enhancing the end-product quality. Our findings indicate that co-composting is an interesting approach for the exploitation of large quantities of agro-industrial residues with a final product suitable for improving soil fertility and health.

Treatment of olive mill wastewater by adsorption of phenolic compounds

Treatment of olive mill wastewater by adsorption of phenolic compounds

Impact of ultrasonic pretreatment on Fenton-based oxidation of olive mill wastewater - towards a sustainable treatment scheme

This study evaluated the potential of ultrasonic enhanced Fenton-based advanced oxidation to reduce toxicity, total phenol (TPh) and organic matter (COD) from olive mill wastewater (OMW). Emphasis was also placed on suggesting a sustainable treatment strategy in the light of accumulated scientific evidence, indicating the role of Fenton-based oxidation in the suggested scheme. Fenton oxidation and Fenton-like oxidation (with Fe2+ and Fe3+) were tested as selected advanced oxidation methods. The experiments were conducted in such a way that the individual removal efficiencies of ultrasonication and advanced oxidation processes be evaluated separately and in sequence. The impact on toxicity removal was tested by means of a standard respirometric method, also currently used to assess biodegradation in wastewaters. Response Surface Methodology (RSM) involving central composite design (CCD) was implemented to assess the optimum conditions. Results highlighted the merit of Fenton-based oxidation with an 80% TPh reduction and a decrease of toxicity down to the narrow margin of 13–17%, together with a COD reduction of 20–26%, all quite meaningful for the following step of biological treatment. The ultrasonic pretreatment also proved to be quite useful as it secured up to 40% of particulate COD dissolution. Studies on particle size distribution of the OMW clearly showed that preliminary treatment including advanced oxidation would leave behind the bulk of soluble COD accumulated below the size of 3 nm. Accordingly, co-treatment of OMW diluted with municipal sewage was recommended after a pretreatment sequence of holding/plain settling; chemical treatment and Fenton-based oxidation. For OMWs with low particulate COD (VSS) content, Fenton-based oxidation enhanced by ultrasonic pretreatment would be a viable option in the view of effective particulate COD dissolution achieved in this study when coupled with ultrafiltration, prior to joint biological treatment with sewage. The study highlighted advanced oxidation as an indispensable step in the treatment of olive mill wastewaters.