Valorization of olive mill wastewater through irrigation trials of Triticum durum seeds using the dilution approach

Olive mill wastewater is a by-product of olive oil extraction, characterized by a high concentration of organic matter, which presents a significant environmental challenge if not properly managed. This study was aimed at valorizing olive mill wastewater through selective fermentations to produce acetic beverages with low or no alcohol content. Olive mill wastewaters at three different dilutions (100%, 75% and 50%) were inoculated with Saccharomyces cerevisiae UMCC 855 for alcoholic fermentation. The resulting alcoholic product, with 75% olive mill wastewater, was then used as a substrate for acetic acid fermentation by Acetobacter pasteurianus UMCC 1754, employing both static and submerged acetification systems. The results showed that, at the end of the static acetification process, no residual ethanol was detected and that high concentrations of acetic and gluconic acid (46.85 and 44.87 g/L, respectively) were observed. In the submerged fermentation system, the final ethanol concentration was 24.74 g/L; the produced organic acids content reached 31.63 g/L of acetic acid and 39.90 g/L of gluconic acid. Furthermore, chemical analyses revealed that fermentation enhanced the antioxidant activity of olive mill wastewater. These results suggest promising insights for the valorization of olive mill wastewater.

Produced as a residual output of olive oil extraction, olive mill wastewater (OMW) is characterized by a high organic load and significant levels of phenolic compounds, posing notable environmental challenges. While it resists biodegradation, OMW serves as a nutrient-rich resource for microbial growth. In this study, OMW was used as renewable feedstock for microbial lipid production by oleaginous yeasts. Chemical characterization revealed that the OMW sample primarily contained 18 g/L total sugars, 3.4 g/L phenolic compounds, and high organic and mineral content of 85 and 15 g/L, respectively. Among the tested yeasts, Rhodotorula babjevaeY-SL7 stood out with a lipid accumulation yield of approximately 38% and a significant phenolic compound detoxification rate of 53.7%. To enhance lipid yield, the most effective nitrogen source was selected following preliminary evaluation, and culture conditions were then optimized using response surface methodology (RSM) based on the Box-Behnken model, incorporating three independent factors. The lipids produced from OMW showed a fatty acid composition dominated by oleic acid (69%) and palmitic acid (23%). Predictive analyses of biodiesel properties suggest this oil could be advantageous for biodiesel production. Additionally, lipid production was accompanied by carotenoid synthesis, mainly torulene (68.2%) and torularhodin (31.7%), both demonstrating significant antibacterial and antioxidant activities. The capacity of Y-SL7 to detoxify OMW and generate valuable by-products positions this approach as a promising alternative to conventional OMW treatment methods.

Treatment technologies for olive mill wastewater with impacts on plants

To assess the combination of electrocoagulation and anaerobic co-digestion of olive mill wastewaters (OMWW) with other substrates, such as chicken manure, in a continuous stirred tank reactor for biogas production. Anaerobic digestion of OMWW treated by electrocoagulation allowed higher production of biogas, up to 0.74lbiogasg-1 COD introduced compared to untreated or diluted olive mill wastewaters (OMWW) (0.37 and 0.6lbiogasg-1COD) respectively. Pretreated OMWW co-digested with chicken manure at different volumic ratios OMWW/manure in a continuous stirred tank reactor under mesophilic conditions revealed that OMWW/manure (7:3v/v) was optimal for biogas production and process stability. Anaerobic digestion could achieve promising results in depollution and valorization of OMWW under a continuous stirred tank reactor.

This research investigates an efficient dual valorization of olive mill wastewater in the biosynthesis of magnesium oxide nanoparticles and in the depollution of the effluent by Yarrowia lipolytica growth evaluation. After removal of polyphenols, the recovered biophenols were reacted with the magnesium precursor to provide magnesium oxide nanoparticles. In order to confirm the biosynthesized magnesium oxide nanoparticles, several analyses were undertaken. The Fourier transform infrared spectrum gives a broad absorption at 658 cm-1 confirming the presence of the magnesium oxide nanoparticles, while the UV/VIS absorption spectroscopy reveals an intense transition with a maximum absorption at 300 nm. The X-ray diffraction and transmission electron microscopy analyses show that nanoparticles are in pure cubic crystalline with spherical and hexagonal shapes (average size is 19.4 nm). The zeta potential analysis illustrates a negative potential proving a good stability of the biosynthesized nanoparticles. Nanoparticles were assigned for their in vitro antibacterial activity against Escherichia coli, Enterobacter aerogenes, Salmonella typhimurium, Staphylococcus cohnii, and Bacillus niacini. The evaluation of the growth of Yarrowia lipolytica on the recovered olive mill wastewater after removal of polyphenols yielded 3.2 g/L of the Yarrowia biomass in 72 h without nutriment additions, providing an important decrease of chemical oxygen demand (73 %).

The treatment of olive mill wastewater (OMW) represents still an open challenge because of its highly polluting load. One of the most affordable methods for small-medium mills is to send OMW to industrial wastewater treatment plants (IWTP). Accordingly, this work explored a strategy consisting of the biological co-treatment of real OMW and simulated urban wastewater by a moving bed biofilm reactor (MBBR), with and without (electro)Fenton pre-treatment, to simulate OMW treatment through a multi-barrier approach in an IWTP. The effluent of the MBBR without pre-treatment, despite the long period of operation of 18 months, was in compliance with the limit for total phenols (TPHs) of 0.5 mg/L only at a really low OMW's dilution ratio (DR) (1/4000 (v/v)). The Fenton oxidation (FO) and the electro-assisted Fenton (EAF) processes were investigated as pre-treatment of diluted OMW. FO resulted in good performances in terms of TPHs removal (81%) and improved biodegradability (final BOD5/COD ratio = 0.35) but in poor COD removal (24%). EAF was more effective (COD removal = 41%, TPHs removal = 85%, and final BOD5/COD ratio = 0.40) than FO. Therefore, EAF was finally investigated on undiluted OMW (COD removal = 56%, TPHs removal = 84%, and final BOD5/COD ratio = 0.62) and subsequently co-treated with simulated urban wastewater by MBBR, identifying 1/1000 as the optimal DR. The investigated multi-barrier approach is an interesting option for OMW co-treatment in IWTPs to successfully address the challenge of TPHs degradation and drastically reduce the volume of the biological process unit (4 times lower than MBBR treatment alone).

<p>Olive oil extraction processes generate three phases: Olive oil, solid residue (pomace) and aqueous liquor Olive Mill Wastewater (OMW). OMW causes serious environmental deteriorations such as coloring of natural waters, alteration of soil quality, phytotoxicity and odor nuisance. The direct discharge of this effluent into the soil bring various negative effects on the environment, due to its high load of organic matter and phenolic compounds. Coagulation, flocculation and their combination processes are among the most applied processes for wastewater treatment. The application of coagulation technique using mineral and inorganic polymeric coagulants and acid cracking is not always effective to reduce COD and phenolic compounds from OMW except lime. Although direct flocculation is a low treatment cost, use less chemical and produce less sludge, the efficiency of COD and phenolic compounds removal remain very low. Coagulation-flocculation process is developed in order to enhance the removal efficiency of organic matter from OMW by optimizing the operating conditions. However, many studies showed that the combination of various cationic organic coagulant and flocculant agents did not show any significant decrease of COD and phenolic compounds except for lime combination. In the present review, recent research studies dealing with the application of coagulation/flocculation for removal of phenolic compounds and COD from OMW are presented and compared. Furthermore, the main factors that influence the selection between coagulation, direct flocculation and coagulation-flocculation are presented and the principal removal mechanisms are discussed.</p>

This study was carried out to investigate the potential for the usability of treated olive mill wastewater (OMW) as an organic amendment in agricultural soils under Mediterranean climate conditions. OMW was treated by two different treatment processes as economical (E-OMW) and advanced (A-OMW). The treated OMWs and raw OMW (R-OMW) were applied to a loamy soil at a rate of 100 m3 ha-1 year-1 for 2 years. Soils were sampled 15 days and about 5 months (at harvest) after OMW application for chemical and microbial analyses in each year. The total concentrations of N, P, Cu, Zn, and phenol of R-OMW decreased after both treatment processes while salinity (EC) and the total amounts of K, Na, and Ca increased. The applications of OMW caused changes in soil chemical (pH, EC, Pext, Kext) and microbial (microbial biomass-C (MB-C), microbial biomass-N (MB-N), basal soil respiration (BSR), N-mineralization (N-min)) characteristics (P < 0.05). In the second year of the experiment, initial samplings showed that the values of soil pH and EC increased significantly under all OMW applications compared to the control. High Pext concentrations were determined in soils amended with R-OMW, while there were high Kext concentrations in soils amended with the treated OMWs. The increases determined in MB-C and MB-N at all sampling times resulted in high MB-C/TOC and MB-N/TN ratios in soils amended with the treated OMWs. The wheat grain yield over the 2-year period showed that the application of the treated OMWs had a positive effect. It was determined that no negative effects occurred for either soil properties or wheat growth with the treated OMW applied at rates of up to 100 m3 ha-1. The addition of treated OMW after removal of its phenolic components may be considered as a good option for evaluating this waste in countries where OMW causes serious environmental pollution.

This research was developed in the sub-basin of the Puyo River, Province of Pastaza, Ecuador, in the years 2015 and 2018 had as objective: To characterize the environmental quality of water, in different sectors of the sub-basin of the Puyo River, including the main tributaries. The zones were classified as high, urban and low. A monitoring was carried out in the main channel and its tributaries in 28 points, registering values ​​of conductivity, pH, temperature and oxygen saturation, chemical oxygen demand, biochemical oxygen demand, total and fecal coliforms, and 413 surveys were applied to identify the Main types of activities that take place in the areas surrounding the main course and tributaries. The results showed differences in the concentrations of the different parameters in the dates and monitoring points, reporting higher concentrations of BOD5, total and fecal coliforms, the areas of the urban area. The correlation analysis showed significant relationships between the variables studied except for oxygen saturation. The analysis of variance showed significant differences between the zones for electrical conductivity, concentration of fecal and total coliforms. Surveys reveal that the majority of wastewater is deposited directly into the sewer system and the main channel of the river. It is concluded that the behavior of the different registered variables differs between the main body and tributaries, increasing the concentrations of total Coliforms, fecal from the urban area in the main body and differing the behavior of the rest of the parameters in the three zones.

A collaborative study was conducted in 18 laboratories to assess the performance of the hydrophobic grid membrane filter method against that of the AOAC official first action method 46.013-46.016 for enumerating total and fecal coliforms and Escherichia coli. The study was carried out on frozen breaded fish, raw comminuted poultry, unroasted walnut pieces, ground black pepper, and cheddar cheese. The hydrophobic grid membrane filter method recovered significantly larger numbers of target bacteria in 7 of the food/analysis combinations: fecal coliforms in fish; E. coli in poultry; fecal coliforms and E. coli in walnuts; and total coliforms, fecal coliforms and E. coli in black pepper. Random error (Sr2) associated with the hydrophobic grid membrane filter method was significantly lower than that of the reference method in over 30% of the paired sample series. The hydrophobic grid membrane filter method for total coliform, fecal coliform, and E. coli enumeration in foods has been adopted official first action.

The quality of drinking water at the point of delivery to the consumer is crucial in safeguarding consumer&rsquo;s health. The current study was undertaken to assess the changes in residual chlorine content with distance in water distribution system in Gwalior city of Madhya Pradesh and assess its relation with the occurrence of total and faecal coliforms. Water samples were collected from the exit point of the treatment plant and taps at consumer households at an interval of 1 to 2 km. A total of 56 water samples were tested to determine residual chlorine content and presence of total and fecal coliforms using standard methods. Average concentrations of residual chlorine from all sampling location were between 0.08 to 0.98 mg/L. Total coliform was found at most of the sampling locations in the range of 0.82 to 7.15 MPN/100 ml. The fecal coliform at all sampling locations was found in the range of 0 to 4.10 MPN/100 ml. With time, the residual chlorine in the transported water dechlorinates. After covering some distance, the residual chlorine of the water was completely diminished thereby supporting massive microbial growth. The study proposed the likely causes of the transit dechlorination of water and recommended carrying out compulsory chlorination at water sources while maintaining reasonable residuals at the consumers&rsquo; end to eliminate the bacteriological contamination. Key words: Residual chlorine, total and fecal coliforms, drinking water chlorination, water contamination.

Olive mill waste water samples from different traditional mills were analyzed for their microbiota and the physicochemical characteristic. A survey of the most frequent microorganisms including standard plate count (SPG), counts of the indicator microorganisms (total and fecal coliforms and enterococci) staphylococci, Salmonella, sporeforming bacteria (Clostridium and Bacillus), yeasts and molds and the lipolytic microorganisms. The physicochemical analysis grouped the determination of pH, salinity, density, conductivity, alkalinity, acidity, total dry matter, non volatile dry matter, suspended solids, organic carbon, ammoniacal nitrogen, organic nitrogen, fat, polyphenols, polyphosphates, sodium and potassium and the BOD and COD. Results showed that the physicochemical factors were higher than the reported values in other countries. The microbial load was low and mainly made of yeasts and molds as well as the lactic acid bacteria. A net difference between the traditional mill samples and the industrial samples was observed for both analyses.

Purpose In waters and wastes, direct pathogen detection is difficult and time consuming. Therefore, coliforms are used as indicators to measure the presence of pathogens. Composts originated from extrements, sewage sludges and plant wastes those contact with manures may have potential health hazard to human. Therefore, the detection of coliforms both during composting and in the obtained composts is used to investigate the presence of pathogens for determination of the potential health risk. Methods In this study, the effect of six different aeration rates on elimination of total and faecal coliform bacteria was investigated during in-vessel aerobic composting of vegetableâfruit wastes. Total coliform and faecal coliform numbers in the samples were measured by the most probable number method. Results Coliforms significantly increased before the thermophilic stage except the faecal coliforms in the reactor which operated with the lowest aeration. The coliforms suddenly decreased after thermophilic stage in all reactors. Total coliforms reduced within the range of 78.2â99.9 % while faecal coliforms reduced within the range of 72.5â99.9 % after the thermophilic stage. At the end of the composting period (day 18), total coliforms and faecal coliforms reduced within the range of 99.9â100 %. Conclusions Although all the aeration rates used in the present study were effective for the elimination of coliforms, the lowest faecal coliform number was seen in the reactor that had the lowest aeration rate. At the end of the study, the faecal coliform numbers in all reactors confirmed some limits for the application activities of composts.

Control of microbial growth in bakery products fortified with polyphenols recovered from olive mill wastewater

Treated effluent discharge can significantly alter river water quality by affecting parameters such as pH, turbidity, conductivity, and coliform levels, thereby posing risks to both ecosystems and human health. This study evaluated the impact of effluent discharge from the Wupa Wastewater Treatment Plant Abuja, Nigeria on the water quality of the Wupa River. A refined parametric water quality index was developed to enhance monitoring precision, as traditional indices often lack sensitivity to variations in individual parameters. Water samples were collected during the rainy season’s peak mixing period (June–August) from six stations: the influent (INF), effluent (EFF), the point of discharge (POD), upstream of POD (UPOD), and two downstream locations (1kmPOD and 2kmPOD). The samples were analyzed for physical appearance, pH, temperature, conductivity, turbidity, total coliforms, and fecal coliforms. The parametric index incorporated three components: concentration factor, percentage equivalence, and percentage change, to capture parameter-specific changes. Results revealed distinct spatial variations in water quality across the stations. The INF had poor quality, with turbidity between 203–209NTU, total coliforms up to 6000/100 mL, and fecal coliforms also reaching 6000/100 mL, along with a darkish appearance. The EFF showed improvement, with turbidity reduced to 16–19NTU and total coliforms to 400–2000/100 mL, indicating partial treatment success. The UPOD station showed moderate pollution, with turbidity between 69–94 NTU, total coliforms at 600–3000/100 mL, and fecal coliforms ranging from 880–1600/100 mL. At the POD, contamination intensified: turbidity rose to 84–95 NTU, total coliforms increased to 1750–4500/100 mL, and fecal coliforms to 400–900/100 mL. Further downstream, values remained high—turbidity (80–85 NTU), total coliforms (650–3000/100 mL), and fecal coliforms (700–1220/100 mL). pH remained nearly neutral (6.91–7.65), and temperature ranged from 23.8–28.3 °C. Statistical analysis (ANOVA and t-tests) showed significant differences (p < 0.05) in conductivity (245–345 µS/cm), turbidity, and all coliform counts across stations, while differences in pH and temperature were not significant. The parametric index further revealed that treated effluent influenced river quality through elevated turbidity, minor pH variations (+2% in June, −2% to −4% in July and August), and significant increases in coliform levels. Temperature at the POD rose by 5%–12% but declined downstream. Conductivity increased at the POD(+15.5% to +23%) and remained elevated downstream. Turbidity also increased at the POD(+21.7% in June) before declining. Total coliforms surged at the POD(+50% to +191.7%), with residual contamination downstream, while fecal coliforms showed mixed patterns. These findings indicate that although some parameters return to near-background levels within 1 km, microbial contamination persists, raising concerns about waterborne diseases and the safety of downstream water use. The study concludes that the parametric water quality index is effective in assessing site-specific impacts of effluent discharge and underscores the urgent need for improved wastewater treatment and ongoing water quality monitoring to protect public health and environmental integrity.