Improvement of fermentative decolorization of olive mill wastewater by Lactobacillus paracasei by cheese whey's addition

Preparation of Hydrolyzed Sugarcane Molasses as a Low-Cost Medium for the Mass Production of Probiotic Lactobacillus paracasei ssp. paracasei F19

In this study, sugarcane molasses (SCM) was pre-treated in a low-cost fermentation medium to produce probiotic biomass of Lactobacillus paracasei ssp. paracasei F19 (LPPF19) with the combination of dilution, centrifugation, and acid hydrolysis (5 molar sulfuric acid, 60 °C/2 h). Microtox analysis, inductively coupled mass spectrometry (ICP-MS), and high-performance liquid chromatography (HPLC) were used to measure the effects of SCM pretreatment on the fermentation process. The results showed that the hydrolysis of sucrose into glucose and fructose was 98%, which represented an increase of 44.4% in the initial glucose content (fermentation-limiting sugar), and harmful heavy metals, such as arsenic, cadmium, and lead, were reduced by 50.3, 60.0, and 64.3%, respectively. After pretreatment, with the supplementation of only yeast extract and salts (Na, K, Mg, and Mn), a biomass of 9.58 log CFU/mL was achieved, approximately ten times higher than that for the control medium used (MRS/DeMan, Rogosa, and Sharpe). The cost reduction achieved compared to this commercial medium was 68.7% in the laboratory and 78.9% on an industrial scale. This work demonstrated that SCM could be used in a cheaper and more effective alternative fermentation to produce LPPF19.

Valorization of vinasse and whey to protein and biogas through an environmental fungi-based biorefinery

Vinasse and whey are wastewaters that are produced in large quantities in the sugar-to-ethanol and dairy industries, respectively. They pose a considerable threat to the environment due to the high concentration of nutrients and COD. In this study, the potential of producing protein-rich fungal biomass and biomethane from vinasse and whey through a two-stage biorefinery was examined. In the first stage, an edible and safe for human filamentous fungus, Neurospora intermedia, was cultivated on these wastewaters. To maximize the fungal biomass yield, the cultivation parameters, i.e., pH, vinasse to whey ratio, incubation time, and nutrients supplementation, were optimized. The highest yield of 12.0 g biomass per L of wastewaters was obtained by cultivation at pH 6.5 and vinasse to whey ratio of 25:75 (v/v) for 96 h with nitrogen source supplementation. The N. intermedia biomass contained about 45% protein and noticeable essential amino acid contents, comparable to commercial sources of protein for aquatic feed such as soybean meal and fishmeal. In the second stage, the effluent of fungal cultivation was anaerobically digested to produce 425 mL/g VS biomethane. Overall, 1 m³ of wastewater yielded 5.4 kg crude protein and 10.3 m³ methane, accompanied by 93.3% COD removal.

Biodegradation of olive mill wastewater phenolic compounds in a thermophilic anaerobic upflow packed bed reactor and assessment of their toxicity in digester effluents

The extent of phenolic compounds' biodegradation was assessed utilizing un-treated olive mill wastewater (OMWW) fed to a high-rate thermophilic (55 ^οC) anaerobic upflow packed bed reactor (UPBR) and digester effluents (DEs) collected in different hydraulic retention times (HRTs) under steady-state operating conditions. In parallel, the toxicity of each sample was evaluated by performing the microbiotest Thamnotoxkit F™. The outcomes indicate complete biodegradation of 6 phenolic compounds-vanillic acid (VA), caffeic acid (CA), syringic acid (SA), o-coumaric acid (o-CA), oleuropein (OLEU), 4-ethylphenol (4-EP)-and notable removals of hydroxytyrosol (HT) and tyrosol (TYR), reaching up to 94.87 ± 0.04% and 93.92 ± 0.33%, respectively. 4-hydroxybenzoic acid (PHBA), p-coumaric acid (p-CA) and 3,4-dihydroxybenzoic acid (DBA) were recognized as the most recalcitrant and persistent compounds in the anaerobic effluents, being capable of modulating the toxic potential of DEs.

Bioreduction of azo dyes was enhanced by in-situ biogenic palladium nanoparticles

Biogenic nanoparticles are promising materials for their green synthesis method and good performance in stimulation on reduction of environmental contaminants. In this study, Pd(0) nanoparticles (bio-Pd) were generated by Klebsiella oxytoca GS-4-08 in fermentative condition and in-situ improved the azo dye reduction. The bio-Pd was mainly located on cell membrane with a size range of 5-20 nm by TEM and XRD data analyses. Anthraquinone-2-disulfonate (AQS) greatly increased the reduction rate of Pd(II) with a reduction efficiency as high as 96.54 ± 0.23% in 24 h. The quinone respiration theory, glucose metabolism and the biohydrogen pathway were used to explain the enhancement mechanism of the in-situ generated bio-Pd on azo dye reduction. These results indicate that the in-situ generated bio-Pd by K. oxytoca strain is efficient for azo dye reduction without complex preparation processes, which is of great significance for the removal and subsequent safe disposal of hazardous environmental compounds.

Stability of continuous and fed batch sequential anaerobic-anoxic-aerobic moving bed bioreactor systems at phenol shock load application

The stability of two sequential moving bed bioreactor systems operated in anaerobic-anoxic-aerobic continuous moving bed bioreactor (CMBR: R1-R2-R3) and semi-continuous fed batch moving bed bioreactor (FMBR: B1-B2-B3) modes was assessed for phenol shock load (PSL) applications in the presence of thiocyanate and ammonia. Both the systems were exposed to 3000 mg phenol/L (PSL-I) and 3500 mg phenol/L (PSL-II) for 3 days each from initial 2500 mg phenol/L without any intermediate concentration at 6 days HRT (hydraulic retention time). The effect of PSL-I on R1 was reversible within 10-12 days. At PSL-II, R1 required 2 days stop of feed for stability and resumed removal efficiency of phenol (15%) and COD (3%). R2 remained robust to sustain both PSLs and recovered within 15 days from peak influent concentrations of 1727 mg phenol/L (removal: 67%) and 324 mg SCN--/L (removal: 68-70%). In B1, effluent COD increased by 2%, though effluent phenol decreased by 3% than the pre-shock condition after PSL-I exposure. B2 acted similar to R2 when exposed to PSLs. The effect of PSL-I on R3 and B3 was negligible. However, at PSL-II R3 became vulnerable for nitrification, whereas phenol, COD and SCN- removal remained unaffected. In B3, PSL-II caused a decrease in phenol, SCN- and NH+4-N removal. In B3, stop of feed for 4 days also did not improve nitrification. The performance of the CMBR system was better than that of the FMBR system for organic shock load exposure in the presence of multiple pollutants.

Anaerobic digestion challenge of raw olive mill wastewater

Olive mill wastewater (OMW) was digested in its original composition (100% v/v) in an anaerobic hybrid. High concentrations (54-55 kg COD m(-3)), acid pH (5.0) and lack of alkalinity and nitrogen are some OMW adverse characteristics. Loads of 8 kg COD m(-3) d(-1) provided 3.7-3.8 m3 biogas m(-3) d(-1) (63-64% CH4) and 81-82% COD removal. An effluent with basic pH (8.1) and high alkalinity was obtained. A good performance was also observed with weekly load shocks (2.7-4.1, 8.4-10.4 kg COD m(-3) d(-1)) by introducing piggery effluent and OMW alternately. Biogas of 3.0-3.4 m3 m(-3) d(-1) (63-69% CH4) was reached. Developed biomass (350 days) was neither affected by raw OMW nor by organic shocks. Through the effluents complementarity concept, a stable process able of degrading the original OMW alone was obtained. Unlike what is referred, OMW is an energy resource through anaerobiosis without additional expenses to correct it or decrease its concentration/toxicity.

Time-dependent evolution of olive mill wastewater sludge organic and inorganic components and resident microbiota in multi-pond evaporation system

The physico-chemical and microbiological characterizations of olive mill wastewater sludge (OMWS) were investigated in five OMW evaporation ponds of the open-pond system in Sfax (Tunisia), during the olive oil production period in 2004. Time-dependent changes in both physico-chemical parameters and the microbiota were investigated. Mathematical models and principal component analysis (PCA) were used to establish the correlations between the studied parameters. During the effluent time-dependent changes in the ponds, the result of OMWS analysis showed an increase of sludge index (SI), ash content, total solids (TS), volatile solids (VS), ethyl acetate extractive (EAE) and total phosphorus (Total P), as well as microbial flora especially the yeasts and moulds. The SI, TS, VS and Total P changes with time fit a simple linear equation, while EAE, phenols and NH(4)(+) fit a second-degree polynomial model. The PCA analysis exhibited three correlated groups. The first group included temperature, ash content, evaporation, SI, TS, VS, Total P, EAE, yeasts and moulds. The second group was made by bacteria and moisture; and the third group by NH(4)(+), oil and phenol. Such modelling might be of help in the prediction of OMW changes in natural evaporation ponds.