Cheese Whey Wastewater Research Articles

Aerobic Biodegradation of Precoagulated Cheese Whey Wastewater

Prior to the application of an aerobic biological process, cheese whey wastewater has been pretreated by means of a precipitation stage by adding either NaOH or CaOH2. Both precipitating agents reduce roughly 50% of the raw wastewater chemical oxygen demand (COD). The sludge generated in the prestage shows acceptable settling properties, although solids from the CaOH2-treated effluent are better separated from the liquid bulk than those formed in NaOH-processed wastewater. In both situations, the presedimentation stage renders a supernatant more prone to biodegradation than the untreated effluent. The previous statement is corroborated by the determination of some biological kinetic parameters. Under the operating conditions used in this work, sludge generation after the biological process is reduced to a minimum. The sludge generated shows good settling properties, especially for those experiments in which CaOH2 has previously been added.

Treatment of Cheese Whey Wastewater: Combined Coagulation−Flocculation and Aerobic Biodegradation

Cheese wastewater has been treated by means of a coagulation-flocculation process. Three different coagulants have been used, namely, FeSO(4), Al(2)(SO(4))(3), and FeCl(3). When FeSO(4) was used, the optimum conditions were obtained using 250 ppm of the salt at pH 8.5. At these conditions, 50 and 60% of chemical oxygen demand (COD) and biological oxygen demand (BOD) were reduced, respectively. Al(2)(SO(4))(3) achieved slightly lower reductions of COD and BOD; however, the amount needed was significantly higher (1000 ppm). When FeCl(3) was added, similar results to those obtained with FeSO(4) were experienced; again, 250 ppm was enough to eliminate COD and BOD contents in the range of 40-60%, depending upon operating conditions. The sludge formed in the coagulation-flocculation process did show acceptable settling properties, which is crucial in settling tank design. A first approach to sedimentation tank design is also conducted on the basis of experimental results. The aerobic biodegradation of cheese whey wastewater achieves the reduction of the main contaminant indicators (COD and BOD) to values close to 100%; however, effluents coming from the coagulation-flocculation pre-stage necessitate half of the time required by the non-pretreated raw wastewater.

The effect of dilution and l-malic acid addition on bio-hydrogen production with Rhodopseudomonas palustris from effluent of an acidogenic anaerobic reactor

In this study, H 2 was produced from cheese whey wastewater in a two-stage biological process: i) first stage; thermophilic dark fermentation ii) second stage; the photo fermentation using Rhodopseudomonas palustris strain DSM 127 ( R. palustris). The effect of both dilution and addition of l-malic acid on the hydrogen production was investigated. Among the dilution rates used, 1/5 dilution ratio was found to produce the best hydrogen production (349 ml H 2/g COD fed). On the other hand, It was seen that the mixing the effluent with l-malic acid at increasing ratios had further positive effect and improved the hydrogen production significantly. It was concluded that dilution of the feeding helps to reduce the nitrogen content and the volatile fatty acid content that might be otherwise harmful to the photo-heterotrophic organisms. Overall hydrogen production yield (for dark + photo fermentation) was found to vary 2 and 10 mol H 2/mol lactose. Second conclusion is that cheese whey effluent should be mixed with a co-substrate containing l-malic acid such as apple juice processing effluents before fed into the photo fermentation reactor.

Optimization of Basal Medium for Fermentative Hydrogen Production from Cheese Whey Wastewater

In this study, optimal basal medium composition for fermentative hydrogen production from cheese whey wastewater was investigated in batch tests. Twenty-five different basal medium formulas was prepared, each containing trace metals concentration (Co, Ni, Zn: 0–5 mg/l), macro elements concentration (Mg: 0–200 mg/l; Mn: 0–10 mg/l, Fe: 0–100 mg/l, Ca: 0–1000 mg/l), C/N ratio of 5–50, and yeast extract and l-cycteine concentrations (0–500 mg/l). Each of the experimental setups was conducted as triplicates in 100-ml serum vials at pH 5.5 under mesophilic conditions (36 ± 1°C). Granular biomass obtained from an industrial scale upflow anaerobic sludge bed bioreactor was used as an initial inoculum. Considering the hydrogen production efficiencies obtained in this study (max. 3.5 mol H2/mol lactoseconsumed and 218.6 ml H2 /g lactoseconsumed), a successful nutrient formulation for optimum hydrogen production from cheese whey was proposed as follows; CoCl2, NiCl2, ZnCl2: 1.25–2.5 mg/l; CaCl2: 250–500 mg/l: MgCl2: 50–150 mg/l; MnCl2: 2.5–5 mg/l; FeCl2: 50–100 mg/l; yeast extract: 125–250 mg /l; L-cysteine: 125–250 mg /l and C/N ratio: 30–40.

Continuous fermentative hydrogen production from cheese whey wastewater under thermophilic anaerobic conditions

Hydrogen (H2) production from cheese processing wastewater via dark anaerobic fermentation was conducted using mixed microbial communities under thermophilic conditions. The effects of varying hydraulic retention time (HRT: 1, 2 and 3.5 days) and especially high organic load rates (OLR: 21, 35 and 47 g chemical oxygen demand (COD)/l/day) on biohydrogen production in a continuous stirred tank reactor were investigated. The biogas contained 5–82% (45% on average) hydrogen and the hydrogen production rate ranged from 0.3 to 7.9 l H2/l/day (2.5 l/l/day on average). H2 yields of 22, 15 and 5 mmol/g COD (at a constant influent COD of 40 g/l) were achieved at HRT values of 3.5, 2, and 1 days, respectively. On the other hand, H2 yields were monitored to be 3, 9 and 6 mmol/g COD, for OLR values of 47, 35 and 21 g COD/l/day, when HRT was kept constant at 1 day. The total measurable volatile fatty acid concentration in the effluent (as a function of influent COD) ranged between 118 and 27,012 mg/l, which was mainly composed of acetic acid, iso-butyric acid, butyric acid, propionic acid, formate and lactate. Ethanol and acetone production was also monitored from time to time. To characterize the microbial community in the bioreactor at different HRTs, DNA in mixed liquor samples was extracted immediately for PCR amplification of 16S RNA gene using eubacterial primers corresponding to 8F and 518R. The PCR product was cloned and subjected to DNA sequencing. The sequencing results were analyzed by using MegaBlast available on NCBI website which showed 99% identity to uncultured Thermoanaerobacteriaceae bacterium.

The treatment of cheese whey wastewater by sequential anaerobic and aerobic steps in a single digester at pilot scale

The treatment of reconstituted whey wastewater was performed in a 400 L digester at 20 °C, with an anaerobic digestion step, followed by a step of aerobic treatment at low oxygen concentration in the same digester. In a first set of 48 cycles, total cycle time ( T C) of 2, 3 and 4 days were tested at varying organic loading rates (OLR). The COD removal reached 89 ± 4, 97 ± 3 and 98 ± 2% at T C of 2, 3 and 4 days and OLR of 0.56, 1.04 and 0.78 gCOD L −1 d −1, respectively. The activity of the biomass decreased for the methanogenic population, while increasing by 400% for the acidogens, demonstrating a displacement in the predominant trophic group in the biomass bed. A second set of 16 cycles was performed with higher soluble oxygen concentration in the bulk liquid (0.5 mg L −1) during the aerobic treatment at a T C of 2 days and an OLR of 1.55 gCOD L −1 d −1, with a soluble COD removal of 88 ± 3%. The biomass specific activities showed a compartmentalization of the trophic group with methanogenic activity maintained in the biomass bed and a high acidogenic activity in the suspended flocs.

Comparative Evaluation of Bio-Hydrogen Production From Cheese Whey Wastewater Under Thermophilic and Mesophilic Anaerobic Conditions

Hydrogen production from cheese whey wastewater via dark fermentation was conducted using mixed culture under mesophilic (36°C ± 1) and thermophilic (55°C ± 1) conditions, respectively. The hydrogen yields and specific hydrogen production rates were found as follows: mesophilic: 9.2 mmol H2 /g COD (chemical oxygen demand) and 5.1 mL H2 /g VSS h; thermophilic: 8.1 mmol H2 / g COD and 1.1 mL H2 /g VSS h. The reaction mixture for the mesophilic condition was composed of acetate (0.3–14.7%) and iso-butyrate (85–98%), plus other volatile fatty acids. On the other hand, the reactor mixture for the thermophilic condition was composed of acetate (1–43%) and iso-butyrate (29–46%).

Ecological clarification of cheese whey prior to anaerobic digestion in upflow anaerobic filter

Anaerobic digestion of cheese whey wastewaters (CW) was investigated in a system consisting of an ecological pretreatment followed by upflow anaerobic filter (UAF). The pretreatment was conducted to solve the inhibition problems during anaerobic treatment of CW caused by the amounts of fats, proteins and carbohydrates and to avoid the major problems of clogging in the reactor. The optimized ecological pretreatment of diluted CW induce removal yields of 50% of chemical oxygen demand (COD) and 60% of total suspended solids (TSS) after acidification by Lactobacillus paracasei at 32 °C during 20 h and neutralization with lime. The pretreated CW was used to feed UAF (35 °C). The effects of organic loading rate (OLR) and hydraulic retention time (HRT) on the pretreated CW anaerobic degradation were examined. The average total COD removals achieved was 80–90%. The performance of the reactor was depressed by increasing the COD concentration to 20 g/l (OLR = 4 g COD/l d) and the COD removal efficiency was reduced to 72%. Significant methane yield (280 l/kg COD removal) was obtained at an HRT of 2 days.

Computer-aided process design, economic evaluation and environmental impact assessment for treatment of cheese whey wastewater

Efficient software was used for the comparison of five alternative scenarios for the treatment of cheese whey wastewater resulting from a Cheddar cheese factory. Scenario 1 deals with a cheese whey wastewater treatment plant that produces butter, whey protein concentrate and food-grade ethanol. In scenario 2 the butter-making section is similar to the basic process (scenario 1) with some differences in the concentration of whey proteins and in the removal of residual minerals from water. In scenario 3 the plant produces Manouri (a type of cream cheese) instead of butter. In scenario 4 the plant produces two types of whey protein concentrate (WPC), namely, a rich in whey lipids (WPC 2) and the other a highly purified protein concentrate possessing improved functional properties (WPC 1). In addition a process that produces pure lactose has replaced the ethanol section. In scenario 5 the plant produces butter, whey protein isolate (WPI) containing 95% protein and hydrolyzed-isomerized whey permeate syrup (HIPS). The economic comparison has shown that scenario 3 is the most profitable due to its high net present value (NPV) and low payback period as well as to its low production rate (40% of the full production rate) at the breakeven point. The environmental impact assessment demonstrated that scenario 4 is more environmentally friendly than the others due to the absence of biomass in the effluent.

Sludge characteristics and effect of crossflow membrane filtration on membrane fouling in a jet loop membrane bioreactor (JLMBR)

An aerobic jet loop membrane bioreactor (JLMBR) activated sludge process of 35 L working volume was used to investigate its applicability in industrial wastewaters, specifically cheese whey wastewater. A loading rate of 22.2 kg COD/(m 3 day) and 1.6 days of sludge age was achieved with 97% COD removal efficiency. During the study, the activated sludge was found non-settable and slimy characteristic and non-flocculating motile bacteria structure. Therefore, it was been conducted that the membrane separation was indispensable to obtain high performance from jet loop bioreactor (JLB). From the investigation of crossflow microfiltration characteristic of the system, it was found that the fluxes decreased and MFI increased with increasing MLSS concentration. The increasing crossflow velocity greatly reduced the cake formation on the membrane surface and increased the steady state permeate fluxes, decreasing specific cake resistance ( α) values. The cake layer was in a highly compressible form. The compressibility coefficient was calculated as 0.98. In addition to this, the pseudo gel concentration ( C G) on the membrane surface was calculated to be 73,130 mg/L. For the investigation of the membrane filtration mechanism, it was found that the fouling mechanism showed high compatibility with complete pore blocking model and particularly cake filtration model ( R 2 = 0.99).

Modeling of submerged membrane bioreactor treating cheese whey wastewater by artificial neural network

A submerged membrane bioreactor receiving cheese whey was modeled by artificial neural network and its performance over a period of 100 days at different solids retention times was evaluated with this robust tool. A cascade-forward network was used to model the membrane bioreactor and normalization was used as a preprocessing method. The network was fed with two subsets of operational data, with two-thirds being used for training and one-third for testing the performance of the artificial neural network. The training procedure for effluent chemical oxygen demand (COD), ammonia, nitrate and total phosphate concentrations was very successful and a perfect match was obtained between the measured and the calculated concentrations. The results of the confirmation (or testing) procedure for effluent ammonia and nitrate concentrations were very successful; however, the results of the confirmation procedure for effluent COD and total phosphate concentrations were only satisfactory.

Selective optimization in thermophilic acidogenesis of cheese-whey wastewater to acetic and butyric acids: partial acidification and methanation

For partial acidogenesis of cheese-whey wastewater, a set of experiments were carried out to produce short-chain volatile fatty acids (VFA) in laboratory-scale continuously stirred tank reactors (CSTR). The maximum rate of acetic and butyric acid production associated with simultaneous changes in hydraulic retention time (HRT), pH, and temperature was investigated, in which the degree of acidification of the whey to the short-chain VFAs was less than 20% of the influent chemical oxygen demand (COD) concentration. Response surface methodology was successfully applied to determine the optimum physiological conditions where the maximum rates of acetic and butyric acid production occurred. These were 0.40-day HRT, pH 6.0 at 54.1°C and 0.22-day HRT, pH 6.5 at 51.9°C, respectively. The optimum conditions for acetic acid production were selected for partial acidification of cheese-whey wastewater because of a higher rate in combined productions of acetic and butyric acids than that at optimum conditions for butyric acid production. A thermophilic two-phase process with the partial acidification followed by a methanation step was operated. Performance of the two-phase process was compared to the single-phase anaerobic system. The two-phase process clearly showed a better performance in management of cheese-whey wastewater over the single-phase system. Maximum rate of COD removal and the rate of methane production in the two-phase process were, respectively, 116% and 43% higher than those of the single-phase system.

Characterization and comparison of biomasses from single- and multi-fed upflow anaerobic filters

Two lab-scale single-fed (SFR) and multi-fed (MFR) upflow anaerobic filters treating a cheese whey wastewater were operated at Organic Loading Rates (OLR) higher than 20 kg COD/m 3/d. The occluded and attached biomass values and the hydrolytic, acidogenic and methanogenic activities of sludges at different heights were determined in the filters. The feeding policy affected both biomass concentration (attached and occluded) and activity. Although a lower amount of biomass was retained in the MFR, the distribution along the filter was more homogeneous than in the SFR. The specific activities of the different trophic groups were higher in the MFR. Because of both facts, the methanogenic capacity of the MFR was higher than that in the SFR, this resulting in a more efficient operation, especially when operated at the highest OLR.

Anaerobic treatment of high-strength cheese-whey wastewaters in laboratory and pilot UASB-reactors

Start-up of the laboratory (3 l) UASB-reactor treating raw high-strength (up to 77 g COD/l) cheese-whey wastewaters as well as the treatment efficiencies (TE) and the maximal admissible organic loading rates (OLR) have been investigated under mesophilic (35°C) and submesophilic (20–30°C) conditions. A stable operation of the reactor with the TE higher than 90% on the total COD has been demonstrated up to the OLR of 28.5 and 9.5 g COD/l·day for mesophilic and submesophilic regimes, respectively. A successful start-up of the pilot (10.74 m 3) non-thermostated UASB-reactor treating raw cheese-whey wastewaters at ambient temperatures (ca. 24°C) has been completed in 3 months. Further exploitation of the reactor at the design OLR of 6.5 g COD/l·day showed its good operational stability with the TE close to 95% on the basis of total COD. After a proper start-up, the UASB-reactors can cope with preacidificated cheese-whey wastewaters (pH of about 4) even at elevated OLR that eliminates the necessity of alkalinity supplementation.

Influence of immobilization supports on the kinetic constants of anaerobic digestion of cheese whey

Three materials of different structure, sepiolite, saponite and bentonite, assayed as supports for the microorganisms effecting anaerobic digestion, were found to behave differently towards cheese whey wastewater from a kinetic point of view. Assuming the overall anaerobic digestion process to conform to first-order kinetics, the apparent kinetic constant for the digester including sepiolite as support was 2.44 days −1, while that of the digester using the saponite and bentonite support was 2.20 days −1 and 0.70 days −1, respectively. Thus, the support used to immobilize the microorganisms that mediate the process had a marked influence on the constant. This was found significant at 95% confidence level. The yield coefficients, Y p/s, were 0.336, 0.329 and 0.311 litres CH 4 STP/g COD for the sepiolite, saponite and bentonite supports, respectively.