We employed stable isotope probing (SIP) with 13C-labeled hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) to identify active microorganisms responsible for RDX biodegradation in groundwater microcosms. Sixteen different 16S rRNA gene sequences were derived from microcosms receiving 13C-labeled RDX, suggesting the presence of microorganisms able to incorporate carbon from RDX or its breakdown products. The clones, residing in Bacteroidia, Clostridia, α-, β- and δ-Proteobacteria, and Spirochaetes, were different from previously described RDX degraders. A parallel set of microcosms was amended with cheese whey and RDX to evaluate the influence of this co-substrate on the RDX-degrading microbial community. Cheese whey stimulated RDX biotransformation, altered the types of RDX-degrading bacteria, and decreased microbial community diversity. Results of this study suggest that RDX-degrading microorganisms in groundwater are more phylogenetically diverse than what has been inferred from studies with RDX-degrading isolates.

In this study, a novel two-step integrated process is proposed to facilitate the microalgae biofuel production as well as fresh cheese whey wastewater (FCWW) treatment simultaneously. The pre- and post-treatment of high-strength FCWW were performed by means of coagulation and algal cultivation, respectively. The pre-treatment of FCWW for maximum removal of chemical oxygen demand (COD), turbidity (TUR) and total solids (TS) as responses was obtained by statistical optimization of coagulation parameters. The maximum removal of COD, TUR and TS at the optimum level of variables was obtained as 68.09%, 47.80% and 73.63%, respectively. The pre-treated FCWW was further treated by Chlorella pyrenoidosa and observed a significant reduction in the above-mentioned responses (87–94%). The maximum algal biomass yield and lipid productivity were observed as 2.44 g L⁻¹ and 77.41 mg L⁻¹ day⁻¹, respectively. Based on promising results of FCWW treatment and its use as a third-generation biodiesel feedstock, a cost-benefit analysis of the developed process was assessed for microalgal oil production. The total profit earned by the integrated process model was $9.59 million year⁻¹. Accordingly, the estimated production cost of algal oil (TAG) from the developed system was estimated to be $79.03 per barrel.

This paper summarizes findings from a study in which the biochemical methane potential (BMP) of cheese whey was investigated. The cheese whey and mixtures of it with various co-substrates were used in anaerobic serum bottles for a period of about 90 days. The effects of inoculum were also investigated using granular anaerobic sludge from gum industry and anaerobic sludge from a municipal wastewater treatment plant. A total of 14 groups were set with two different inoculums and various substrate mixtures. The highest cumulative biogas and methane production were observed as 1229 mL and 790 mL, respectively, for a mixture of 50% whey, 33% slaughterhouse wastewater, and 17% cattle manure inoculated with granular anaerobic sludge. The highest BMP was obtained for whey (diluted to 13%) inoculated with anaerobic sludge as 360 mLCH₄/gCODₐddₑd. Methane percentages in headspace for all serum bottles were above 50%. Several kinetic models to predict biogas production were calibrated. Results showed that the first-order model and the transference function showed the best prediction performance for most of the serum bottles.

Large quantities of waste biomass are generated annually worldwide by many industries and are vastly underutilized. However, these wastes contain sugars and other dissolved organic matter and therefore can be exploited to produce microbial biopolymers. In this study, four selected Halomonas strains, namely, Halomonas caseinilytica K1, Halomonas elongata K4, Halomonas smyrnensis S3, and Halomonas halophila S4, were investigated for the production of exopolysaccharides (EPS) using low-cost agro-industrial wastes as the sole carbon source: cheese whey, grape pomace, and glycerol. Interestingly, both yield and monosaccharide composition of EPS were affected by the carbon source. Glucose, mannose, galactose, and rhamnose were the predominant monomers, but their relative molar ratio was different. Similarly, the average molecular weight of the synthesized EPS was affected, ranging from 54.5 to 4480 kDa. The highest EPS concentration (446 mg/L) was obtained for H. caseinilytica K1 grown on cheese whey that produced an EPS composed mostly of galactose, rhamnose, glucose, and mannose, with lower contents of galacturonic acid, ribose, and arabinose and with a molecular weight of 54.5 kDa. Henceforth, the ability of Halomonas strains to use cost-effective substrates, especially cheese whey, is a promising approach for the production of EPS with distinct physicochemical properties suitable for various applications.

Raw cheese whey wastewater (CWW) has been treated by means of FeCl₃ coagulation-flocculation, NaOH precipitation, and Ca(OH)₂ precipitation. Three different types of CWW were considered: without cheese whey recovery (CWW₀), 60 % cheese whey recovery (CWW₆₀), and 80 % cheese whey recovery (CWW₈₀). Cheese whey recovery significantly influenced the characteristics of the wastewater to be treated: organic matter, solids, turbidity, conductivity, sodium, chloride, calcium, nitrogen, potassium, and phosphorus. Initial organic load was reduced to values in the interval of 60–70 %. Application of FeCl₃, NaOH, or Ca(OH)₂ involved additional chemical oxygen demand (COD) depletions regardless of the CWW used. Under optimum conditions, the combination of 80 % cheese whey recovery and lime application led to 90 % reduction in COD. Turbidity (99.8%), total suspended solids (TSS) (98–99 %), oils and fats (82–96 %), phosphorus (98–99 %), potassium (96–97 %), and total coliforms (100 %) were also reduced. Sludge generated in the latter process showed excellent settling properties. This solid after filtration and natural evaporation can be used as fertilizer with limitations due to its saline nature. In an innovative, low-cost, and environmentally friendly technology, supernatant coming from the Ca(OH)₂ addition was naturally neutralized in 4–6 days by atmospheric CO₂ absorption without reagent addition. Consequently, a final aerobic biodegradation step can be applied for effluent polishing. This technology also allows for some atmospheric CO₂ mitigation. Time requirement for the natural carbonation depends on the effluent characteristics. A precipitate rich in organic matter and nutrients and depletions of solids, sodium, phosphorus, magnesium, Kjeldahl, and ammoniacal nitrogen were also achieved during the natural carbonation.

The efficiency of the anaerobic treatment of cheese whey (CW) at mesophilic conditions was investigated. In addition, the applicability of electrochemical oxidation as an advanced post-treatment for the complete removal of chemical oxygen demand (COD) from the anaerobically treated cheese whey was evaluated. The diluted cheese whey, having a pH of 6.5 and a total COD of 6 g/L, was first treated in a 600-L, pilot-scale up-flow anaerobic sludge blanket (UASB) reactor. The UASB process, which was operated for 87 days at mesophilic conditions (32 ± 2 °C) at a hydraulic retention time (HRT) of 3 days, led to a COD removal efficiency between 66 and 97 %, while the particulate matter of the wastewater was effectively removed by entrapment in the sludge blanket of the reactor. When the anaerobic reactor effluent was post-treated over a boron-doped diamond (BDD) anode at 9 and 18 A and in the presence of NaCl as the supporting electrolyte, complete removal of COD was attained after 3–4 h of reaction. During electrochemical experiments, three groups of organochlorinated compounds, namely trihalomethanes (THMs), haloacetonitriles (HANs), and haloketons (HKs), as well as 1,2-dichloroethane (DCA) and chloropicrin were identified as by-products of the process; these, alongside free chlorine, are thought to increase the matrix ecotoxicity to Artemia salina.

The aim of this study was to develop a laboratory-scale anaerobic dynamic membrane bioreactor (AnDMBR) for the treatment of high-strength synthetic and real cheese whey wastewater. We determined the appropriate pore size for a convenient type of support material (nylon mesh) to optimize cake layer formation. The performance of the AnDMBRs was measured in terms of chemical oxygen demand (COD) and solids removal efficiencies. During high-strength synthetic wastewater treatment, the 70-μm pore size AnDMBR achieved COD removal efficiencies of 78% and 96% with COD loading rates of 4.03 and 2.34 kg m⁻³ day⁻¹, respectively, while the 10-μm pore size AnDMBR achieved 66% and 92% COD removal efficiencies at COD loading rates of 5.02 and 3.16 kg m⁻³ day⁻¹. The 10 μm pore size AnDMBR was operated in two periods: first period and second period (before and after physical cleaning) during high-strength synthetic wastewater treatment. The 10-μm pore size AnDMBR removed 83% and 88% of suspended solids during period 1 and period 2, respectively. Furthermore, using a pore size of 10 μm retained 72% of solids (973 mg L⁻¹) in the reactor outlet. The 10-μm pore size AnDMBR performed better than the 70-μm pore size AnDMBR in terms of cake layer formation. The 10-μm pore size AnDMBR was used to treat real cheese whey wastewater, resulting in COD removal efficiencies ranging from 59% (4.32 kg m⁻³ day⁻¹) to 97% (5.22 kg m⁻³ day⁻¹). In addition, 85% of suspended solids were removed from real cheese whey wastewater after treatment. The results show that dynamic membrane technology using a pore size of 10 μm can be used to treat real industrial wastewater.

A mixed cyanobacterial-mixotrophic algal population, dominated by the filamentous cyanobacterium Leptolyngbya sp. and the microalga Ochromonas (which contributed to the total photosynthetic population with rates of less than 5%), was studied under non-aseptic conditions for its efficiency to remove organic and inorganic compounds from different types of wastes/wastewaters while simultaneously producing lipids. Second cheese whey, poplar sawdust, and grass hydrolysates were used in lab-scale experiments, in photobioreactors that operated under aerobic conditions with different initial nutrient (C, N and P) concentrations. Nutrient removal rates, biomass productivity, and the maximum oil production rates were determined. The highest lipid production was achieved using the biologically treated dairy effluent (up to 14.8% oil in dry biomass corresponding to 124 mg L⁻¹) which also led to high nutrient removal rates (up to 94%). Lipids synthesized by the microbial consortium contained high percentages of saturated and mono-unsaturated fatty acids (up to 75% in total lipids) for all the substrates tested, which implies that the produced biomass may be harnessed as a source of biodiesel.