Thermophilic bioremediation strategies for a dairy waste

Bacterial communities in different locations, seasons and segments of a dairy wastewater treatment system consisting of six segments

A dairy wastewater treatment system composed of the 1st segment (no aeration) equipped with a facility for the destruction of milk fat particles, four successive aerobic treatment segments with activated sludge and a final sludge settlement segment was developed. The activated sludge is circulated through the six segments by settling sediments (activated sludge) in the 6th segment and sending the sediments beck to the 1st and 2nd segments. Microbiota was examined using samples from the non-aerated 1st and aerated 2nd segments obtained from two farms using the same system in summer or winter. Principal component analysis showed that the change in microbiota from the 1st to 2nd segments concomitant with effective wastewater treatment is affected by the concentrations of activated sludge and organic matter (biological oxygen demand [BOD]), and dissolved oxygen (DO) content. Microbiota from five segments (1st and four successive aerobic segments) in one location was also examined. Although the activated sludge is circulating throughout all the segments, microbiota fluctuation was observed. The observed successive changes in microbiota reflected the changes in the concentrations of organic matter and other physicochemical conditions (such as DO), suggesting that the microbiota is flexibly changeable depending on the environmental condition in the segments. The genera Dechloromonas, Zoogloea and Leptothrix are frequently observed in this wastewater treatment system throughout the analyses of microbiota in this study.

Integrated application of upflow anaerobic sludge blanket reactor for the treatment of wastewaters

The UASB process among other treatment methods has been recognized as a core method of an advanced technology for environmental protection. This paper highlights the treatment of seven types of wastewaters i.e. palm oil mill effluent (POME), distillery wastewater, slaughterhouse wastewater, piggery wastewater, dairy wastewater, fishery wastewater and municipal wastewater (black and gray) by UASB process. The purpose of this study is to explore the pollution load of these wastewaters and their treatment potential use in upflow anaerobic sludge blanket process. The general characterization of wastewater, treatment in UASB reactor with operational parameters and reactor performance in terms of COD removal and biogas production are thoroughly discussed in the paper. The concrete data illustrates the reactor configuration, thus giving maximum awareness about upflow anaerobic sludge blanket reactor for further research. The future aspects for research needs are also outlined.

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.

Thermo- and mesophilic aerobic batch biodegradation of high-strength distillery wastewater (potato stillage)--utilisation of main carbon sources

The aim of the study was to ascertain the extent to which temperature influences the utilisation of main carbon sources (reducing substances determined before and after hydrolysis, glycerol and organic acids) by a mixed culture of thermo- and mesophilic bacteria of the genus Bacillus in the course of aerobic batch biodegradation of potato stillage, a high-strength distillery effluent (COD=51.88 g O(2)/l). The experiments were performed at 20, 30, 35, 40, 45, 50, 55, 60 and 63 degrees C, at pH 7, in a 5l working volume stirred-tank bioreactor (Biostat B, B. Braun Biotech International) with a stirrer speed of 550 rpm and aeration at 1.6 vvm. Particular consideration was given to the following issues: (1) the sequence in which the main carbon sources in the stillage were assimilated and (2) the extent of their assimilation achieved under these conditions.

Isolation and selection of native microorganisms for the aerobic treatment of simulated dairy wastewaters

Milk fat/protein degrading microorganisms were isolated from different locations of a dairy wastewater treatment system with the goal of developing an inoculum for bioaugmentation strategies. Eight isolates, identified by 16S rRNA gene sequence analysis as belonging to the genera Bacillus, Pseudomonas, and Acinetobacter, were tested for their ability to remove COD and protein from a milk-based medium (3000 mg/L COD) and compared to a commercial bioaugmentation inoculum. The Acinetobacter isolate exhibited a pellet-type growth in liquid culture, a property that could potentially aid in the separation of microbes and liquid phase following treatment. Based on the individual degradation capacity and growth behavior of the isolates, three microorganisms were further selected and tested together. This consortium exhibited a COD removal similar to the commercial inoculum (57% and 63%, respectively), but higher protein (consortium: 93%; commercial inoculum: 54%), and fat removals (consortium: 75%; commercial inoculum: 38%).

Current Strategies for Dairy Waste Management: A Review

Industrial waste management is nowadays one of the main issues for ensuring a sustainable environment. Dairy waste management in particular, is very crucial in view of the high organic matter and high nutrient levels contained in dairy effluents. Dairy waste can be effectively treated either with aerobic or anaerobic processes. The main advantages of the former consist of low yield, high kinetics, pathogen free product, and high temperature operation whereas the latter is a simple, low budget and conservative technology. Occasionally, pre-treatment strategies (i.e. wetlands) are required in order to improve the efficiency of treatment methodology. Wetlands are a promising technology applied in order to remove the greater part of nutrients and minerals contained in milk based products.

The use of multi-parameter flow cytometry to study the impact of limiting substrate, agitation intensity, and dilution rate on cell aggregation during Bacillus licheniformis CCMI 1034 aerobic continuous culture fermentations

The main objective of this work was to establish those factors either physical (power input) or chemical (limiting substrate or dilution rate) that enhance cell aggregation (biofilm or floc formation) and cell physiological state during aerobic continuous cultures of Bacillus licheniformis. Glucose-limited steady-state continuous cultures growing at a dilution rate between 0.64 and 0.87/h and 1,000 rpm (mean specific energy dissipation rate (epsilonT) = 6.5 W/kg), led to the formation of a thin biofilm on the vessel wall characterized by the presence of a high proportion of healthy cells in the broth (after aggregate disruption by sonication) defined as having intact polarized cytoplasmic membranes. An increased epsilonT (from 6.5 W/kg to 38 W/kg) was found to hinder cell aggregation under carbon limitation. The carbon recovery calculated from glucose indicated that additional extracellular polymer was being produced at dilution rates >0.87/h. B. licheniformis growth under nitrogen limitation led to floc formation which increased in size with dilution rate. Counter-intuitively the flocs became more substantial with an increase in epsilonT from 6.5 W/kg to 38 W/kg under nitrogen limitation. Indeed the best culture conditions for enhanced metabolically active cell aggregate formation was under nitrogen limitation at epsilonT = 6.5 W/kg (leading to floc formation), and under carbon limitation at a dilution rate of between 0.64 and 0.87/h, at epsilonT = 6.5 W/kg (leading to vessel wall biofilm formation). This information could be used to optimize culture conditions for improved cell aggregation and hence biomass separation, during thermophilic aerobic bioremediation processes.

Acetate production from lactose by Clostridium thermolacticum and hydrogen-scavenging microorganisms in continuous culture—Effect of hydrogen partial pressure

The effect of the addition of hydrogen-consuming microorganisms on the metabolism of Clostridium thermolacticum was studied. By growing this bacterium in continuous culture at 58 degrees C, on 29 mmol lactose l(-1) (10 gl(-1)) in the feed, with the H2-consuming microorganisms Methanothermobacter thermoautotrophicus and Moorella thermoautotrophica, the volumetric productivity of acetate was increased up to 3.9 mmol l(-1)h(-1) at a dilution rate of 0.058 h(-1). This was about three times higher than the maximal acetate volumetric productivity quantified when C. thermolacticum was cultivated alone. In the consortium, C. thermolacticum was the only species able to metabolize lactose; it produced not only acetate, but also hydrogen, carbon dioxide and lactate. The other species of the consortium were growing on these by-products. Meth. thermoautotrophicus played an important role as a very efficient hydrogen scavenger and decreased the hydrogen partial pressure drastically: hydrogen was converted to methane. Moor. thermoautotrophica converted lactate as well as hydrogen and carbon dioxide into acetate. As a consequence, lactose was efficiently consumed and the only organic product in the liquid phase was acetate.