Cultivation of microalgae in the solution from the desalting process of soy sauce waste treatment and utilization of the algal biomass for ethanol fermentation

The growth of four marine microalgae was examined in a medium prepared from the effluent from the desalting process of soy sauce waste. A strain of Dunaliella that showed abundant growth on soy sauce waste extract was selected, and optimum cultivation conditions were determined. The algal cells produced were disrupted, and saccharified with glucoamylase. The saccharified solution was fermented using Saccharomyces cerevisiae IAM 4140. Stoichiometric study revealed that 11mg of ethanol was produced from 1g (dry cell weight) of Dunaliella cells. This work indicates a new method for removing waste products of the soy sauce production industry.     

Heterotrophic cultivation of microalgae for pigment production: A review

Pigments (mainly carotenoids) are important nutraceuticals known for their potent anti-oxidant activities and have been used extensively as high end health supplements. Microalgae are the most promising sources of natural carotenoids and are devoid of the toxic effects associated with synthetic derivatives. Compared to photoautotrophic cultivation, heterotrophic cultivation of microalgae in well-controlled bioreactors for pigments production has attracted much attention for commercial applications due to overcoming the difficulties associated with the supply of CO₂ and light, as well as avoiding the contamination problems and land requirements in open autotrophic culture systems. In this review, the heterotrophic metabolic potential of microalgae and their uses in pigment production are comprehensively described. Strategies to enhance pigment production under heterotrophic conditions are critically discussed and the challenges faced in heterotrophic pigment production with possible alternative solutions are presented.     

Co-digestion of different waste mixtures from agro-industrial activities: kinetic evaluation and synergetic effects

Several wastes from agro-industrial activities were mixed in different ratios to evaluate the co-digestion process. Methane yield (Y_CH4), specific methanogenic activity (SMA) and a kinetic parameter (k₀) were determined. A second feeding was also performed to examine the recovery of bacterial activity after exhaustion.Mixture ratios of 1:1:1:1 and 1:3:4:0.5 (w/w) showed the best performance, with Y_CH4 of 664; 582 NmL CH₄/gVS_substrate, as well as SMA of 0.12; 0.13 gCOD_NmLCH4/gVS_inoculum/d, respectively, during the digestion of the first feed. It was possible to relate synergetic effects with enhancement in Y_CH4 by up to 43%, compared with values calculated from Y_CH4 of the individual substrates. All batches started up the biogas production after an exhaustion period, when a second feed was added. However, long lag phases (up to 21 days) were observed due to stressed conditions caused by the substrate limitation prior to the second feed.     

Systematic investigation of biomass and lipid productivity by microalgae in photobioreactors for biodiesel application

We describe a methodology to investigate the potential of given microalgae species for biodiesel production by characterizing their productivity in terms of both biomass and lipids. A multi-step approach was used: determination of biological needs for macronutrients (nitrate, phosphate and sulphate), determination of maximum biomass productivity (the “light-limited” regime), scaling-up of biomass production in photobioreactors, including a theoretical framework to predict corresponding productivities, and investigation of how nitrate starvation protocol affects cell biochemical composition and triggers triacylglycerol (TAG) accumulation. The methodology was applied to two freshwater strains, Chlorella vulgaris and Neochloris oleoabundans, and one seawater diatom strain, Cylindrotheca closterium. The highest total lipid content was achieved with N. oleoabundans (25-37% of DW), while the highest TAG content was found in C. vulgaris (11-14% of DW). These two species showed similar TAG productivities.     

Massive cultivation of microalgae: Results and prospects

An account is given of the development of the utilization of microalgae for food and feed with special emphasis on the advantages of algal technologies for tropical and subtropical countries. The present status of microalgae mass production is characterized with respect to technology, product properties, yields, nutrition, toxicology and economics. As a multipurpose operation, the treatment of liquid wastes with algae-bacteria systems is the most promising microalgal technology. It yields proteinaceous microbial biomass as a comparatively inexpensive by-product of the operation of high-rate algal ponds, either at the simplified rural level or at the technically more elaborate industrial level. The aspect of hard-currency saving by employing algae-bacteria systems in sewage treatment for animal feed production is stressed.     

Efficiency of ammonia and phosphorus removal from a colombian agroindustrial wastewater by the microalgae Chlorella vulgaris and Scenedesmus dimorphus

The ammonia and phosphorus removal efficiencies of the microalgae Chlorella vulgaris and Scenedesmus dimorphus, during biotreatment of secondary effluent from an agroindustrial wastewater of a dairy industry and pig farming, were evaluated. The microalgae were isolated from a wastewater stabilization pond near Santafé de Bogotá, Colombia. Batch cultures were made using both species in 4-1 cylindrical glass bioreactors each containing 2l of culture. Chlorella vulgaris was also cultivated on wastewater in a triangular bioreactor. Three 216-h experimental cycles were run for each microalga and in each bioreactor. In the cylindrical bioreactor, S. dimorphus was more efficient in removing ammonia than C. vulgaris. However, the final efficiency of both microalgae at the end of each cycle was similar. Both microalgae removed phosphorus from the wastewater to the same extent in a cylindrical bioreactor. Using C. vulgaris, the triangular bioreactor was superior for removing ammonia and the cylindrical bioreactor was superior for removing phosphorus. This study shows the potential of using these microalgae to reduce the environmental pollution of heavily contaminated agroindustrial waters currently disposed of untreated into the waterways and streams of tropical Colombia.     

Simultaneous flue gas bioremediation and reduction of microalgal biomass production costs

A flue gas originating from a municipal waste incinerator was used as a source of CO₂ for the cultivation of the microalga Chlorella vulgaris, in order to decrease the biomass production costs and to bioremediate CO₂ simultaneously. The utilization of the flue gas containing 10–13% (v/v) CO₂ and 8–10% (v/v) O₂ for the photobioreactor agitation and CO₂ supply was proven to be convenient. The growth rate of algal cultures on the flue gas was even higher when compared with the control culture supplied by a mixture of pure CO₂ and air (11% (v/v) CO₂). Correspondingly, the CO₂ fixation rate was also higher when using the flue gas (4.4 g CO₂ l⁻¹ 24 h⁻¹) than using the control gas (3.0 g CO₂ l⁻¹ 24 h⁻¹). The toxicological analysis of the biomass produced using untreated flue gas showed only a slight excess of mercury while all the other compounds (other heavy metals, polycyclic aromatic hydrocarbons, polychlorinated dibenzodioxins and dibenzofurans, and polychlorinated biphenyls) were below the limits required by the European Union foodstuff legislation. Fortunately, extending the flue gas treatment prior to the cultivation unit by a simple granulated activated carbon column led to an efficient absorption of gaseous mercury and to the algal biomass composition compliant with all the foodstuff legislation requirements.     

Anaerobic co-digestion of food waste and piggery wastewater: focusing on the role of trace elements

The objective of this study was to evaluate the feasibility of anaerobic co-digestion of food waste and piggery wastewater, and to identify the key factors governing the co-digestion performance. The analytical results indicated that the food waste contained higher energy potential and lower concentrations of trace elements than the piggery wastewater. Anaerobic co-digestion showed a significantly improved biogas productivity and process stability. The results of co-digestion of the food waste with the different fractions of the piggery wastewater suggested that trace element might be the reason for enhancing the co-digestion performance. By supplementing the trace elements, a long-term anaerobic digestion of the food waste only resulted in a high methane yield of 0.396 m³/kg VS_added and 75.6% of VS destruction with no significant volatile fatty acid accumulation. These results suggested that the typical Korean food waste was deficient with some trace elements required for anaerobic digestion.     

Survival of E. coli O157:H7 in organic wastes destined for land application

AIM: To determine the persistence of Escherichia coli O157 in contrasting organic wastes spread to land and to assess the potential environmental risk associated with the disposal of these wastes to land. METHODS AND RESULTS: Twenty-seven organic wastes originating from slaughterhouses, wastewater treatment plants (raw and treated sewage), creameries and farms (bovine slurry), were inoculated with E. coli O157:H7 and incubated at 10 degrees C. Although pathogen numbers gradually declined in all the wastes, albeit at different rates even in the same waste type, E. coli O157:H7 was still viable in 77% of organic wastes tested after 2 months. CONCLUSIONS: Long-term storage of organic wastes led to a significant and gradual decline in E. coli O157:H7 numbers. Consequently, storage may be a useful means of reducing the pathogen load of wastes destined for land application. However, in most cases, long-term storage cannot be expected to completely eliminate E. coli O157:H7 from waste. SIGNIFICANCE AND IMPACT OF THE STUDY: Our results indicate that current legislation may be insufficient to protect the environment from E. coli O157:H7 contamination from untreated wastes spread to land.     

Assessment of a dry and a wet route for the production of biofuels from microalgae: energy balance analysis

In this study, the energy balance of two microalgae-to-biofuel concepts, one via a so called “dry route” (oil extraction from dried algae) and one via a “wet route” (oil extraction in the water phase), are assessed. Both routes are intended to convert the chemical energy contained in the microalgae into high-value biofuels with minimal fossil energy consumption. The analysis shows that the drying process in the dry route and the oil extraction process in the wet route consume a significant amount of energy. By coupling waste heat from a nearby power plant to the process, the energy balance can be improved and a potential fossil energy ratio (FER) up to 2.38 and 1.82 can be reached for the dry and wet route, respectively. The results indicate that based on current available technologies, the dry route has higher FER and the wet route has more potential in producing high valuable biofuels.     

Soil microalgae and cyanobacteria: the biotechnological potential in the maintenance of soil fertility and health

Abstract

The soil microbiota plays a major role in maintaining the nutrient balance, carbon sink, and soil health. Numerous studies reported on the function of microbiota such as plant growth-promoting bacteria and fungi in soil. Although microalgae and cyanobacteria are ubiquitous in soil, very less attention has been paid on the potential of these microorganisms. The indiscriminate use of various chemicals to enhance agricultural productivity led to serious consequences like structure instability, accumulation of toxic contaminants, etc., leading to an ecological imbalance between soil, plant, and microbiota. However, the significant role of microalgae and cyanobacteria in crop productivity and other potential options has been so far undermined. The intent of the present critical review is to highlight the significance of this unique group of microorganisms in terms of maintaining soil fertility and soil health. Beneficial soil ecological applications of these two groups in enhancing plant growth, establishing interrelationships among other microbes, and detoxifying chemical agents such as insecticides, herbicides, etc. through mutualistic cooperation by synthesizing enzymes and phytohormones are presented. Since recombinant technology involving genomic integration favors the development of useful traits in microalgae and cyanobacteria for their potential application in improvement of soil fertility and health, the merits and demerits of various such advanced methodologies associated in harnessing the biotechnological potential of these photosynthetic microorganisms for sustainable agriculture were also discussed.     

Statistical evaluation and modeling of cheap substrate-based cultivation medium of Chlorella vulgaris to enhance microalgae lipid as new potential feedstock for biolubricant

Chlorella vulgaris (C. vulgaris) microalga was investigated as a new potential feedstock for the production of biodegradable lubricant. In order to enhance microalgae lipid for biolubricant production, mixotrophic growth of C. vulgaris was optimized using statistical analysis of Plackett–Burman (P-B) and response surface methodology (RSM). A cheap substrate-based medium of molasses and corn steep liquor (CSL) was used instead of expensive mineral salts to reduce the total cost of microalgae production. The effects of molasses and CSL concentration (cheap substrates) and light intensity on the growth of microalgae and their lipid content were analyzed and modeled. Designed models by RSM showed good compatibility with a 95% confidence level when compared to the cultivation system. According to the models, optimal cultivation conditions were obtained with biomass productivity of 0.123 g L^?1 day^?1 and lipid dry weight of 0.64 g L^?1 as 35% of dry weight of C. vulgaris. The extracted microalgae lipid presented useful fatty acid for biolubricant production with viscosities of 42.00 cSt at 40°C and 8.500 cSt at 100°C, viscosity index of 185, flash point of 185°C, and pour point of ?6°C. These properties showed that microalgae lipid could be used as potential feedstock for biolubricant production.     

Diatom artificial medium (DAM): a new artificial medium for the diatom <Emphasis Type="Italic">Haslea ostrearia</Emphasis> and other marine microalgae

Artificial media are used in physiological studies of microalgae to maintain consistent conditions from one experiment to another and these media must be adapted to the needs of the organism studied. The artificial medium, in this case named diatom artificial medium (DAM), was designed to maintain long-term cultures of Haslea ostrearia and 19 other planktonic microalgae, and to allow physiological studies related to metal metabolism. The biomass and biochemical composition of H. ostrearia grown in the DAM and in a modified Provasoli medium were compared to assess the suitability of this new artificial medium for the culture of this diatom. The DAM provided sufficient nutrients to allow H. ostrearia to grow as efficiently as in the enriched seawater medium, without negative impact on metabolism. The DAM was tested with 19 other microalgae in order to widen its potential use, and 18 of the 19 showed a good adaptation to this medium. The chemical speciation of metals (Cd, Cu, Pb, Zn) was assessed using a speciation mathematical model. The presence of EDTA resulted in the total complexation of the trace metals implying that they were present in a sole chemical species in the DAM.     

Evaluation of agro-industrial wastes as diets for culture of the fairy shrimpStreptocephalus proboscideus (Frauenfeld, 1873) (Crustacea:Branchiopoda:Anostraca)

Two micronized waste products were evaluated in a closed recirculation system for their suitability to replace a costly die of live algae in the culture of the Sudanese fairy shrimp,Streptocephalus proboscideus. The test population was kept at a density of 50 individuals 1^–1 (sex ratio:1/1). An agricultural waste product (YM20; mixture of pea and corn), and an industrial waste product (POME; Palm Oil Mill Effluent) were fed at two regimes: 0.1 and 0.2mg DW animal^–1 h^–1. The microalgaSelenastrum capricornutum, used as a reference diet at a density of 2.0±0.82 × 10⁵ cells ml^–1, proved adequate in preliminary screening experiments. The effect of the diets and feeding regimes on selected biological variables and water quality were followed by weekly observations and measurements. Results in terms of growth (=increase in length), cyst production, and mortality were more successful when animals were supplied high densities of YM20 than in all other treatments: mean brood size was 155±6 cysts with a maximum of 266. Length after 6 weeks about 2 cm while this ranged between1.4–1.7 cm for the other treatments. Weekly mortality rate was comparable under high food conditions. Mortality rate gradually increased from 5% in the first week to 15% in the last week. Water quality, especially nitriate concentration (measured as NO₂-N), was slightly better in the dry food fed than in the algae fed cultures. Present results are promising for large-scale culturing ofS. proboscideus in a cost-effective way by making use of agro-industrial waste products.     

A review of the current use of magnetic resonance imaging in pregnancy and safety implications for the fetus

This paper presents an overview of the application of and risks of exposure to Magnetic Resonance Imaging (MRI) in pregnancy. It reviews the risks to the fetus by considering the hazards in terms of the three main components of an MRI system. These are the static magnetic field, the time-varying magnetic gradient fields and the pulsed radio frequency fields. The hazards discussed are biological effects, miscarriage, heating effects and acoustic noise exposure. This paper also presents a survey of MRI sites within the United Kingdom to ascertain the extent of MRI usage in pregnancy. To validate the situation of MRI in pregnancy a survey was sent to 352 MR units throughout the United Kingdom. The questions were grouped to assess (a) maternal MRI diagnosis (b) fetal MRI and (c) work practices for pregnant MRI staff. The results showed that 91% of sites were imaging pregnant women in need of diagnosis in the second and third trimester. This paper highlights that MRI can add information for fetal central nervous system abnormalities identified by ultrasound screening, however within the UK direct fetal imaging was only performed in 8% of sites. This paper indicates the need for research to be undertaken for specific MRI clinical conditions. It also advises that risk assessment for pregnant staff working in MRI is performed, and that there is a clear need for further research into the effects of MRI in pregnancy as there is a need for clear authoritive advice.     

Valorization of rendering industry wastes and co-products for industrial chemicals,materials and energy: review

Over the past decades, strong global demand for industrial chemicals, raw materials and energy has been driven by rapid industrialization and population growth across the world. In this context, long-term environmental sustainability demands the development of sustainable strategies of resource utilization. The agricultural sector is a major source of underutilized or low-value streams that accompany the production of food and other biomass commodities. Animal agriculture in particular constitutes a substantial portion of the overall agricultural sector, with wastes being generated along the supply chain of slaughtering, handling, catering and rendering. The recent emergence of bovine spongiform encephalopathy (BSE) resulted in the elimination of most of the traditional uses of rendered animal meals such as blood meal, meat and bone meal (MBM) as animal feed with significant economic losses for the entire sector. The focus of this review is on the valorization progress achieved on converting protein feedstock into bio-based plastics, flocculants, surfactants and adhesives. The utilization of other rendering streams such as fat and ash rich biomass for the production of renewable fuels, solvents, drop-in chemicals, minerals and fertilizers is also critically reviewed.     

Agricultural reclamation of disturbed soils in a lignite mining area using municipal and coal wastes: the humus situation at the beginning of reclamation

Soils disturbed by long-term opencast mining were treated with organic waste materials for reclamation. Humic substances were extracted from waste and soil samples and analysed using pyrolysis-gas chromatography/mass spectrometry and electrofocusing. Furthermore, analytical pyrolysis permits to study all starting materials in situ. According to structural similarities, the statistical evaluation of the pyrolysis results clearly indicates three sample groups. The first group, called compost, implies the waste materials compost and composted sewage sludge. Moreover, pyrolysis revealed that coal humic substances are predominant in brown coal sludge, pure mine soils and mine soils treated with the different organic waste materials. They constitute the second group. The sewage sludge contains a high nitrogen potential, as expected, and represents the third group. Finally, pyrolysis generally showed the specific structural characteristics of humic and fulvic acids, respectively. Electrofocusing yielded for all samples a signal pattern that is typical of humic substances. However, number and ratio of the signals differ according to the special structural features of the samples. This revised version was published online in June 2006 with corrections to the Cover Date. This revised version was published online in June 2006 with corrections to the Cover Date. This revised version was published online in June 2006 with corrections to the Cover Date.     

Calculating the Sample Size in the Examination of Animals for the Presence of Residues Using Prior Information

The council of the European Economic Communities has issued a directive (86/469/EEC) for the examination of animals and fresh meat for the presence of residues of several hormones, drugs and environmental pollutants. The purpose of this paper is to compare the method used by the EEC with a Bayesian approach to calculate necessary sample size using prior information in different situations (assuming Beta-, Normal- and Gamma-distribution for the prior distribution). It has been shown that the Bayesian approach requires significantly smaller sample sizes for all levels of inspection. Furthermore, an example is given in the examination of pigs for the presence of residues of drugs in pork.     

DNA barcoding as a tool for early warning and monitoring alien duckweeds (Lemna sp.pl.): the case of Central Italy

Aquatic habitats are vulnerable to the invasion of alien species, so early warning protocols are necessary for eradication. The presence in Italy of two alien duckweeds in freshwaters has been documented: Lemna minuta, that showed high invasivity, and L. valdiviana, still confined to south Lazio. These two species may be mistaken for each other and for the domestic L. minor and L. gibba due to morphological variation. Here, we assess the applicability of DNA barcoding as a complement to morphological analysis for monitoring the spread of alien Lemna. We chose two chloroplast genome sequences for their ability to discriminate all Lemna species: the 5’ intron of the trnK gene and the matK gene. Among 48 samples of Lemna collected at 20 sites in Central Italy, 20 were identified as L. minor, 19 as L. minuta, five as L. trisulca and four as L. gibba. L. minuta was present at most sampling sites; in particular, at six locations of Lake Trasimeno, eight L. minuta samples were found. We demonstrate that DNA sequence analyses with cost-effective barcoding techniques can effectively support expert efforts in species determination for an early alert system of invasive Lemna species.     

Assessment of personal protective equipment use and occupational exposures in small industries in Jeddah: Health implications for workers

Small-scale industries account for a large proportion of jobs and play a vital role in most countries’ economic growth and prosperity. Due to the very low use of personal protective equipment (PPEs), employees are exposed to numerous physical, chemical, and accidental hazards in small-scale industries. PPEs are very effective in minimizing occupational injuries, accidents, and other hazards which otherwise result in substantial manpower and financial losses. The study objective was to assess the availability and use of PPEs as well as self-reported occupational exposures among workers in surveyed small industries in Jeddah. The study involved 102 workers from 28 small-scale industries (vehicle repair, welding, and paint). A survey was conducted to gather data of socio-demographic characteristics, self-reported occupational exposures, and frequency of PPEs used by workers. The occupational exposures (never exposed, sometimes exposed and always exposed) were reported in percentages including; noise exposure (19.6, 73.5 and 6.9%); dust/smoke exposure (9.8, 69.6 and 20.6%); vapors/fumes exposure (11.8, 60.8 and 27.5%); and direct sunlight (43.1, 56.9 and 0%), respectively. The reported use of different PPEs in descending order was; knee joints mats (50%), welding shields (50%), safety glasses (33.3%), gloves (27.5%), face masks (26.5%), safety shoes (10.8%) and earplugs/ muffs (8.8%). On the basis of this study findings, hand hygiene and general OSH awareness like interventions can be developed which will help in minimizing workplace exposures among small-scale industry workers.