Comparative Kinetic Study of Carrier Type in a Moving Bed System Applied to Organic Matter Removal in Urban Wastewater Treatment

In recent years, moving bed systems have been shown as an efficient technology in wastewater treatment and particularly in the treatment of urban effluents. This paper presents the results obtained for three different carriers in organic matter removal, analysing the influence of hydraulic retention time (HRT) and the filling ratio, as well as the kinetic constants of each carrier used. During the research, differences in the organic matter removal were observed under different conditions studied as a result of physical and geometrical characteristics of each carrier and their hydraulic behaviour. Two of the three carriers studied in this research had similar yields compared to the third carrier that presented lower rates of organic matter removal and lower kinetic constants than the other two. Carriers 1 and 2 obtained removal rates of organic matter in the form of soluble chemical oxygen demand (sCOD) above 50% for intermediate and higher filling ratios with HRTs of 15, 10 and 15 h, respectively. The maximum values obtained for carrier 1, 2 and 3 were 56.97%, 58.92% and 46.13%, respectively, under 15 h of HRT and 50% of filling ratio. The kinetic constants obtained by respirometry showed a similar trend to the values obtained from sCOD removal.     

Comparison of Activated Sludge Technologies by Particle Size Analysis

This paper analyses the influence of activated sludge technologies on the Particle Size Distribution (PSD) of urban wastewater treatment plants operating under real conditions. The activated sludge treatment systems selected for the analysis are the most widely used in wastewater treatment installations: (a) double step activated sludge, (b) medium load activated sludge, (c) prolonged aeration, and (d) membrane bioreactors The main quality parameters (suspended solids, turbidity, and COD) and PSD in the influent and effluent of each different activated sludge treatment were analyzed during 1?year. The PSD was fitted using the power law ( $ n\left( {{d_{\text{P}}}} \right) = \frac{{\partial {\text{N}}\left( {{d_{\text{p}}}} \right)}}{{\partial {d_{\text{p}}}}} = A \cdot d_{\text{p}}^{{ - b \cdot {\text{Log}}\left( {{d_{\text{p}}}} \right)}} $ ) obtaining coefficients A and b to define the particle distribution. Mathematical correlations between this coefficients and the rest of parameters studied were found $ \left( {\matrix{ {{\text{SS}} = {0}{.0126} \cdot {A^{{{0}{.781}}}},} &{{\text{Turbidity}} = 15.5814 + 1.164 \cdot {{10}^3} \cdot A{,}} &{{\text{COD}} = \frac{{1}}{{{0}{.0133} + \cdot \frac{{{49}{.85}}}{\text{A}}}}} \\ }<!end array> } \right) $ . The relation with the average particle size by mass was also found, ( $ {d_{\text{pma}}} = - 11.6502 + \frac{{50.4265}}{b} $ ). Moreover, a relation between PSD and the particle elimination efficiency of the secondary treatment was study, ( $ \eta = 0.1434 - \frac{{0.5602}}{{{A_{\text{rel}}}}} + \frac{{0.7490}}{{{b_{\text{rel}}}}} $ ). Finally, the particulate matter nature was assessed by SEM-EDX. It can be concluded that membrane bioreactor is the technology that produces the best water quality effluent due to physic process of particle separation by ultrafiltration membrane technology.     

Mycorrhizal,nutritional and virgin olive oil parameters affected by groundcovers

Management of olive groves faces the challenge of reconciling yield, soil degradation and virgin olive oil (VOO) quality. We evaluated the effect of replacing tillage management by vegetal groundcovers (GC) on the relationships between mycorrhizal symbiosis, olive nutritional status, and VOO quality under field rainfed conditions. The experiment was set up in 2014 in an existing Cornicabra olive orchard with a Haplic Gypsisol soil under a Mediterranean semiarid climate. Four treatments were replicated four times and consisted of: (1) annual cover of bitter vetch, (2) permanent Brachypodium distachyon, (3) spontaneous vegetation cover (mainly Brassicaceae species), and (4) tilled soil. The use of bitter vetch GC increased the olive root colonization by 50% compared with the tillage treatment. The effect of tillage on VOO differed from that of GC use. Tillage treatment decreased maturity index and its VOO had lower polyphenol content and less luminosity than that from the GC treatments. Olive root colonization, together with changes in nutrients such as Cu, B and other elements resulting from GC use, seems to play an important role in explaining the variability of VOO quality parameters. Although tillage may lead to higher yield by controlling competition for water and nutrients, the introduction of GC in olive groves led to higher polyphenol contents, enhancing VOO quality and, at the same time, protecting soil from erosion.     

The Chemical Composition of Precipitation in Madrid

The present study examines the chemical characteristics of first-fraction precipitation samples collected over a period of one year in Madrid, and patterns of temporal and spatial variation observed in their composition. One hundred and sixty-four samples of wet precipitation collected on an event basis were analysed for anions, cations, pH and electrical conductivity. Precipitation in Madrid was neutral, with only 3% of samples showing pH < 5.6. Dominant ions were calcium andsulphates. Calcium was the principal neutralizing agent, explaining 64% of all nitrates and sulphates. The marine influence did not appear to be relevant, while the soil seemed to play an important role in the composition of precipitation. Precipitation chemistry displayed seasonal differences, with higher concentrations of sulphates and chloride in autumn and winter and of calcium and sodium in the summer. There was an inverse relationship between concentrations and sample volumes; while the correlation between concentrations and the time elapsedsince the last rain event was positive, though poor for normalized concentrations. Four variables (sample volume, days elapsed since the last rain event, maximum wind gust direction and season) explained to a large extent (more than 90% for some sampling stations) the variability of certain chemical variables.     

Cover crop identity determines root fungal community and arbuscular mycorrhiza colonization in following main crops

Cover crops (CC) can promote nutrient retention and recycling for main crops yet may also promote soilborne pathogens or suppress beneficial root symbionts such as arbuscular mycorrhizal fungi (AMF). We investigated how root fungal communities of main crop are affected by preceding CC monocultures and mixtures and by main crop identity. We expected that AMF abundance and diversity in main crops are promoted by AM-host CC, and suppressed by non-AM-host CC, and that mixtures of CC species can promote beneficial and suppress pathogenic root fungi. Our full-factorial field experiment comprised crop rotation in sand soil with different CC treatments (monocultures of radish [AM non-host], ryegrass, clover, vetch [AM hosts], mixtures of radish + vetch, ryegrass + clover and fallow) and two main crops (oat and endive). At peak crop growth, we investigated the root fungal communities in the main crops using microscopy and high throughput sequencing (Illumina MiSeq). Cover crop identity was of prime importance and CC legacy overruled main crop identity in determining root fungal communities in main crops. Compared with fallow, CC with ryegrass increased AMF colonization and richness in both main crops and of non-AMF in oat. Legacies of ryegrass, ryegrass + clover and vetch resulted in distinct root fungal communities in the main crops, while the legacy of CC with radish were similar to the legacy of fallow. Root fungal community in crops after clover had highest abundance of representative fungal pathogens in contrast with the other CC treatments that resulted in fungal communities where pathogens were scarce. Oppositely to expected, CC mixtures did not enhance fungal symbionts or suppressed pathogens. Overall, fungal communities in roots of the main crops in our field experiment were determined by the preceding CC species in monoculture, rather than by the CC AMF preference or functional group. This research highlights that the choice of CC determines the root fungal community in main crop which may influence crop quality.     

The Influence of Biofilm Treatment Systems on Particle Size Distribution in Three Wastewater Treatment Plants

This article presents the results of a research study that analyzed the effect that secondary biofilm treatment systems had on particle size distribution (PSD) in the effluent of wastewater treatment plants. This study focused on three biofilm technologies (i.e. a submerged biofilter system, a trickling filter system, and a rotating biological contactor system) in three working urban wastewater treatment plants. For this purpose, the variation of the fit parameters was analyzed after modeling the PSD with the power law. The greatest reduction in particle number was obtained with the submerged biofilter system, followed by the trickling filter system. In contrast, the rotating biological contactor showed the smallest reduction in particle number under the conditions of our study. It was also found that the variation of the fit parameters of the PSD, caused by the wastewater treatments was related to other wastewater parameters, such as the chemical oxygen demand, suspended solids, and the mean particle size. This showed a direct relation between these parameters and the particles in wastewater.     

Enrichment of Artemia nauplii in PUFA, phospholipids, and water-soluble nutrients using liposomes

Different liposome formulations, includingseveral combinations of membrane composition,type of vesicle (multilamellar and largeunilamellar vesicles), preparation method, andvehiculated nutrient, have been assayed asbioencapsulation products to enrich Artemia nauplii with nutrients for feeding fish larvae.The stability of the liposome preparationsunder conditions of use as enrichment producthas been tested using water soluble fluorescentmarkers as leakage indicators. The content ofthe fatty acids and lipid classesbioencapsulated in Artemia nauplii withliposomes has been analyzed by gas and thinlayer chromatography, respectively, andcompared with other enrichment products. Theeffect of the liposome enriched Artemianauplii used as food for fish larvae has beenevaluated in sea bass cultures. Liposomes withhigh content in polyunsaturated fatty acidsleak out more than 50% of their aqueous phasein less than 2 hours, unless they arestabilized with cholesterol and formed as largeunilamellar vesicles. Such vesicles hold70% of the encapsulated material for 8 hours.Liposome enriched nauplii in this study reflectthe influence of the enrichment products,however, they are far from the commercialemulsion (Super Selco) in terms ofdocosahexaenoic acid content, except for thenauplii enriched with liposomes made of purekrill phospholipid extract by the method ofdetergent solubilization. The liposome enrichednauplii show a higher amount of polar lipids incontrast to the feed enriched with emulsions.The larvae fed liposome enriched nauplii haveonly a slightly lower docosahexaenoic acidcontent than those fed emulsion enrichednauplii. The results obtained confirm thesuitable potential use of liposomes as foodsupplement in larviculture. Problems andadvantages are discussed.     

Effects of nauplial density, product concentration and product dosage on the survival of the nauplii and EFA incorporation during Artemia enrichment with liposomes

In order to determine an optimal enrichment protocol with krill phospholipid liposomes, three different experiments were carried out to evaluate the effects of nauplial density, the concentration of liposome, and the number of doses delivered to the nauplii on the survival and the essential fatty acid (EFA) bioencapsulation in Artemia nauplii. No survival differences were found between the different liposome treatments and the control nauplii enriched with a commercial emulsion. This result confirms that previously described mortalities during Artemia enrichment with liposomes can be minimized and controlled. On the other hand, the EFA incorporation obtained from the three experiments indicates that maximal bioencapsulation is achieved when incubations are carried out under nauplial densities of 300 nauplii ml^− 1, where liposomes are dispensed in a single dose at the beginning of the incubation yielding a concentration of 0.5 g l^− 1. These findings complete those obtained in two preliminary studies, and propose a well defined enrichment protocol with krill liposomes as an alternative complementary method to improve the nutritional value of the Artemia nauplii used as food for marine fish larvae.     

Effect of different dietary levels of docosahexaenoic acid (DHA, 22:6w-3) on the DHA composition of lipid classes in sea bass larvae eyes

The effect of different dietary levels of docosahexaenoic acid (DHA, 22:6w-3) on the corresponding composition of lipid classes of the eyes of sea bass, Dicentraxrchus labrax, larvae was studied using Artemia nauplii enriched with different products: oil emulsions, liposomes, a dry microalga and baker's yeast. DHA was found to be a major constituent of phosphatidylserine and phosphatidylethanolamine of visual tissues. The different DHA dietary levels were markedly reflected in the fatty acid composition of the lipid classes of eyes, suggesting a dose-dependent relationship between DHA in the food and in visual tissue lipids of sea bass larvae. The possible implications of this dietary effect are discussed.