Andrejs Berzins

The effects of woodchip- and straw-derived biochars on the persistence of the herbicide 4-chloro-2-methylphenoxyacetic acid (MCPA) in soils.

Sorption and degradation are the primary processes controlling the efficacy and runoff contamination risk of agrochemicals. This study assessed the influence of two biochars, made from woodchips and straw at a pyrolysis temperature of 725°C and applied to a loamy sand and a sandy soil in the concentration of 5.3 g 100 g(-1) sandy soil and 4.1 g 100 g(-1) loamy sand soil, or 53 t ha(-1) for both soil types, on degradation of the herbicide 4-chloro-2-methylphenoxyacetic acid (MCPA). Soils were spiked with 50 mg MCPA kg(-1) soil. In the sandy soil, significantly more MCPA remained after 100 days if amended with straw-derived biochar in comparison to wood-derived biochar. Both biochars types significantly increased urease activity (p<0.05) after 37 days in the loamy sand soil, but these differences disappeared after 100 days. A root and shoot elongation test demonstrated that the soils containing straw-derived biochar and spiked with MCPA, showed the highest phytotoxicity. Both biochars were found to retard MCPA degradation in loamy sand and sandy soils. This effect could not be explained only by sorption processes due to comparatively low developed micro/mesoporous structure of both biochars shown by BET surface analysis. However, an enhanced MCPA persistence and soil toxicity in sandy soil amended with straw biochar was observed and further studies are needed to reveal the responsible mechanisms.

Influence of Micromixing on Microorganisms and Products

The influence of mixing intensity as well as physical and chemical parameters on the cells of different microorganisms and the biosynthesis process is examined in this paper. Some reactions of cells effecting mixing intensity are described, such as retarded biomass growth, changes in aggregation and mutual arrangement of cells, morphological changes of cells and decreasing of biological activity, caused by an increased intensity of turbulence (turbohypobiosis). Several methods for investigating the local energy in reactors are compared. It is concluded that conventional methods of hydrodynamic analysis do not always allow valid results for the optimization of the mixing regime to be obtained; practically any system requires its own optimization to achieve the maximum yield. To prevent possible adverse effects of micromixing, while simultaneously employing the positive effects the developers of a new biotechnological process should perform a whole range of experiments (for process optimization) varying temperature pH and other factors, as well as aeration and mixing intensity simultaneously with medium composition.

Removal of pharmaceuticals from municipal wastewaters at laboratory scale by treatment with activated sludge and biostimulation

Municipal wastewater containing 21 pharmaceutical compounds, as well as activated sludge obtained from the aeration tank of the same wastewater treatment plant were used in lab-scale biodegradation experiments. The concentrations of pharmaceutical compounds were determined by high-performance liquid chromatography coupled to Orbitrap high-resolution mass spectrometry and ranged from 13.2ng/L to 51.8μg/L. Activated sludge was characterized in the terms of phylogenetic and catabolic diversity of microbial community, as well as its morphology. Proteobacteria (24.0%) represented the most abundant phylum, followed by Bacteroidetes (19.8%) and Firmicutes (13.2%). Bioaugmentation of wastewater with activated sludge stimulated the biodegradation process for 14 compounds. The concentration of carbamazepine in non-amended and bioaugmented WW decreased during the first 17h up to 30% and 70%, respectively. Diclofenac and ibuprofen demonstrated comparatively slow removal. The stimulating effect of the added nutrients was observed for the degradation of almost all pharmaceuticals detected in WW. The most pronounced effect of nutrients was found for erythromycin. The results were compared with those obtained for the full-scale WW treatment process.

Excess turbulence as a cause of turbohypobiosis in cultivation of microorganisms

The present review describes the influence of different types of mixing systems under excess turbulence conditions on microorganisms. Turbohypobiosis phenomena were described by applying a method for measurement of the kinetic energy of flow fluctuations based on the piezoeffect. It can be assumed that the shear stress effect (the state of turbohypobiosis) plays a role mainly when alternative mechanisms in cells cannot ensure a normal physiological state under stress conditions. Practically any system (inner construction of a bioreactor, culture and cultivation conditions, including mixing) requires its own optimisation to achieve the final goal, namely, the maximum product and/or biomass yields from substrate (YP/S or/and YX/S), respectively. Data on the biotechnological performance of cultivation as well as power input, kinetic energy (e) of flow fluctuations, air consumption rate, rotational speed, tip speed, etc. do not correlate directly if the mixing systems (impellers-baffles) are dissimilar. Even the widely used specific power consumption cannot be relied upon for scaling up the cultivation performance using dissimilar mixing systems. A biochemical explanation for substrate and product transport via cell walls, carbon pathways, energy generation and utilisation, etc. furnishes insight into cellular interactions with turbulence of different origin for different types of microorganisms (single cells, mycelia forming cells, etc.).

Optimization of Nitrification Process by a Bacterial Consortium in the Submerged Biofiltration System with Ceramic Bead Carrier

Laboratory-scale solid phase submerged system was developed to study the process of ammonium biodegradation. Ceramic beads were found to be an appropriate carrier material for the attachment of thePNN bacterial consortium (Pseudomonas sp., Nitrosomonas sp., Nitrobacter sp.) exhibiting nitrification/denitrification activity. This consortium was previously isolated from a biological activated sludge process at a fish factory wastewater treatment plant. Three organic amendments - molasses, humic acid extract, and malt extract - were used for the ceramic bead pretreatment. Molasses significantly enhanced (p<0.05) the process of bacteria attachment onto the ceramic carrier and further ammonium removal from the bulk liquid media. The addition of 0.45% fructose to the column notably enhanced ammonium oxidation, as demonstrated by more rapid formation of nitrites in the medium when compared to the sets without sugars. The results of this study could be incorporated in a larger-scale test of a biofiltration column using wastewater from a fish processing factory.

Cultivation of Zymomonas mobilis 113 S at Different Mixing Regimes and their Influence on the Levan Formation

The Zymomonas mobilis I 13 S strain was cultivated in a bioreactor with a working volume of 1.4 I at different stirring regimes in a 15% initial sucrose medium The levan obtained in the fermentation process was analyzed by gel filtration. Because the sucrose/biomass ratio in the fermentation broth decreased to below 300 g/g, the insufficient concentration of sucrose might have decreased the concentration of levan. Besides the growth characteristics of the population, the mixing intensity and flow structure were also found to influence the molecular mass of levan. At 600 rpm, the microorganisms produced levan with a molecular mass lower than at 300 rpm. The stirring of a fermentation broth with levan without cells at 300 rpm and 900 rpm showed changes in the molecular mass approximately at 20 kD and 5 kD. The size of eddies in the fermenter was supposed to determine the size of a levan molecule. Because the size of the eddy may be compared with that of a levan molecule, it explains the decline in the molecular mass of levan.

Physicochemical Pretreatment of Contaminated Microfibre Cloths after Their Use in Waterless Car Wash / Ar virsmas aktīvām vielām piesārņotu bezūdens automašīnu tīrīšanas mikrošķiedru audumu fizikāli-ķīmiskā priekšapstrāde.

Abstract Contaminated microfibre cloths (80 % polyester and 20 % polyamide) which were previously used in waterless car cleaning process were treated in ultrasonic bath. Efficiency of water, ethanol, 2-propanol and ethylene glycol as liquid phase for ultrasonic treatment was compared. Chemical oxygen demand (COD), concentration of surfactants and total nitrogen in the extract were tested after 0 min, 10 min, 30 min and 60 min ultrasonic (US) exposure (42 kHz). In all cases the COD values gradually increased in a time dependent manner from 6 % to 35 % with ethanol, from 17 % to 37 % with ethyleneglycol and from 17 % to 33 % with 2-propanol at 10 to 60 min US mode, respectively. Bezūdens automašīnu mazgāšana pamatojas uz virsmas apstrādi ar mazgājamo līdzekli, kas satur virsmas aktīvās vielas, vaskus un citus savienojumus, kas ir biodegradējami un nav toksiski. Šī līdzekļa noslaucīšanai no automašīnu virsmas, neizmantojot ūdeni, pielieto mikrošķiedras audumu (80 % poliesters un 20 % poliamīds). Lai atkārtoti izmantotu šo audumu, pētīja tā mazgāšanas priekšapstrādes efektivitāti dažādos šķīdinātājos (ūdens, etanols, etilēnglikols un 2-propanols) pie dažādiem ultraskaņas režīmiem (42 kHz, ekspozīcijas laiks 0 min, 10 min, 30 min un 60 min). Izvērtēja dažādu šķīdinātāju efektivitāti audumu attīrīšanā no netīrumiem, tīrīšanas līdzekļa virsmas aktīvām vielām un vaskiem. Analizējamā šķīdumā noteica ķīmiskā skābekļa patēriņu (ĶSP), virsmas aktīvo vielu daudzumu, kopējā slāpekļa daudzumu (Nkop) un šķīduma duļķainību. Priekšapstrādes procesos visos gadījumos ĶSP palielinājās, palielinoties ultraskaņas ekspozīcijas laikam no 10 min līdz 60 min: etanola gadījumā no 6 % līdz 35 %, etilēnglikola gadījumā no 17 % līdz 37 % un 2-propanola gadījumā no 17 % līdz 32 %. Mikrošķiedras audumu priekšapstrāde, nepielietojot ultraskaņu, nepalielināja analizējamo šķīdumu ĶSP. Nkop un virsmas aktīvo vielu koncentrācija mikrošķiedras audumu priekšapstrādes šķīdumos (izņemot ūdeni) palielinājās, attiecīgi palielinot ultraskaņas ekspozīcijas laiku no 0 min līdz 60 min. Ultraskaņas ekspozīcijas laiks praktiski neietekmēja virsmas aktīvo vielu koncentrāciju ūdens šķīdumā un sasniedza 0,18 %. Visefektīvākais no testējamajiem priekšapstrādes variantiem bija ultraskaņas ekspozīcijas laiks 60 min 2-propanola šķīdumā. Nkop un virsmas aktīvo vielu koncentrācija analizējamā paraugā attiecīgi sasniedza 200 mg·L−1 un 0.24 %. Optimālo priekšapstrādes variantu noteikšanai, kā arī iegūto šķīdumu ar augstu ĶSP tālākai izmantošanai ir nepieciešami tālāki pētījumi.