Search results for "Water science"
showing 10 items of 1545 documents
Quantification of kinetic parameters for heterotrophic bacteria via respirometry in a hybrid reactor
2010
Over the last decade new technologies are emerging even more for wastewater treatment. Among the new technologies, a recent possible solution regards Moving Bed Biofilm Reactors (MBBRs) that represent an effective alternative to conventional processes. More specifically such systems consist in the introduction of plastic elements inside the aerobic reactor as carrier material for the growth of attached biomass. Recently, one of the mostly used alternatives is to couple the Moving Bed Biofilm Reactor (MBBR) process with the conventional activated sludge process, and the resulting process is usually called HMBBR (Hybrid MBBR). In the MBBR process the biofilm grows attached on small plastic el…
Aerobic moving bed biofilm reactor treating thermomechanical pulping whitewater under thermophilic conditions.
2002
The continuously operated laboratory scale Kaldnes moving bed biofilm reactor (MBBR) was used for thermophilic (55 degrees C) aerobic treatment of TMP whitewater. In the MBBR, the biomass is grown on carrier elements that move along with the water in the reactor. Inoculation with mesophilic activated sludge gave 60-65% SCOD removal from the first day onwards. During the 107 days of experiment, the 60-65% SCOD removals were achieved at organic loading rates of 2.5-3.5 kg SCODm(-3) d(-1), the highest loading rates applied during the run and HRT of 13-22h. Carbohydrates, which contributed to 50-60% of the influent SCOD. were removed by 90-95%, while less than 15% of the lignin-like material (3…
Comparison of organic peracids in wastewater treatment: Disinfection, oxidation and corrosion.
2015
The use of organic peracids in wastewater treatment is attracting increasing interest. The common beneficial features of peracids are effective anti-microbial properties, lack of harmful disinfection by-products and high oxidation power. In this study performic (PFA), peracetic (PAA) and perpropionic acids (PPA) were synthesized and compared in laboratory batch experiments for the inactivation of Escherichia coli and enterococci in tertiary wastewater, oxidation of bisphenol-A and for corrosive properties. Disinfection tests revealed PFA to be a more potent disinfectant than PAA or PPA. 1.5 mg L(-1) dose and 2 min of contact time already resulted in 3.0 log E. coli and 1.2 log enterococci r…
A method for measuring low-weight carboxylic acids from biosolid compost
2006
Concentration of low-weight carboxylic acids (LWCA) is one of the important parameters that should be taken into consideration when compost is applied as soil improver for plant cultivation, because high amounts of LWCA can be toxic to plants. The present work describes a method for analysis of LWCA in compost as a useful tool for monitoring compost quality and safety. The method was tested on compost samples of two different ages: 3 (immature) and 6 (mature) months old. Acids from compost samples were extracted at high pH, filtered, and freeze-dried. The dried sodium salts were derivatized with a sulfuric acid–methanol mixture and concentrations of 11 low-weight fatty acids (C1–C10) were a…
High-Performance Liquid Chromatographic Study on Oxidation Products of Lignin and Humic Substances
1991
We describe a convenient method of preparing samples and characterizing the mixture of degradation products obtained from alkaline cupric oxide oxidation of water samples containing lignin and humic substances. The method was applied to one unpolluted humic water sample and a total mill effluent of a kraft pulp mill. The fractions (Mr > 1000) obtained by ultrafi1tration were oxidized and the products (mixtures of degradation products) were analyzed by reversed-phase high-performance liquid chromatography (Spherisorb 5 ODS column). Acetonitrile-0.01 M phosphate buffer (pH 2) was used as the eluent in a gradient system and UV (set at 280 nm) as the detection system. Differences in the …
Recent Development in Analytical Methods for Identification of Off-Flavour Compounds
1983
The best resolution of individual off-flavour compounds is achieved by glass or quartz capillary gas chromatography. A special two-column system was used by which simultaneous instrumental detection and sniffing (odour desorption) of odorous compounds could be done. The measuring detectors were flame ionization (FID), electron capture (ECD), flame photometric (FPD) and a mass spectrometer (MS). Structural assignments of the odorous substances were done from MS data and verified by model compounds. Before the GC run the sample was collected at the head of the double column using a cold trap device. The sample for analysis was injected in liquid form or, more efficiently, thermally desorbed f…
An extension of ASM2d including pH calculation
2003
This paper presents an extension of the Activated Sludge Model No. 2d (ASM2d) including a chemical model able to calculate the pH value in biological processes. The developed chemical model incorporates the complete set of chemical species affecting the pH value to ASM2d describing non-equilibrium biochemical processes. It considers the system formed by one aqueous phase, in which biochemical processes take place, and one gaseous phase, and is based on the assumptions of instantaneous chemical equilibrium under liquid phase and kinetically governed mass transport between the liquid and gas phase. The ASM2d enlargement comprises the addition of every component affecting the pH value and an i…
Sorption of heavy metals in the biomass of alga Palmaria palmata
2013
Sorption of heavy metals by the sea alga Palmaria palmata was investigated in laboratory conditions. The sorption process of the analytes was carried out with constant flow of the solutions through the algae samples. The Langmuir isotherm model was used to describe equilibria. The experiments confirmed that 50 min of exposure of algae with little heavy metal contamination in contaminated waters results in the increase of concentration of these analytes, proportional to their concentration in the tested waters. On the basis of the Langmuir isotherm direction factor, a = (c(a,max) × K)−1, affinity of heavy metals and algae increases in the following sequence: Mn2+ < Zn2+ ≈ Cd2+ &lt…
Integrated urban water modelling with uncertainty analysis
2006
In the last twenty years, the scientific world has paid particular care towards the problems that involve the environment. Accordingly, several researches were developed to describe phenomena that take place during both wet and dry periods and to increase the knowledge in this field. In particular, attention was addressed towards the problems linked with receiving water body pollution because of the impact of rain water in the urban environment. In order to obtain a good description of the problem, it is important to analyse both quantity and quality aspects connected with all the transformation phases that characterise the urban water cycle. Today, according to this point, integrated model…
Determination of pharmaceutical residues and assessment of their removal efficiency at the Daugavgriva municipal wastewater treatment plant in Riga, …
2017
Pharmaceutical products (PPs) belong to emerging contaminants that may accumulate along with other chemical pollutants in wastewaters (WWs) entering industrial and/or urban wastewater treatment plants (WWTPs). In the present study, the technique of ultra-high-performance liquid chromatography coupled to Orbitrap high-resolution mass spectrometry (Orbitrap-HRMS) was applied for the analysis of 24 multi-class PPs in WW samples collected at different technological stages of Daugavgriva WWTP located in Riga, Latvia. Caffeine and acetaminophen levels in the range of 7,570–11,403 ng/L and 810–1,883 ng/L, respectively, were the predominant compounds among 19 PPs determined in the WW. The results i…