Search results for "Fluent"

Modeling the decay of nitrite oxidizing bacteria under different reduction potential conditions

2018

[EN] Autotrophic growth and decay rates of ammonium and nitrite oxidizing bacteria (AOB and NOB, respectively) have a significant impact on the design and on the process performance of wastewater treatment systems where nitrification occurs. Literature data on the separate decay rates of AOB and NOB is scarce and inconsistent. In this study, batch experiments based on respirometric techniques were conducted to determine the NOB decay rates under different oxidation-reduction potential conditions, in order to widen the understanding of nitrite dynamics. The decay rate measured under anoxic conditions was 85% lower than under aerobic conditions, whereas under anaerobic conditions the decay ra…

PROGETTAZIONE DI UNA OPERA DI PRESA A BASSO IMPATTO AMBIENTALE PER UN IMPIANTO MINI IDROELETTRICO IN SICILIA

2013

Optical method for determining optical brightener concentration in water solution

2006

The field of environmental sensors has been developing driven by the Baltic Sea environmental considerations. The authors propose the use of optical methods for developing sensitive, selective and low cost approach to address water media emitted matter research. An optical method to detect the human anthropogenic load presence in water bodies by measuring minute optical brighteners (OBs) concentration in water due to the laundry effluent is demonstrated. The authors propose to use OBs as a conveniently and affordably detectable optical parameter to compare the levels of human impact on the water bodies studied.

Optimum design and operation of primary sludge fermentation schemes for volatile fatty acids production.

2003

This paper presents a model-knowledge based algorithm for optimising the primary sludge fermentation process design and operation. This is a recently used method to obtain the volatile fatty acids (VFA), needed to improve biological nutrient removal processes, directly from the raw wastewater. The proposed algorithm consists in a heuristic reasoning algorithm based on the expert knowledge of the process. Only effluent VFA and the sludge blanket height (SBH) have to be set as design criteria, and the optimisation algorithm obtains the minimum return sludge and waste sludge flow rates which fulfil those design criteria. A pilot plant fed with municipal raw wastewater was operated in order to …

Management of Odontoid Cervical Fracture

2019

Fractures of the cervical odontoid process are the most common fractures of the cervical tract, accounting for one third of all cervical spine fractures. They are more frequent in elderly patients, and with the aging of the world population, their incidence and clinical and social relevance are expected to increase in the near future. The mechanisms underlying odontoid fractures differ according to patient age, with high-energy mechanisms being the causative factor frequently encountered in younger patients and low-energy trauma commonly occurring in elderly patients. Despite rising incidence and costs, there is considerable uncertainty regarding the optimal management for these fractures, …

Identifying Influential Nodes: The Overlapping Modularity Vitality Framework

2023

This paper proposes an Overlapping Modularity Vitality framework for identifying influential nodes in networks with overlapping community structures. The framework uses a generalized modularity equation and the concept of vitality to calculate the centrality of a node. We investigate three definitions of overlapping modularity and three ranking strategies prioritizing hubs, bridges, or both types of nodes. Experimental investigations involving real-world networks show that the proposed framework demonstrates the benefit of incorporating overlapping community structure information to identify critical nodes in a network.

Identification of lipophilic pollutants discharged from a Finnish pulp and paper mill.

1998

Lipophilic organic compounds originating from kraft pulping and papermaking were identified by straight gas chromatography/mass spectrometry (GC/MS) analyses. Samples analyzed included a primary clarifier effluent (PE) and a secondary clarifier effluent (SE) from the activated sludge treatment plant of a Finnish ECF-bleached (Elementally Chlorine Free) kraft pulp and paper mill. Liquid-liquid extraction composition of PE was compared with solid phase extraction (SPE) and dialysis of a semipermeable membrane device (SPMD) exposed to PE. Dichloromethane extracts of particulate material isolated from PE, sludges from both the primary and secondary clarifier, a sediment collected in the vicinit…

Dissolution of resin acids, retene and wood sterols from contaminated lake sediments.

2005

The dissolution potency of hydrophobic resin acids (RAs), retene and wood sterols from sediments was studied. These wood extractives and their metabolites are sorbed from pulp and paper mill effluents to downstream sediments. With harmful components like these, sediments can pose a hazard to the aquatic environment. Therefore, sediment elutriates with water were produced under variable conditions (agitation rate and efficiency, time), and concentrations of the dissoluted compounds were analyzed. Both naturally contaminated field sediments and artificially spiked sediments were studied. By vigorous agitation RAs can be released fast from the sediment matrix and equilibrium reached within 3 d…

Do historical sediments of pulp and paper industry contribute to the exposure of fish caged in receiving waters?

2011

Field experiments were conducted in early summer 2004 by caging brown trout (Salmo trutta m. lacustris) in Southern Lake Saimaa (SE Finland) for 10 days. Cages were positioned into two depths at four distances (5 to 17 km) from the pulp and paper mill; one set with direct contact to the sediment and other locating at the three meters' depth from the water surface. Resin acids were measured from sediment, water, and fish bile. Possible toxicities were investigated by measuring liver EROD-activity, HSP70-protein, and gene expression profiles by microarray. The concentration of resin acids in the sediment showed clear gradient along the distance from the mill, and their concentrations in water…

Expression of the Vitellogenin Gene in the Liver of Juvenile Whitefish (Coregonus lavaretus L. s.l.) Exposed to Effluents from Pulp and Paper Mills

1999

Juvenile whitefish (Coregonus lavaretus L. s.l.) were exposed by caging in the field to diluted effluents from three operating pulp, paper, and paperboard mills in Southern Lake Saimaa, Finland. The expression of the vitellogenin gene, used as a biomarker of estrogenic contamination of effluents, was measured using a Northern blotting method. Increased mRNA levels, the most specific and reliable evidence for estrogen receptor-mediated actions in vivo, were found in fish caged in the vicinity of one of three mills studied. This mill was found to discharge wood-derived compounds, such as sterols and resin acids, into Lake Saimaa in amounts considerably exceeding those from the other two mills…