Water purification using magnetic assistance: a review.

Sewage sludge management is now becoming a serious issue all over the world. Anaerobic digestion is a simple and well-studied process capable of biologically converting the chemical energy of sewage sludge into methane-rich biogas, as a carbon-neutral alternative to fossil fuels whilst destroying pathogens and removing odors. Hydrolysis is the rate-limiting step because of the sewage sludge complex floc structure (such as extracellular polymeric substances) and hard cell wall. To accelerate the rate-limiting hydrolysis and improve the efficiency of anaerobic digestion, various pretreatment technologies have been developed. This paper presents an up-to-date review of recent research achievements in the pretreatment technologies used for improving biogas production including mechanical (ultrasonic, microwave, electrokinetic and high-pressure homogenization), thermal, chemical (acidic, alkali, ozonation, Fenton and Fe(II)-activated persulfate oxidation), and biological options (temperature-phased anaerobic digestion and microbial electrolysis cell). The effectiveness and relative worth of each of the studied technologies are summarized and compared in terms of the resulting sludge properties, the digester performance, the environmental benefits and the current state of real-world application. The challenge and technical issues encountered during sludge cotreatment are discussed, and the future research needs in promoting full-scale implementations of those approaches are proposed.

Overview of pretreatment strategies for enhancing sewage sludge disintegration and subsequent anaerobic digestion: Current advances, full-scale application and future perspectives

A review on anaerobic biofilm reactors for the treatment of dairy industry wastewater

The use of algae as a potential substrate in biogas production processes has been discussed sporadically, therefore this manuscript provides an overview of reference data published so far on that matter. The goal of this review is to present possibilities of applying algae biomass for biogas production purposes and to determine the effectiveness of the fermentation process of algae belonging to various taxonomic groups, originating from various biocenoses and characterized by different morphology and properties. Finally, this work reports on methods and technological solutions for algae biomass production as well as impediments and opportunities stemming from algae biomass use in biogas production technologies.

Algae biomass as an alternative substrate in biogas production technologies—Review

Development of renewable energy sources market and biofuels in The European Union

The purpose of this work was to examine the settling properties of activated sludge from a sequencing batch reactor (SBR). The experiments were carried out in a bench-scale reactor, fed with wastewater from the University of Olsztyn treatment plant. Concentrations of the examined activated sludge varied between 2.5 and 6.0 kg SS m -3 . Laboratory analyses of the sludge comprised: sludge concentration, settleability, sedimentation velocity and sludge volume index (SVI). The study revealed very good settling properties of the sludge. Low SVI (30 - 60 ml g -1 SS) was responsible for an intensive and quick sedimentation which shortened the settle phase to less than one hour. Moreover, low SVI prevented the sludge from bulking. High dissolved oxygen concentrations in the aeration tank during the react phase resulted in little sludge biomass growth, which is very important from the viewpoint of sludge disposal at a wastewater treatment plant.

Settling Properties of Activated Sludge from a Sequencing Batch Reactor (SBR)

We investigated an effect of the direct impact of a constant magnetic field on wastewater properties modification. Wastewater from two sources (differing in physical and chemical properties) was used in the experiment. Analyses regarded the impact of a constant magnetic field on the properties of wastewater prepared from powdered milk and on the composition of sewage taken directly from municipal sewage system. The experiment was carried out in the laboratory scale with the use of the technological systems comprised of magnetic activators of liquids. An obvious and regular reduction was observed in COD (2555%), chlorides (25–40%), N-NH4 (50-66%), P-PO4 to the values of 3.37-6.00 mg/dm 3, and a considerable increase of Fe concentration. The parameters of both magnetically-treated wastewater types were modified to a similar degree and displayed analogous modification tendencies.

Effect of the constant magnetic field on the composition of dairy wastewater and domestic sewage

Wastewater treatment plants affect the environment in many different ways. It can be assumed that the intensity and range of microbiological emission is the crucial factor in determining the range of restrictedusage zone. This paper presents emission levels of microbiological pollutants from the wastewater treatment plant in Bartoszyce, Poland. It is a new plant with multifunctional activated-sludge tanks where wastewater is aerated by horizontal-axis aerators. The study has shown that aeration tanks constitute a significant source of biological aerosol emissions. Considerably smaller amounts of microorganisms are emitted into the atmosphere from wastewater-collection posts and secondary settling tanks.

Microbiological air pollution in the surroundings of the waste water treatment plant with activated-sludge tanks aerated by horizontal rotors

Constant magnetic field (CMF) was investigated for its potential to intensify chemical oxygen demand (COD) removal in wastewater when applied with a generalized Fenton reaction. Various types of industrial and domestic wastewater were tested in the experiment. A significant dependence was observed between the wastewater type, dose of reacting substances, time of exposure to CMF, effectiveness of COD removal, and the rate of the advanced oxidation process. The use of CMF resulted in the improvement of the treatment process; however, the efficiency depended to a great extent on the type of wastewater and characteristics of the contained organic matter. Domestic wastewater seemed to be most amenable to the applied treatment (82% COD reduction). The least reduction in COD occurred for wood industry wastewater. In the analyzed wastewater, intense oxidation was observed during the first 60 minutes of the process. Longer reaction time did not increase COD reduction, with the exception of wood industry wastewater. The experiment revealed the possibility of applying smaller doses of the Fenton's reagent, thereby keeping up unchanged treatment efficiency, provided that CMFs are applied.

Chemical oxygen demand reduction of various wastewater types using magnetic field-assisted fenton reaction.

The feasibility of magnetic field was examined as a factor affecting sludge conditioning intensification. In the experiment sludge after preliminary anaerobic digestion was used, coming from a domestic wastewater treatment plant. Digested sludge was taken directly from a fermentation tank. The experiment was run in three phases. They were performed on a laboratory scale, at various experimental stands. Different dosages of iron chloride, hydrogen peroxide and Fenton’s reagent were applied to determine their influence on the sludge properties as well as the effect of constant magnetic field on the conditioning parameters was determined. Straight dependence was found between dosage of the reagents and the way of sludge introduction in the magnetic activity zone, as well as physical and chemical parameters of the prepared sludge.

Mirosław Krzemieniewski

Papers

Settling Properties of Activated Sludge from a Sequencing Batch Reactor (SBR)

Effect of the constant magnetic field on the composition of dairy wastewater and domestic sewage

Microbiological air pollution in the surroundings of the waste water treatment plant with activated-sludge tanks aerated by horizontal rotors

Chemical oxygen demand reduction of various wastewater types using magnetic field-assisted fenton reaction.

Effect of Sludge Conditioning by Chemical Methods with Magnetic Field Application