Session 1 - Wastewater treatment

[CEST2019_00302] Printing ink wastewater treatment using electrocoagulation
by Papadopoulos K.P., Argyriou R., Ekonomou C.N., Tatoulis T.I., Tekerlekopoulou A.G., Vayenas D.V.

Packaging paper wastewaters, stemming mainly from the dyeing sector of the production process (where printing inks are utilized), are characterized by large concentrations of organic matter, deep, strong color and almost zero biodegradability factor. These attributes, in combination with the presence of some toxic compounds (heavy metals, VOCs etc.) make further treatment necessary, before releasing the wastewater to the environment.
The present study deals with the treatment of these effluents using Electrocoagulation (EC). During the EC process, metallic species are electrochemically dissolved in the wastewater solution, resulting in coagulation, flocculation and subsequent separation of the pollutants via flotation or sedimentation. The efficiency of this method was evaluated, by examining the organic matter removal and decolorization of the wastewater under a wide range of operating parameters (current density, initial pH and electrode material). Moreover, the physical and chemical phenomena taking place during the process, as well its environmental footprint were investigated.
It was observed that this process is efficient under most of the operating conditions used, as the chemical oxygen demand removal ranged between 65 and 85 % and all the experiments managed high color removal, ranging between 98 - 100%. Additionally, secondary pollution was minimized, as concentrations of soluble metallic species remained below the regulated limits.

Session: 1, Room: A, at Thu, 09/05/2019 - 10:15 to 10:30
Oral presentation in Wastewater treatment
[CEST2019_00273] The Use of Biochar from Waste Wooden Biomass for Removal of Emerging Pollutants
by Žgajnar Gotvajn A., Carvalho A.P., Marinšek M.,Kalčikova G.

The aim of presented research is to use biochar produced from waste biomass for removal of veterinary antibiotic tiamulin from model wastewater. Produced biochar was activated using different chemical methods (KOH treatment under various conditions). It was characterised using BET method for the determination of the pore size distribution and pore volume fraction as well as SEM microscopy. Results indicated importance of biochar activation to achieve applicable adsorption characteristics. In 180 minutes of batch experiment up to 78% of tiamulin was removed. Kinetic parameters were also determined by Lagergren model while for determination of adsorption isotherm Freundlich model fitted obtained data. It was concluded, that adsorption characteristics of produced and activated biochar are comparable to those of commercially available activated carbons and thus its feasibility for removal of tiamulin from model wastewater was confirmed.

Session: 1, Room: A, at Thu, 09/05/2019 - 10:00 to 10:15
Oral presentation in Wastewater treatment
[CEST2019_00251] Challenges in biological treatment plants: the approach of zero sludge waste
by Theofanidis S.A., Samiotis G., Bellos D., Pekridis G., Tsioptsias C.,Amanatidou E.

The current trend in operation of biological Wastewater Treatment Plants (WWTPs) is the minimization of sludge wastage due to its labor and cost intensive management process. Minimization of sludge can be achieved by increasing the solids retention time (SRT) in a WWTP, up to an almost complete retention of solids. This operational modification can induce problems that compromise effluent quality, such as: (a) excessive accumulation of sludge, (b) Dissolved Oxygen availability, (c) changes of C:N:P nutrient ratio, (d) changes of microbiological and morphological characteristics of biomass and (e) insufficient treatment. By imposing specific WWTP design and operational conditions, the SRT related problems can be resolved. The current study presents results based on monitoring five full scale industrial and municipal WWTPs, operating towards “complete solids retention”. The results showed that under high SRT and after the modification in the design and operation of a WWTP, successful microbial manipulation can be achieved. This leads to (i) excess sludge minimization, up to 95%, (ii) good sludge settling characteristics, with SVI < 120 ml/g, (iii) sufficient wastewater treatment, with removal efficiencies, up to 99%, 98% and 99% for COD, TN and TP respectively.

Session: 1, Room: A, at Thu, 09/05/2019 - 09:45 to 10:00
Oral presentation in Wastewater treatment
[CEST2019_00169] Phosphorus and nitrogen recovery from wastewater in the form of struvite: alternative magnesium sources
by Primikyris G., Siahos K., Vavouraki A., Putnis C.V., Natsi P.D., Koutsoukos P.G.

Recovery of phosphorus and nitrogen from municipal and other types of wastewater may be achieved through the direct crystallization of struvite (magnesium ammonium phosphate hexahydrate, Mg•NH4•PO4•6H2O). Wastewater deficiency in magnesium makes it necessary for the external addition of magnesium to make up for the supersaturation needed. In the present work we have tested artificial seawater and saturated with respect to calcined magnesia (MgO) aqueous solutions as magnesium sources, as both sources are low cost and readily available. Both the spontaneous precipitation and the seeded crystal growth have been investigated at constant supersaturation (pH 9.0- 10.0, 25°C). Seawater accelerated the precipitation of struvite and narrowed the stability domain of the supersaturated solutions. Saturated magnesia solutions were shown to broaden the stability domain of the struvite supersaturated solutions. Magnesia suspensions were also tested with respect to their ability to induce crystallization of struvite. Measurement of the kinetics of crystal growth by potentiometric methods maintaining solution supersaturation, and AFM observations showed that the solid particles in magnesia saturated suspensions, provide favorable substrate for the overgrowth of struvite in combination with the appropriate supersaturation conditions.

Session: 1, Room: A, at Thu, 09/05/2019 - 09:30 to 09:45
Oral presentation in Wastewater treatment