Ocena razgradnje odpadnega blata s kavitacijo

Pomberg, Katja (author), Dular, Matevž (mentor)

Naraščajoča količina raznovrstnih odpadkov v okolju je ena resnejših težav, s katerimi se sooča človeštvo. Enega izmed glavnih virov onesnaževanja okolja z različnimi mikropolutanti predstavljajo odpadne vode in odpadno blato, katerih čiščenje predstavlja velik izziv za čistilne naprave. Odpadno blato je končen produkt procesa čiščenja odpadne vode, ki ga je potrebno primerno odstraniti. Zaradi vsebnosti raznih mikropolutantov je potrebno pred odlaganjem odpadno blato primerno obdelati – s stabilizacijo, dehidracijo in zgoščevanjem. Za zmanjševanje količine odpadnega blata je uporabna anaerobna razgradnja, vendar ta proces potrebuje veliko nadgradnje, da se doseže njegov potencial. Da bi izboljšali procese anaerobne razgradnje, je potrebno izvajati predhodne procese obdelave odpadnega blata, ki izboljšajo njegovo razgradnjo. Kot predhodni procesi obdelave odpadnega blata se lahko uporabljajo mehanski procesi, med katere spada tudi kavitacija. V magistrskem delu smo se osredotočili na predhodno obdelavo odpadnega blata s pomočjo hidrodinamične kavitacije. Kavitacija povzroča nenadno znižanje tlaka v tekočini, kar sproži nastajanje parnih in plinastih mehurčkov znotraj tekočine. Znižanje tlaka v tekočini lahko dosežemo s pomočjo rotorja in statorja, tako nastalo kavitacijo pa imenujemo hidrodinamična kavitacija. Posledica kavitacije je homoliza vode, rezultat katere so hidroksilni radikali (•OH), ki vodijo kemijske procese. Kavitacija za predhodno obdelavo odpadnega blata se uporablja za pospešitev anaerobne razgradnje, kar pripomore k večji proizvodnji bioplina, zmanjševanju količine blata, zmanjševanju količine patogenih organizmov in odstranjevanju neprijetnih vonjav. Prednost hidrodinamične kavitacije pred ostalimi procesi so nizki stroški obratovanja in boljše možnosti scale-up-a. Namen raziskovalnega dela je bil primerjati štiri različne kavitacijske režime in določiti kateri je najučinkovitejši za dezintegracijo odpadnega blata. Za predobdelavo vzorca odpadnega blata smo uporabili rotacijski generator hidrodinamične kavitacije na laboratorijskem nivoju v izvedbi z valjčki in zobmi. Učinovitost kavitacijskih režimov smo primerjali glede na spremembe kemijskih parametrov (tKPK, topnega NH4-N in NO3-N) pred in po kavitaciji s pomočjo spektroskopske metode, stopnjo razgradnje blata ter energetsko učinkovitost. Najboljšo razgradnjo aktivnega blata smo dosegli pri režimu z valjčnim rotorjem.

• Language: Slovenian
• Keywords: odpadno blato, dezintegracija, hidrodinamična kavitacija, čistilna naprava
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: FKKT - Faculty of Chemistry and Chemical Technology
• Year: 2022
• PID: 20.500.12556/RUL-141444
• COBISS.SI-ID: 132952579
• Publication date in RUL: 29.09.2022

POMBERG, Katja, 2022, Ocena razgradnje odpadnega blata s kavitacijo [online]. Master’s thesis. [Accessed 30 March 2025]. Retrieved from: https://repozitorij.uni-lj.si/IzpisGradiva.php?lang=eng&id=141444

Secondary language

• Language: English
• Title: Evaluation of waste sludge disintegration using cavitation

Abstract

The growing amount of various wastes in the environment is one of the major problems facing humanity. One of the major sources of environmental pollution with various micropollutants are wastewater and waste activated sludge (WAS). Their treatment presents a big challenge for wastewater treatment plants. Sludge is the final product of wastewater treatment process and the proper disposal of sludge is crucial. Due to the presence of various micropollutants, it is necessary to properly process the WAS before disposal – stabilization, dehydration, thickening. Anaerobic decomposition is useful for reducing the amount of waste sludge. However, the process needs a major upgrade to reach its full potential. To improve anaerobic digestion, pre-treatments of waste sludge are often used. These processes improve the disintegration and solubilization of WAS. Mechanical pre-treatment processes such as cavitation are often used for this purpose. In my master’s thesis we focused on the pre-treatment of WAS with hydrodynamic cavitation. Cavitation causes a sudden drop in pressure in a liquid, which triggers the formation of vapour and gas bubbles within the liquid. The reduction of pressure in the liquid can be achieved with the help of the rotor and stator and the resulting cavitation is called hydrodynamic cavitation. The result of cavitation is the homolysis of water molecules, which results in hydroxyl radical (•OH) that drive chemical processes. The use of cavitation for sludge pre-treatment promotes anaerobic digestion, which helps to increase biogas production, reduces the amount of sludge, reduces the amount of pathogenic organisms and removes unpleasant odours. The advantage of hydrodynamic cavitation over other processes is lower operational costs and better scaling possibilities. The purpose of the research work was to compare four different cavitation regimes and determine which one is the most effective for the disintegration of WAS. For the pre-treatment of WAS we used a rotational generator of hydrodynamic cavitation at the laboratory scale with pined and serrated disc. The effectiveness of the cavitation regimes was compared with respect to changes in chemical parameters (sCOD, soluble NH4-N and NO3-N) before and after cavitation using the spectroscopic method, disintegration degree and energy efficiency. The best disintegration of WAS was achieved with regime with pined disc.

• Keywords: waste sludge, disintegration, hydrodynamic cavitation, wastewater treatment plant