Odstranjevanje fosforja na predizdelanih malih čistilnih napravah z uporabo elektrokoagulacijskega mešala

doktorska disertacija

Ana Dragoš (Author), Nataša Atanasova (Mentor), Darko Drev (Thesis defence commission member), Andreja Žgajnar Gotvajn (Thesis defence commission member), Mihael Jožef Toman (Thesis defence commission member), Tjaša Griessler Bulc (Co-mentor)

Abstract

Večina obstoječih malih čistilnih naprav v Sloveniji dosega le drugo stopnjo čiščenja komunalne odpadne vode, četudi se nahajajo na občutljivih območjih. To pomeni, da bo treba marsikje male čistilne naprave ustrezno nadgraditi s terciarno stopnjo čiščenja s poudarkom na odstranjevanju fosforja in s tem preprečiti nadaljnjo evtrofikacijo vodnih teles. Odstranjevanje fosforja iz odpadne vode je lahko učinkovito s fizikalno-kemičnimi procesi, pri čemer po učinkovitosti izstopa proces elektrokoagulacije (EC). Učinkovitost EC za odstranjevanje fosforja iz odpadne vode je sicer že dokazana s številnimi laboratorijskimi testi, vendar je njena dejanska uporaba v čistilnih napravah, zaradi težav pri vgradnji in vzdrževanju elementov, ki omogočajo EC, relativno redka. V doktorski disertaciji zato predstavljamo uporabo procesa EC za razvoj elektrokoagulacijskega mešala (ECmešalo), ki hkrati omogoča odstranjevanje fosforja iz komunalne odpadne vode z 90% učinkovitostjo in enostavno vgradnjo v predizdelane male čistilne naprave, in sicer v saržne biološke reaktorje (SBR) za povečanje učinkovitosti njihovega delovanja. Razvoj EC-mešala smo zasnovali na laboratorijskih poskusih, kjer smo z laboratorijskim EC-mešalom dosegli učinkovitost odstranjevanja ortofosfata iz modelne in realne komunalne odpadne vode, večjo od 90 %. Na osnovi laboratorijskih poskusov smo razvili prototip EC-mešala in ga vgradili v pilotni SBR, kjer smo predhodno izvedli optimizacijo druge stopnje čiščenja odpadne vode s poudarkom na odstranjevanju amonijevega dušika kot ključnega parametra za določitev časa trajanja cikla in posameznih procesnih faz. Optimizacijo smo izvedli za (1) visoke (380%890 mg/L) koncentracije amonijevega dušika z izcedno vodo in (2) nizke (27%116 mg/L) koncentracije amonijevega dušika s komunalno odpadno vodo. V prvem primeru smo za optimalen cikel določili 12-urni in za drugega 8-urni cikel. V nadaljevanju smo prototip EC-mešala vstavili v optimiziran SBR za komunalno odpadno vodo in primerjali učinkovitost delovanja s klasičnim SBR, to je brez EC-mešala. Z rezultati smo dokazali tako 97% učinkovitost odstranjevanja fosforja iz odpadne vode za SBR z vgrajenim EC-mešalom kot tudi povečano učinkovitost za ostale parametre, to je učinkovitejše odstranjevanje suspendiranih in organskih snovi. Dokazali smo, da je EC-mešalo možno enostavno vgraditi v predizdelane ali obstoječe male čistilne naprave in s tem izboljšati njihovo delovanje. EC-mešalo je bilo tudi patentirano na Uradu RS za intelektualno lastnino, patent: SI 25287 A.

Keywords

Varstvo okolja;disertacije;elektrokoagulacija;mala čistilna naprava;fosfor;saržni biološki reaktor;

Data

Language:	Slovenian
Year of publishing:	2018
Typology:	2.08 - Doctoral Dissertation
Organization:	UL FGG - Faculty of Civil and Geodetic Engineering
Publisher:	[A. Šivic]
UDC:	628.349:66.087.5(043)
COBISS:	8546913
Views:	1093
Downloads:	391
Average score:	0 (0 votes)
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Other data

Secondary language:	English
Secondary title:	Phosphorus removal in packaged small wastewater treatment plants with application of electrocoagulation stirrer
Secondary abstract:	Existing small wastewater treatment plants in Slovenia are designed for secondary stage, i.e. organic matter removal, including those on sensitive areas. To prevent further eutrophication of water bodies in these areas some small wastewater treatment plants need an upgrade to tertiary treatment especially for total phosphorous removal. Physico-chemical processes can serve well for this purpose. In particular electrocoagulation (EC) has been proven as an efficient process. Although many times proven in laboratory tests EC is not commonly used in wastewater treatment plants for phosphorous removal due to some difficulties with the elements that need to be integrated in the plant and thus additional maintenance required. The thesis addresses this issue by using the EC process for phosphorous removal through the development of electrocoagulation stirrer (EC-stirrer), which besides mixing enables for phosphorous removal from domestic wastewater with minimum of 90% efficiency. The EC-stirrer is robust and fairly simple to be integrated in a small sequencing batch reactor (SBR) to improve their performance efficiency. The development of the EC-stirrer was based on laboratory tests, which proved 90% removal efficiency for orthophosphate from model and real domestic wastewater. Based on the laboratory experiments a prototype of EC-stirrer was developed and integrated in a pilot SBR. Prior to the integration, the SBR was optimized, i.e. the SBR cycles, where optimal length is a length that allows minimum of 90% ammonium removal, for second stage treatment with the emphasis on ammonium removal, as a key parameter for determining the optimal length of the cycle and its process phases. Cycle was optimized for (1) landfill leachate with high ammonium concentrations (380 % 890 mg/L), and (2) domestic wastewater with lower ammonium concentrations (27 % 116 mg/L). In the first case the optimal cycle was 12 hours long and for the second 8 hours. The latter was upgraded with the developed prototype EC-stirrer and its operation compared against SBR without EC-stirrer. Results demonstrate that SBR with EC-stirrer outperforms a common SBR not only in phosphorous removal, where SBR with EC-stirrer achieved 97% efficiency, but also in removal of suspended solids and organic matter. Within the thesis it was demonstrated that EC-stirrer can be integrated in existing small SBRs and significantly improve their performance. The EC-stirrer was patented in The Slovenian Intellectual Property Office, patent number: SI 25287 A.
Secondary keywords:	Environmental Protection;doctoral thesis;electrocoagulation;small wastewater treatment plant;phosphorus;sequencing batch reactor;
Type (COBISS):	Doctoral dissertation
Thesis comment:	Univ. v Ljubljani, Fak. za gradbeništvo in geodezijo
Pages:	XX, 134 str., 2 pril.
ID:	11061050