Electrochemical Sulfide Control in Municipal Sewer Systems: A Pilot-Scale Investigation
Author
Ucaj, Elisa
Term
4. term
Publication year
2026
Submitted on
2026-06-04
Pages
56
Abstract
Hydrogen sulfide (H2S) is a pervasive odor, corrosion, and safety issue in wastewater systems, where anaerobic conditions drive sulfate reduction. Conventional mitigation relies on either end-of-pipe air treatment or in-sewer chemical dosing, with iron salts commonly used to precipitate sulfide. This thesis investigates pilot-scale electrochemical (EC) iron dosing as an integrated alternative that generates iron in situ, raises alkalinity, and precipitates sulfide within the sewer flow. The goal is to test EC under realistic conditions in Frejlev, Aalborg municipality, and to evaluate relationships among current density, conductivity, iron generation, and H2S suppression. A semi-continuous end-of-the-line EC unit using a five-plate bipolar iron cell powered by a DC supply was operated across multiple runs, monitoring current, conductivity, temperature, and H2S. Datasets were time-aligned and partitioned into batches, and an analytical framework was applied to compute current density, theoretical iron dissolution, and cumulative iron concentrations. The results section reports electrical behavior (current–time, current density–conductivity), H2S concentration profiles under active EC, comparisons of iron concentration and outlet H2S, and operational limitations and considerations. Overall, the pilot tests characterize how conductivity and applied voltage shape current density and theoretical iron dosing, and assess the associated H2S dynamics—informing operating windows and considerations for scalable deployment in municipal sewers.
Hydrogensulfid (H2S) udgør et udbredt arbejdsmiljø-, korrosions- og lugtproblem i spildevandssystemer, hvor anaerobe forhold fremmer sulfatreduktion. Konventionelle strategier omfatter enten end-of-pipe-luftrensning eller in-situ kemisk dosering, hvor jernsalte ofte anvendes til at udfælde sulfider. Denne afhandling undersøger en pilotmålelig elektro-kemisk (EC) jern-dosering som et integreret alternativ, der genererer jern in situ, øger alkalinitet og udfælder sulfider i selve kloakstrømmen. Formålet er at afprøve EC under realistiske forhold i Frejlev, Aalborg Kommune, og evaluere sammenhænge mellem strømtæthed, ledningsevne, jernfrigivelse og undertrykkelse af H2S. Et semi-kontinuert end-of-the-line EC-anlæg med en fem-pladers bi-polær jerncelle drevet af en jævnstrømskilde blev testet i flere forsøg, hvor strøm, ledningsevne, temperatur og H2S blev overvåget. Data blev tidsjusteret og inddelt i batches, og et analytisk rammeværk baseret på beregning af strømtæthed, teoretisk jerndissolution og kumulative jernkoncentrationer blev anvendt. Resultatafsnittet dokumenterer elektrisk adfærd (strøm–tid, strømtæthed–ledningsevne), H2S-koncentrationsprofiler under aktiv EC og sammenstillinger af jernkoncentration og H2S ved udløb, samt driftsbegrænsninger og -overvejelser. Samlet set karakteriserer pilotforsøgene, hvordan ledningsevne og påtrykt spænding former strømtæthed og teoretisk jern-dosering, og de vurderer de tilhørende H2S-dynamikker—med henblik på at informere driftsvinduer og skalerbar implementering i kommunale kloakker.
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