Publicação
Defining package plant moving bed biofilm reactor for nitrogen and phosphorus removal
| Resumo: | This project investigated existing package plants for decentralized domestic wastewater treatment, focusing on the state-of-the-art technologies and proposing a new design using moving bed biofilm reactors (MBBR) for total nitrogen removal and absorbents for phosphorus removal. A detailed design and mass balance were performed for both an existing package plant and a newly designed MBBR- based plant. Additionally, lab-scale experiments were conducted to evaluate phosphorus removal using an aluminum-based granular adsorbent and to establish the correlation between carbon-to-nitrogen (C/N) ratios and denitrification efficiency in MBBR systems. Phosphorus removal experiments showed an adsorption capacity of 4.3 mg P/g of adsorbent, following a Langmuir isotherm model, with a regen- eration efficiency of 57.3% using 4% NaOH. Denitrification tests using MBBR technology at a C/N ratio of 14 demonstrated a maximum removal rate of 12.67 mg NO₃/h under low dissolved oxygen levels. Results indicated that nitrate removal increased with lower C/N ratios and higher recirculation ratios, while the denitrification rate per gram of volatile suspended solids (VSS) decreased as the C/N ratio increased. The existing package plant, designed for the removal of TSS, COD, and ammonia, had a working volume of 3.82 m³ and a hydraulic retention time (HRT) of 72 hours. Hydrolysis in the pri- mary sedimentation tank (PST) increased soluble COD, ammonia, and phosphorus levels before biolog- ical treatment, which achieved 96% BOD, 90% COD, and 97% ammonia removal. Denitrification oc- curred in the final sedimentation tank (FST) with 25% efficiency, alongside a 43% removal of TSS. The new MBBR design incorporated pre-denitrification, with a denitrification tank positioned after the PST and before BOD/COD removal. This setup had an HRT of 4 hours and a recirculation ratio of 600%, achieving a C/N ratio of 13. |
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| Autores principais: | Parsotamo, Anita |
| Assunto: | Package plants Decentralized wastewater treatment MBBR Phosphorus removal Denitrification Carbon to nitrogen ratio |
| Ano: | 2024 |
| País: | Portugal |
| Tipo de documento: | dissertação de mestrado |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Universidade Nova de Lisboa |
| Idioma: | inglês |
| Origem: | Repositório Institucional da UNL |
| Resumo: | This project investigated existing package plants for decentralized domestic wastewater treatment, focusing on the state-of-the-art technologies and proposing a new design using moving bed biofilm reactors (MBBR) for total nitrogen removal and absorbents for phosphorus removal. A detailed design and mass balance were performed for both an existing package plant and a newly designed MBBR- based plant. Additionally, lab-scale experiments were conducted to evaluate phosphorus removal using an aluminum-based granular adsorbent and to establish the correlation between carbon-to-nitrogen (C/N) ratios and denitrification efficiency in MBBR systems. Phosphorus removal experiments showed an adsorption capacity of 4.3 mg P/g of adsorbent, following a Langmuir isotherm model, with a regen- eration efficiency of 57.3% using 4% NaOH. Denitrification tests using MBBR technology at a C/N ratio of 14 demonstrated a maximum removal rate of 12.67 mg NO₃/h under low dissolved oxygen levels. Results indicated that nitrate removal increased with lower C/N ratios and higher recirculation ratios, while the denitrification rate per gram of volatile suspended solids (VSS) decreased as the C/N ratio increased. The existing package plant, designed for the removal of TSS, COD, and ammonia, had a working volume of 3.82 m³ and a hydraulic retention time (HRT) of 72 hours. Hydrolysis in the pri- mary sedimentation tank (PST) increased soluble COD, ammonia, and phosphorus levels before biolog- ical treatment, which achieved 96% BOD, 90% COD, and 97% ammonia removal. Denitrification oc- curred in the final sedimentation tank (FST) with 25% efficiency, alongside a 43% removal of TSS. The new MBBR design incorporated pre-denitrification, with a denitrification tank positioned after the PST and before BOD/COD removal. This setup had an HRT of 4 hours and a recirculation ratio of 600%, achieving a C/N ratio of 13. |
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