Fiber sludge as a bioadsorbent for cation removal from industrial wastewaters
Koypish, Svetlana (2021)
Koypish, Svetlana
2021
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Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:amk-202101311733
https://urn.fi/URN:NBN:fi:amk-202101311733
Tiivistelmä
The topic of the thesis concerns reutilization of fibre sludge waste to remove metals from industrial wastewater. The main objective of the thesis was to discover if such application is possible. The fo-cus was kept on the properties of fibre sludge and on the issues affecting adsorption. The thesis is theory-based. And the primary research method used primarily was literature review. The articles used in the thesis are based on the laboratory studies. The adsorption experiments were conducted using the stock solutions. Three kinds of fibre sludge – based adsorbents were studied. They were the original non-modified fibre sludge, fibre sludge subjected to slow pyrolysis, and chemically activat-ed fibre sludge. The impact of the pretreatment methods and adsorption parameters was evaluated. The fibre sludge samples used in each of the three cases resulted from different feedstocks and pulp-ing processes. Therefore, the obtained conclusions are specific for each of the three cases concerned in the thesis.
It was found that the fibre sludge can adsorb metals from aqueous solutions without being chemical-ly activated. The metals adsorbed are Pb, Ni, Cd, Co. The adsorption yield was over 70% for all the metals within the pH range from 2 to 5. The best pH for the adsorption was 4.5. The best biomass concentration was 1%. Concerning the contact time, 70%-89% of all the four metals were adsorbed within 15 min. The surface area was mentioned as a significant parameter. The chemically activated fibre sludge adsorbed the following metals Cu, Co, Ni , Cr, Zn. The pH of adsorption was 6.2. The adsorption yield of 93% was achieved within 10 s for all the five metals. The pyrolyzed fibre sludge was analyzed but not experimentally tested as adsorbent. Based on the analyses the following con-clusions were reported. The material from the same factory is homogeneous unlike the samples from different factories. High inorganic content in fibre sludge was reported to reduce mechanical strength of granular adsorbent produced from fibre sludge. The laboratory studies described in the thesis re-port fibre sludge to be a suitable and even commercially competitive material for metal adsorption from water. Therefore, industrial scale experiments using real wastewater are to be conducted to prove the reliability of fibre sludge to be an adsorbent or its precursor.
It was found that the fibre sludge can adsorb metals from aqueous solutions without being chemical-ly activated. The metals adsorbed are Pb, Ni, Cd, Co. The adsorption yield was over 70% for all the metals within the pH range from 2 to 5. The best pH for the adsorption was 4.5. The best biomass concentration was 1%. Concerning the contact time, 70%-89% of all the four metals were adsorbed within 15 min. The surface area was mentioned as a significant parameter. The chemically activated fibre sludge adsorbed the following metals Cu, Co, Ni , Cr, Zn. The pH of adsorption was 6.2. The adsorption yield of 93% was achieved within 10 s for all the five metals. The pyrolyzed fibre sludge was analyzed but not experimentally tested as adsorbent. Based on the analyses the following con-clusions were reported. The material from the same factory is homogeneous unlike the samples from different factories. High inorganic content in fibre sludge was reported to reduce mechanical strength of granular adsorbent produced from fibre sludge. The laboratory studies described in the thesis re-port fibre sludge to be a suitable and even commercially competitive material for metal adsorption from water. Therefore, industrial scale experiments using real wastewater are to be conducted to prove the reliability of fibre sludge to be an adsorbent or its precursor.