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1

Phosphorus removal by microelectrolysis and sedimentation in the integrated devices

Libecki Bartosz, Mikołajczyk Tomasz

Archives of Environmental Protection

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2021

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Vol. 47, no. 1

3--9

EN

This paper presents the results of tests performed on an installation with an aerated microelectrolytic bed (MEL-bed) and sludge sedimentation. The systems were designed in two versions, differing in the aeration method, i.e., a mechanically aerated coagulator (MAC) and an automatically aerated coagulator (AAC). The experiment demonstrated a high (approx. 84%) efficiency of phosphorus removal from a model solution for both versions. The corroding bed was the source of iron in the solution. In the initial phase aeration method affected the phosphorus removal rate, flocculation and sedimentation processes. Physical and chemical changes in the MEL-bed packing were observed.

PL

W pracy zaprezentowano wyniki testów urządzenia z napowietrzanym złożem mikroelektrolitycznym (MEL-bed) i sedymentacją osadu. Urządzenie zaprojektowano w dwóch wersjach, różniących się sposobem napowietrzania. tj.: mechanical aerated coagulator (MAC) oraz automatically aerated coagulator (AAC). Eksperyment wykazał wysoką ok. 84% skuteczność usuwania fosforu z roztworu modelowego dla obydwu wersji. Korodujące złoże było źródłem żelaza w roztworze. Sposób napowietrzania miał wpływ na szybkość usuwania fosforu w początkowej fazie trwającej do 1 h oraz na procesy flokulacji i sedymentacji. Zaobserwowano zmiany fizyczne i chemiczne wypełnienia złoża MEL-bed.

2

Removal of nitrates and organic compounds from aqueous solutions by zero valent (ZVI) iron reduction coupled with coagulation/precipitation process

Wiśniowska Ewa, Włodarczyk-Makuła Maria

Archives of Environmental Protection

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2020

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Vol. 46, no. 3

22-29

EN

The removal of nitrates from aqueous solutions is cumbersome because of their high solubility in water. The use of zero-valent iron (ZVI) for the reduction of nitrates is the chemical process and it is an alternative method to the biological ones. The aim of the present study was to evaluate the effectiveness of nitrates removal from water solution by using the ZVI process. The process was coupled with the removal of COD, phosphates and turbidity by using by-products of nitrates reduction. Batch tests were performed to evaluate the effectiveness of ZVI in the removal of nitrates from aqueous solutions. The effectiveness of nitrates removal was analyzed after 5, 10, 20, 30 and 60 min. and compared to the initial concentration of pollutants. Simultaneously analysis of ammonium nitrogen and nitrites was controlled to identify products of nitrates reduction under various pH. The removal of COD, phosphates and turbidity was also performed in batch tests. The effectiveness of the removal by using three types of chemicals was compared – PIX, FeSO4, and waste Fe2+/Fe3+ from the ZVI process. The results obtained in the study indicate that ZVI can be effectively used in the treatment of water polluted with nitrates and the by-products of the process could be further applied in the removal of COD, phosphates and turbidity. Based on the results the method should be advised as a promising alternative to the technologies used nowadays under technical scale as a technology that fits with a circular economy.

3

Automotive fleet repair facility wastewater treatment using air/ZVI and air/ZVI/H2O2 processes

Bogacki J. P., Al-Hazmi H.

Archives of Environmental Protection

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2017

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Vol. 43, no. 3

24--31

EN

Advanced automotive fleet repair facility wastewater treatment was investigated with Zero-Valent Iron/Hydrogen Peroxide (Air/ZVI/H2O2) process for different process parameters: ZVI and H2O2 doses, time, pH. The highest Chemical Oxygen Demand (COD) removal efficiency, 76%, was achieved for ZVI/H2O2 doses 4000/1900 mg/L, 120 min process time, pH 3.0. COD decreased from 933 to 227 mg/L. In optimal process conditions odor and color were also completely removed. COD removal efficiency was increasing with ZVI dose. Change pH value below and over 3.0 causes a rapid decrease in the treatment effectiveness. The Air/ZVI/H2O2 process kinetics can be described as d[COD]/dt = -a [COD]tm, where ‘t’ corresponds with time and ‘a’ and ‘m’ are constants that depend on the initial reagent concentrations. H2O2 influence on process effect was assessed. COD removal could be up to 40% (560 mg/L) for Air/ZVI process. The FeCl3 coagulation effect was also evaluated. The best coagulation results were obtained for 700 mg/L Fe3+ dose, that was slightly higher than dissolved Fe used in ZVI/H2O2 process. COD was decreased to 509 mg/L.

PL

Ścieki z zakładu naprawczego floty samochodowej poddano oczyszczaniu z wykorzystaniem żelaza metalicznego i nadtlenku wodoru (Air/ZVI/H2O2). Badano wpływ dawki żelaza i nadtlenku wodoru, czasu i pH na efektywność procesu. Największy stopień usunięcia ChZT, 76%, uzyskano dla dawek ZVI/H2O2 4000/1900 mg/L, czasu 120 min i pH 3.0. ChZT zmniejszono z 933 do 227 mg/L. Dodatkowo uzyskano całkowite usunięcie barwy i zapachu. Skuteczność usunięcia ChZT rosła wraz ze wzrostem zastosowanej dawki ZVI. Zmiana pH na inne niż 3, powoduje gwałtowne zmniejszenie efektywności procesu. Kinetyka procesu może zostać opisana z wykorzystaniem równania d[COD]/dt = -a [COD]tm, gdzie ‘t’ oznacza czas a ‘a’ i ‘m’ są stałymi zależnymi od początkowego stężenia reagentów. Badano także wpływ H2O2 na efektywność procesu. Skuteczność usunięcia ChZT wynosi 40% (560 mg/L) w przypadku zastosowania ZVI bez dodatku H2O2. Określono także skuteczność koagulacji z wykorzystaniem FeCl3. Najlepsze rezultaty uzyskano dla dawki Fe3+ 700 mg/L, zmniejszając ChZT do 509 mg/L.

4

Desalination of groundwater and impoundments using Nano-Zero Valent Iron, n-Fe°

Antia D.D.J.

Meteorology Hydrology and Water Management. Research and Operational Applications

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2015

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Vol. 3, Iss. 1

21--38

EN

Salinization of groundwater is a major problem, particularly in areas with limited infrastructure. 14 diffusion reactors are operated diabatically at -8°C to 20°C to determine the amount of NaCl removed by n-Fe°. The reactors establish NaCl removal by Fe°: (i) 44,000-77,000 nm particle size (PS) = 0.0675-0.1925 g L-1 [feed water (FW) = 0.89 g L-1]; (ii) 50 nm PS = 0.953-1.14 g L-1 [FW = 1.095-1.19 g L-1]; (iii) 50 nm PS under nitrogen saturation (0.1-0.2 MPa) = 9.693 g L-1 [FW = 10 g L-1]; (iv) <0.01 g 50 nm PS L-1 under nitrogen saturation (0.1-0.2 MPa) = 1.564 g L-1 [FW = 4 g L-1]; (v) 50 nm PS modified by nitrogen saturation (PSN) = 5.52 g L-1 [FW = 6.89 g L-1]. Desalination commences at a time, t, after the n-Fe° is added to the water, and continues with an exponential decline until a base (equilibrium) salinity is reached. The effectiveness of n-Fe° as a desalination agent appears to increase with increased water salinity. Placement of PSN in an existing impoundment, or aquifer, may provide a cost effective, zero energy, partial desalination solution, which can be used to support emergency relief, agriculture and extractive industries.