Full-scale investigation of ferrous dosing in sewers and a wastewater treatment plant for multiple benefits

Novel Use of a Ferric Salt to Enhance Mainstream Nitrogen Removal from Anaerobically Pretreated Wastewater

“…On the one hand, anoxic biofilms that were added to the A zone have been achievable at full scale, reported recently. − On the other hand, the added unit for iron dosing only has a volume of 7.5% of the anaerobic zone in the conventional A/A/O process, meaning that it can be directly re-fitted. Moreover, despite dosing into the return sludge, the average iron dosage in terms of treated wastewater was calculated to be 20 mg Fe/L, which is close to the typical range of iron salt dosed (10–40 mg Fe/L-treated wastewater) in many WWTPs. ,, Doing of FeCl 3 slightly reduced the pH of wastewater (Figure S2), which indicates that the alkalinity within wastewater is sufficient to buffer the proton produced in the Fe 3+ hydrolytic process. This study chose FeCl 3 because it is one of the most widely used flocculants in water management systems.…”

“…Moreover, despite dosing into the return sludge, the average iron dosage in terms of treated wastewater was calculated to be 20 mg Fe/L, which is close to the typical range of iron salt dosed (10−40 mg Fe/L-treated wastewater) in many WWTPs. 9,55,56 Doing of FeCl 3 slightly reduced the pH of wastewater (Figure S2), which indicates that the alkalinity within wastewater is sufficient to buffer the proton produced in the Fe 3+ hydrolytic process. This study chose FeCl 3 because it is one of the most widely used flocculants in water management systems.…”

Circular economy in hot-dip galvanizing with zinc and iron recovery from spent pickling acids

“…1c presents the owsheet of a WWTP, showing in green color the sludge line. The use of FeCl 2 instead of FeCl 3 has been reported in literature, generally showing that FeCl 2 , alone or in combination with FeCl 3 , is effective for reducing the presence of volatile sulfur compounds in the biogas produced in anaerobic sludge digesters, [29][30][31] even in studies focused on the improvement of methane (CH 4 ) production. 32 The FeCl 2 solution was used as partial substitute of the commercial FeCl 3 considering the normal dosing of iron at the WWTP.…”

Case study: Urban wastewater treatment plant with saline intrusions

“…With respect to the environment modification, the existing alternatives are also applicable to other units in the plant. This case requires the addition of an external compound into the collector system or WWTP unit, like nitrate, ferrous salts, injection/addition of air, pure oxygen, or alkali, to increase pH or metals to precipitate sulphide (Kulandaivelu et al, 2020). As an example, Churchill and Elmer (1999) tested the addition of nitrate which competes for the organic matter with sulphate reducing bacteria (SRB) avoiding H 2 S formation.…”

“…Its dosage in the collection network provided iron sufficient for desulfurization of H 2 S via iron sulphide precipitation from biogas in the anaerobic sludge digester (Ge et al, 2013;Salehin et al, 2019). Kulandaivelu et al (2020) evaluated its dosage in the sewer pipes and in the inlet of the of the Luggage Point WWTP (Queensland, Australia) and observed the decrease of H 2 S concentration in the gas phase in the anaerobic digester (36-45%) and an improvement in the digested sludge dewaterability of almost 10%.…”