The properties of sludge formed as a result of coagulation of backwash water from filters removing iron and manganese from groundwater

Abstract

The standard groundwater treatment technology is a simple, non-chemical reagent technology based on aeration and filtration processes. This treatment technology is resulted in the formation of groundwater treatment sludge (GWTS). Because one of the elements of sustainable development is the possibility of their reuse, that water treatment plant operators are looking for new ways of managing these sludges. At present, not all factors determining the adsorptive capacity of water treatment sludge are known. The explanation why the adsorption capacity of sludge with a similar structure and chemical composition may differ significantly will allow for their wider use as adsorbents. The information which must be known to ensure proper sludge management are the quality, chemical composition and texture characteristics of the GWTS. The sludges were characterized by X-ray diffraction, X-ray fluorescence, Fourier transform infrared spectroscopy and N 2 adsorption/desorption isotherms. The results showed that the composition and properties of the GWTS depend primarily on the quality parameters of the raw water and the processes and reagents used in its treatment technology. GWTS contains mainly amorphous iron oxides. Sludges are characterized by a large specific surface area (145 m 2 /g). Due to composition and textural parameters, GWTS demonstrates good adsorption properties toward different compounds such as heavy metals and metalloids. In this article, the authors describe the relationship between properties of resulting sludge and the properties of groundwater, the treatment technology and backwash water treatment from rapid filters.

Removal of Heavy Metals and Metalloids from Water Using Drinking Water Treatment Residuals as Adsorbents: A Review

“…The low-intensity XRD peaks are indicative of quartz and calcite. All GWTRs presented in this research [40,53,61] show a similar phase composition, indicating that sludge are rather amorphous material; the only crystalline mineral that was found was quartz [40].…”

“…Further oxidation of Fe and Mn takes place in the filter bed, enhancing filter effectiveness. As long as there are no other pollutants in the water, no additional chemicals need to be used in this process [53,[74][75][76]. The filters are periodically backwashed, and the contaminants retained in the filter bed during the water purification process are washed away and collected in a clarifier.…”

“…WTRs, sometimes referred to as water treatment sludge or waterworks sludge, are by-products generated by drinking water treatment plants. Each year, several million tons of WTRs are produced [50][51][52][53][54]. Their disposal is problematic and expensive due to environmental restrictions and has provided the impetus for research into their reuse [55].…”

Combined Action of Adsorption and Catalytic Oxidation in Aluminum Dye Removal by Groundwater Treatment Waste

“…Nowadays, the reuse of drinking water treatment sludge has become an increasingly important issue (Babatunde & Zhao, 2007). Therefore, GWTW is extensively studied as a suitable adsorbent for nickel, cadmium, and CO 2 (Wołowiec et al, 2019;Ong et al, 2017;Siswoyo et al, 2014;Novoselova, 2013) and as a coagulant to remove natural organics from river water (Albrektienė et al, 2019).…”

Iron-Based Water Treatment Residuals: Phase, Physicochemical Characterization, and Textural Properties

“…Second, residuals arising from the treatment of groundwater with a high concentration of Fe(II) and Mn(II) or infiltration water treatment called groundwater treatment residuals (GWTRs). Usually, groundwater treatment is a simple, nonchemical reagent technology based on aeration and filtration processes [ 11 ]. The iron salts present in groundwater easily hydrolyze to soluble Fe(II) hydroxide and then oxidize and precipitate as soluble Fe(III) hydroxide, which is the primary component of the sludge.…”