Removal efficiency of Gram-positive and Gram-negative bacteria using a natural coagulant during coagulation, flocculation, and sedimentation processes

Abstract

Staphylococcus sp. as Gram-positive and Escherichia coli as Gram-negative are bacterial pathogens and can cause primary bloodstream infections and food poisoning. Coagulation, flocculation, and sedimentation processes could be a reliable treatment for bacterial removal because suspended, colloidal, and soluble particles can be removed. Chemical coagulants, such as alum, are commonly used. However, these chemical coagulants are not environmentally friendly. This present study evaluated the effectiveness of coagulation, flocculation, and sedimentation processes for removing Staphylococcus sp. and E. coli using diatomite with standard jar test equipment at different pH values. Staphylococcus sp. demonstrated 85.61% and 77.23% significant removal in diatomite and alum, respectively, at pH 5. At pH 7, the removal efficiency decreased to 79.41% and 64.13% for Staphylococcus sp. and E. coli, respectively. At pH 9, there was a decrease in Staphylococcus sp. after adding diatomite or alum compared with that of E. coli. The different removal efficiencies of the Gram-positive and Gram-negative bacteria could be owing to the membrane composition and different structures in the bacteria. This study indicates that diatomite has higher efficiency in removing bacteria at pH 5 and can be considered as a potential coagulant to replace alum for removing bacteria by the coagulation process.

Review of hospital effluents: special emphasis on characterization, impact, and treatment of pollutants and antibiotic resistance

“…Another study evaluated the effectiveness of coagulation processes in eliminating Staphylococcus and E. coli by using diatomite. The results proved a significant removal of 85.61% (Sha'arani et al, 2019).…”

Sustainable Water Use in a Fruit Processing Plant: Evaluation of Microbiological and Physicochemical Properties of Wash Water after Application of a Modular Water Recovery System

“…On the other hand, each module of the water treatment system carries out processes with properties that reduce the number of microorganisms. The use of coagulation, flocculation, and sedimentation is usually one of the first stages of water treatment, which contributes to mechanically 'trapping' some of the bacteria in the solid fraction [44]. As noted by Xiangli et al the implementation of coagulation prior to the use of full-scale ultrafiltration is an effective method in the production of drinking water [45].…”

An assessment of technological development and applications of decentralized water reuse: A critical review and conceptual framework

“…Therefore, there is a constant search for improved coagulants, especially on the use of coagulants derived from natural sources (i.e., chitosan, Moringa oleifera , diatomite) and laboratory scale studies were conducted to identify the optimal coagulant dose for various applications. Diatomite (1.0–2.5 mg/L) added to 50 NTU turbid water during sedimentation stage produced 0.87 log reduction of E. coli at pH 5 (Sha'arani et al, 2019). While the laboratory scale studies have shown promising results, the fact that need for conducting detailed study to identify an optimal coagulant dosage has limited the deployment of new types of coagulants for the market due to the need for involvement of an expert in the field rather than a technology managed by non‐experts.…”