Coagulation efficiency and flocs characteristics of recycling sludge during treatment of low temperature and micro-polluted water

Evaluation of drinking water treatment combined filter backwash water recycling technology based on comet and micronucleus assay

“…2-4 of water samples produced by the recycling process were not obviously increased, which forcefully indicated that the recycling process could be used as an alternative method to treat low turbidity water, saving water resources. In addition, Zhou et al (2012) stated that the removal of organic substances by hydrolyzed metal coagulants is likely to cause a neutralizing effect. The anionic sites over the surface of organic materials could be bound by metal species like Al 3+ and Fe 3+ present in the PFAC, and then particles formed by this means can be removed during the subsequent sedimentation or filtration units.…”

“…Gottfried et al (Gottfried et al, 2008) stated that the addition of reused backwash water solids was beneficial in increasing the collision and adhesion probabilities of suspended particles to further enhance the traditional treatment technology, and notably higher removal efficiency for DOC and UV 254 was found, when the raw water blended with 5% and 10% by volume of filter backwash water was re-input into the conventional drinking water treatment. Xu et al (2009) and Zhou et al (2012) thought that the remaining amorphous aluminum and ferric hydroxide in the waste sludge probably did not fully react during the traditional process, and thus could be used as aggregated cores in the recycling process, enhancing the collision probabilities among particles. According to other studies, the removal of Cryptosporidium oocysts could be enhanced by 4.3%-20% when untreated filter backwash water was recycled to the input of the coagulation process (Cornwell and Lee, 1994;Cornwell et al, 1987;Cristale et al, 2013).…”

A Pilot Study of the Sludge Recycling Enhanced Coagulation–Ultrafiltration Process for Drinking Water: The Effects of Sludge Recycling Ratio and Coagulation Stirring Strategy

“…Application of sludge recycling instead of directly discharging could take full advantage of the sludge for improving the performance of drinking water treatment [10]. Sludge recycling is a practice known in the wastewater treatment field, since sludge has been proven to be capable of purifying water [11]. The main advantages of the sludge recycling approach are as follows:…”

Characterization of drinking water treatment sludge after ultrasound treatment

“…Chemical safety and bio-stability are the two main concerns of reuse process [3], thus limiting the concentration of organic matter and metal ions, and controlling microbial activity to a low level within sludge before recycling can help ensure the safety of the recycle outputs. The reuse of DWTS can contribute toward an improvement of treatment performance regarding the particulates and phosphorus removal [3,4], and an improvement in settling and dewatering characteristics of the re-coagulation flocs as well. However, the enhanced removal of pollutions, i.e., organic matter of recycling processes sometimes is not desirable due to the release of pollutions (humic-like and protein-like substances) that are derived from sludge [2,5,6].…”