Effects of Phosphates on Coagulation and Sedimentation of Turbid Waters

Abstract

The increased consumption of synthetic detergents in recent years has prompted research into the effects of these substances on conventional water treatment processes. Operational difficulties have been attributed to the presence of synthetic detergent compounds in treatment plant influents, and considerable research has been undertaken to establish what effects synthetic detergent components have on treatment processes, principally coagulation, sedimentation, and filtration. The major components of present‐day commercial synthetic detergents are surface‐active agents and builder compounds. The most important compounds among the builders are the condensed phosphates, sodium tripolyphosphate (STP), and tetrasodium pyrophosphate (TSPP). The purpose of this investigation was to evaluate the effects of STP and TSPP on the clarification of hard, turbid water under conditions of continuous flow in a pilot‐scale treatment plant. Results show that STP and TSPP, in relatively high concentrations, are capable of interfering with the coagulation and sedimentation of hard, turbid waters. The effects of TSPP and STP appear to be equal. The magnitude of the interference is reduced by reasonable increases in the coagulant dosage, improvement of mixing and flocculation characteristics, and by an increase in settling time.

Factors governing microalgae harvesting efficiency by flocculation using cationic polymers

“…Phosphorus is present in the algal medium as orthophosphates and decreases in concentration gradually with culture age. Residual phosphorous has been reported to impact coagulation and flocculation in wastewater treatment (Liu & Liss, 2007;Morgan, 1958;Park et al, 2016). The presence of phosphorous as phosphates in wastewater hindered the flocculation and sedimentation processes (Morgan, 1958).…”

“…Residual phosphorous has been reported to impact coagulation and flocculation in wastewater treatment (Liu & Liss, 2007;Morgan, 1958;Park et al, 2016). The presence of phosphorous as phosphates in wastewater hindered the flocculation and sedimentation processes (Morgan, 1958). A higher flocculant dose and a longer settling time were required to overcome the interference caused by phosphate compounds (Morgan, 1958;Park et al, 2016).…”

“…The presence of phosphorous as phosphates in wastewater hindered the flocculation and sedimentation processes (Morgan, 1958). A higher flocculant dose and a longer settling time were required to overcome the interference caused by phosphate compounds (Morgan, 1958;Park et al, 2016). Conversely, the gravitational settling velocity of sludge flocs was enhanced for wastewater with reduced phosphorous concentration (Liu & Liss, 2007).…”

Celebrating Jim Morgan: A Brilliant Teacher and Caring Mentor

“…They sampled rivers together and brought the water back to the laboratory for analyses. Tracking the biggest pollution topic of the day, Morgan and Engelbrecht published three important papers on polyphosphates and alkyl benzenesulfonate (ABS) compounds from synthetic detergents. − Phosphates were responsible for eutrophication of lakes and ABS caused serious “sudsing” problemswalls of suds 10–20 ft highat wastewater treatment plants, in rivers, and beyond.…”