Cationic starch for microalgae and total phosphorus removal from wastewater

Abstract

The city of Logan, Utah treats wastewater in 460 acres of facultative lagoons. Naturally growing algae in these lagoons uptake nutrients and remediate the wastewater, but require coagulation and flocculation for separation from wastewater. Cationic corn starch and cationic potato starch with a degree of substitution 1.34 and 0.82, respectively, were synthesized using 3-methacryloyl amino propyl trimethyl ammonium chloride and tested on Scenedesmus obliquus and lagoon wastewater. The zeta potential of the cationic starches tested over a pH range 5.0-10.0 showed an average of 116.0 and 115.1 mV for cationic corn starch and cationic potato starch, respectively. Total suspended solids removals of 90 and 85% were achieved with cationic corn starch and cationic potato starch, respectively, when tested with S. obliquus. Tests with wastewater showed total suspended solids removals of 80 and 60% for cationic corn starch and cationic potato starch, respectively. Total phosphorus removal values from wastewater were approximately 33, 29, and 42% for cationic corn starch, cationic potato starch, and alum, respectively, for a coagulant/algae ratio of 1.4 (wt/wt). These results indicate that cationic starch has the potential to replace alum for algae harvesting and wastewater treatment making it a suitable alternative to inorganic coagulants and flocculants.

Ecotoxicological assessment of flocculant modified soil for lake restoration using an integrated biotic toxicity index

“…Anthony and Sims (2013) find that cationic starch can effectively flocculate algae cells and remove total phosphorus in wastewater with an upward trend of TP removal with increasing dosage. Cationic starches serve as substrates in anaerobic digestion or fermentation processes using the harvested biomass as feedstock and such biomass can be safely used as animal feed or fertilizer (Anthony and Sims, 2013). Cationic starch modified soil has been reported by Shi et al (2016) as the effective algae flocculant with the loading of 0.11 g/L for a removal efficiency of 86%.…”

“…To improve the HABs removal using clays, chitosan is used to modify the local soils and applied to small natural waters to control both cyanobacteria blooms and sediment nutrient release, leading to recovery in submerged macrophytes Pan, 2015, 2013;Pan et al, 2012). Anthony and Sims (2013) find that cationic starch can effectively flocculate algae cells and remove total phosphorus in wastewater with an upward trend of TP removal with increasing dosage. Cationic starches serve as substrates in anaerobic digestion or fermentation processes using the harvested biomass as feedstock and such biomass can be safely used as animal feed or fertilizer (Anthony and Sims, 2013).…”

“…Recent studies indicate that toxic Al 3þ could be released after alum application at low pH (<6.0), and sediment-capping with alum could inhibit microbial nitrification and denitrification under aerobic conditions (Gibbs and Oezkundakci, 2011). Recently, natural flocculant materials, such as chitosan and cationic starch, were developed as environmental friendly materials to control harmful algal blooms because of their high flocculation efficiency (Anthony and Sims, 2013;Hansel et al, 2014;Letelier-Gordo et al, 2014;Xu et al, 2013). To improve the HABs removal using clays, chitosan is used to modify the local soils and applied to small natural waters to control both cyanobacteria blooms and sediment nutrient release, leading to recovery in submerged macrophytes Pan, 2015, 2013;Pan et al, 2012).…”

Algae-based biofilm productivity utilizing dairy wastewater: effects of temperature and organic carbon concentration

“…Turbidity of the water was measured at 890 NTU (Hach 2100Q turbidimeter). Algae biomass inoculum for the laboratory RABRs was collected from the pilot scale RABR systems currently operating at the Logan City wastewater treatment facility, a 460 acre (1.86 km 2 ) open lagoons system [19]. Visual microscopy of the pilot scale RABR based biofilm indicated that the collected algae biomass contained a variety of algae species, with Pseudanabaena , Oscillatoria , and Chroococcus as the predominant species.…”

Chitosan-graft-polydiallyldimethyl ammonium chloride for microalgae harvesting from wastewater

“…To achieve sustainability in microalgae harvesting, organic coagulants must be tested and utilized. Organic coagulants such as cationic starch, chitosan, and guar gum have been to a certain extent researched for microalgae harvesting [9,[11][12][13]. Organic coagulants are naturally available, inexpensive, and can provide a source of carbon for downstream processes such as in fermentation or anaerobic digestion of the harvested biomass.…”