The Use of Oyster Shell Powders for Water Quality Improvement of Lakes by Algal Blooms Removal

Abstract

In this year, Koreans have a shortage in agricultural and drinking water due to severe algal blooms generated in major lakes. Waste oyster shells were obtained from temporary storage near the workplace at which oysters were separated from their shells. Heating (1000 o C for 1 h in air) was employed to convert raw oyster shell powders into calcium oxide powders that reacted efficiently with phosphorus and nitrogen to remove algal blooms from eutrophicated wastewater. As the dispersed amount of heated oyster shell powders was increased, water clarity and visual light penetration were improved. Coagulation, precipitation and car-bonation process of the heated oyster shell powders in a water purifier facilitated removal of eutrophication nutrient such as phosphorus and nitrogen, which is both beneficial and economically viable. CO 2 implantation by carbonation treatment not only produced thermodynamically stable CaO in oyster shells to derive precipitated calcium carbonate (PCC) but also accelerated algal removal by activation of coagulation and precipitation process. The use of oyster shell powders led to a mean reduction of 97% in total phosphate (T-P), a mean reduction of 91% in total nitrogen (T-N) and a maximum reduction of 51% in chemical oxygen demand (COD), compared with the total pollutant load of raw algal solution. Remarkable water quality improvement of algal removal by heated oyster shell powders and PCC carbonation treatment will allow utilization as water resources to agricultural or industrial use.

Effect of oyster shell powder on nitrogen releases from contaminated marine sediment

“…The main chemical composition of ROSP is 92.08% of calcium carbonate (CaCO 3 ) [17]. ROSP was calcined at ambient air condition inside an electric furnace at a constant temperature of 900°C for 1 h. After that heat treatment, it is mixed with some calcium carbonate containing CO 2 portion and most of crystalline CaO [18]. The crystalline CaO turned to be a hydrated form of calcite, namely [Ca(OH) 2 ].…”

Eutrophication: a threat to freshwater reservoirs and human health

“…The lanthanum modified bentonite (Phoslock™) and the and Modified Zeolite (Z2G1) represents the most innovative remediation materials (Copetti et al 2016;Zamparas and Zacharias 2014). A study realized by Huh et al (2016) showed that heated oyster shell powders is also a potential material to reduce the presence of phosphate and nitrogen in eutrophicated waters.…”

A perspective of chemical treatment for cyanobacteria control toward sustainable freshwater development

“…Visible transparency of algal freshwater was also gradually converted from dark green to colorless according to the alteration of added amounts of calcined powders as shown in Fig. 5 [89]. For the total pollutant load of the algal solution, the mean removal (or reduction) efficiency of total phosphorus (T-P), total nitrogen (T-N), and chemical oxygen demand (COD) was recorded at 96.5%, 91.4%, and 33.8%, respectively [89].…”

“…5 [89]. For the total pollutant load of the algal solution, the mean removal (or reduction) efficiency of total phosphorus (T-P), total nitrogen (T-N), and chemical oxygen demand (COD) was recorded at 96.5%, 91.4%, and 33.8%, respectively [89]. The calcium hydroxide and carbonation combination in algae-containing water significantly contributed to improve water quality which is very dependent on the addition amount of calcined oyster shell powder [90].…”

“…5. The visual performance after algae coagulation process in eutrophic waters using oyster shell powder: the powder was fed from 1 g to 5 g into raw algae water of 0 g. [89] lose their H + . However, dolomite coagulator dissolves the oppositely-charged divalent cations such as Ca 2+ and Mg 2+ and cation bridges with adjacent algae coagulation.…”