Research on and application of low-temperature calcination on waste Taiwanese hard clam shell during Taiwanese hard clam aquaculture

Abstract

This study uses a circular economy-regenerative value addition approach. Pre-treated waste clam shells were calcined at a low temperature (about 300 °C) and then crushed into clamshell powder. Taiwanese hard clam shell (THCS) powder and commercially available calcium carbonate products, such as low-temperature calcined oyster shell (OS) powder, slaked lime, and calcium carbonate, were compared experimentally, and the safety of THCS powder was determined. In the safety evaluation, the Vibrio-like bacteria test results showed that no colony growth was found for the low-temperature-calcined THCS powder, indicating that it did not contain Vibrio-like bacteria. Tolerance test results showed that high-dose slaked lime will cause high Taiwanese hard clam mortality, and the survival rates of other groups were all 100%. In addition, slaked lime had the most significant effect on increasing the water pH. OS powder had the greatest effect on increasing the calcium ion concentration in the water, followed by THCS power. The aquaculture benefit-related experimental results showed that the low-temperature calcined OS powder and THCS powder groups had the most favorable performance in terms of Taiwanese hard clam growth rate, shell weight, and shell thickness. This study used different calcium carbonate products as additives in Taiwanese hard clam aquaculture ponds and observed growth differences between the different groups. These results indicated that the low-temperature calcination of THCS in Taiwanese hard clam aquaculture can effectively replace the commonly used OS powder, slaked lime, and calcium carbonate products in traditional aquaculture. Furthermore, it can effectively solve the problem of THCS waste accumulation, promote environmental beautification, create a circular economy and aquaculture application value, and conform to the economic benefits of aquaculture.