A preliminary study of processing seafood shells for eutrophication control

Abstract

Shells from the seafood processing industry in New Zealand are currently an under-utilized waste resource. In this study we investigate the processing conditions required for the creation of calcium oxide (lime) from green-lipped mussel (Perna canaliculus) and pacific oyster (Crassostrea gigas) shells. Lime is commonly used in wastewater treatment for the removal of phosphorous compounds from water, thus providing a means of eutrophication control. Mussel and oyster shells were processed in a horizontal tube furnace at various temperatures (650-800 • C) in both air and nitrogen environments. From X-ray diffraction (XRD) and weight-loss measurements, the extent of limestone calcination was found to increase with increasing furnace temperature for both shell species and furnace atmospheres. Analysis showed that the lime was present as a layer on the surface of the shell particles. From scanning electron microscope (SEM) images, significant changes in the surface morphology of the raw shells were observed as a result of heat treatment in both air and nitrogen atmospheres. Preliminary testing of shells heat-treated in both air and nitrogen atmospheres indicated that both types of shell removed about 90% of phosphates in water within 30 min, whereas up to 40% of phosphates were removed with untreated shells. Our results for heat-treated oyster shell differ slightly with studies in the literature, which report an absence of compositional and structural changes in an air atmosphere. 

Improvement of poly-γ-glutamic acid biosynthesis in a moving bed biofilm reactor by Bacillus subtilis NX-2

“…The moving bed biofilm reactor (MBBR) system, widely used in wastewater treatment process, was developed here based on the conventional activated sludge disposal and the fluidized-bed reactor (Currie et al, 2007). Its carriers can provide a suitable microenvironment for cell growth, leading to formation of a biofilm and a reduction in the washout from the system .…”

Kinetics of Hg(II) adsorption and desorption in calcined mussel shells

“…In a study carried out in New Zealand, Currie et al [3] showed that the use of calcined mussel shells eliminated around 90% of the phosphates in the water samples analysed, whereas the efficacy decreased to 40% when untreated mussel shells were used. However, information about the capacity of this material to retain heavy metals, specifically Hg(II), is scarce.…”

Carrier effects on oxygen mass transfer behavior in a moving‐bed biofilm reactor

“…It is a highly effective biological treatment process that was developed on the basis of the conventional activated sludge process and the fluidizedbed reactor. [2,12] Researchers have shown that MBBR has many excellent traits such as high biomass, high Chemical Oxygen Demand (COD) loading, strong tolerance to loading impact, relatively smaller reactor size, *Correspondence to: Wen Ying Li, Key Laboratory of Coal Science and Technology, Taiyuan University of Technology, Taiyuan 030024, China. E-mail: ying@tyut.edu.cn no sludge bulking problem, etc.…”