Crustacean waste

Chitin is a homopolymer of AT-acetyl-D-glucosamine residues and is a major structural component in the exoskeletons of crustaceans, mollusks, arthropods, and the cell walls of numerous fungi and algae. Owing to its widespread presence in both terrestrial and aquatic organisms, chitin is second only to cellulose as the most abundant biopolymer on the Earth (Shahidi and Abuzaytoun, 2005). On a dry weight basis, shrimp, crab, lobster, prawn, and crayfish have been reported to contain between 14% and 35% chitin, while deproteinized dry shell waste of Antarctic krill contains approximately 40% crude chitin (Haard et al, 1994). Crustaceans are the primary sources of chitin used in industry. Chitin can be extracted from shellfish and crustacean waste by mixing with a dilute add to induce demineralization, followed by a deproteini-zation step in a hot alkaline solution (Synowiecki and Al-Khateeb, 2003). 

One of the most studied biosorbent is chitin, which is an abundant biopolymer found in crustaceans, insects and fungus. This biopolymer is commercially purified by alkaline deproteinization, acid demineralization and decoloration by organic solvents of crustaceans wastes (Pastor, 2004). An additional stronger alkaline treatment of chitin produces deacetylated chitin. If the acetylation degree (DA) decreases at 39% or less, the biopolymer is named chitosan. Hence, the DA of chitin is variable and depends on the process conditions (alkali concentration, contact time, temperature, etc.), which produces DA values from 100 to 0%. Because of this, chitin is known as the biopolymer which has a DA from 100 to 40% likewise, when the chitinous biopolymer has DA lower than 40%, the biopolymer is named chitosan. Chitosan is, therefore, a biopolymer with structure very similar to that of chitin (see Figure 2) however, chitosan solubility is much greater, especially in acid mediums. 

Commercial chitin is extracted from crustacean wastes of the fishing industry, the main chitin sources being the shells of shrimp, crab, lobster, prawn and krill. These crustacean wastes consist of chitin (20-30 per cent), protein... 

Gagn, N. 1993. Production of chitin and chitosan from crustacean waste and their use as a food processing aid. 

Yang, J. K., Shih, I. L., Tzeng, Y. M., and S. L. Wang. 2000. Production and purification of protease from a Bacillus subtilis that can deproteinize crustacean wastes. Enzyme Microb. Technol. 26 406-413. 

Carotenoids were originally supplemented to salmonids in the form of crustacean waste. More recently, synthetic canthaxanthin and astaxanthin have been fed separately or in combination (Torrissen, 1989). Torrissen et al. (1990) reported that when either of these carotenoids were fed at 35-75 mg/kg diet, this resulted in salmon that contained approximately 6 mg pigment per kg flesh when fed from smolt to marketable size. Approximately 4-5% of canthaxanthin fed is retained in salmon flesh retention in rainbow trout Oncorhynchus my kiss) is slightly higher at 6.5% (Hardy etaL. 1990). In addition, rainbow trout are pigmented faster... 

Tokuyama Bay, Japan, received 6.6 metric tons of mercury wastes between 1952 and 1975 in wastewater from two chloralkali plants, although sediment analysis suggests that as much as 380 tons of mercury were released (Nakanishi et al. 1989). Unlike Minamata Bay, however, there were no human sicknesses reported, and the hair of residents contained 0 to 5 mg Hg/kg FW vs. 15 to 100 mg Hg/kg FW in Minamata residents. In 1970, a maximum concentration of 3.3 mg total Hg/kg FW was reported in tissues of Squilla, a crustacean. In 1973, a health safety limit was set of 0.4 mg total Hg/kg FW in edible fish and shellfish tissues with a maximum of 0.3 mg methyl-mercury/kg FW permitted at least five species of fish had more than 0.4 mg total Hg/kg FW, and fishing was prohibited. Contaminated sediments (>15 mg total Hg/kg) were removed by dredging and reclamation between 1974 and 1977. By 1979, the mercury content of all fish, except one species, was less than 0.4 mg total Hg/kg FW fishing was prohibited. By 1983, all fish and shellfish contained less than 0.4 mg Hg/kg FW and fishing was allowed (Nakanishi et al. 1989). 

American lobster, Homarus americanus serum Marine crustaceans Muscle, 10 species Whole, various species Aesop shrimp, Pandalus montagu r, soft parts Scotland reference site vs. waste dump site Caribbean spiny lobster, Panulirus argus soft parts Puerto Rico Anasco Bay West coast... 

Waste water treatment chitosan/ drugstore deacetylated diitin chitin of crustaceans, also fixmd in insects and fimgi... 

Shell wastes from shrimp, crab, and lobster processing industries are the traditional source of chitin. However, commercial production of chitosan by deacetylation of crustacean chitin with a strong alkali appears to have limited potential for industrial acceptance because of seasonal and limited supply, difficulties in processing, particularly with the large amount of waste of concentrated alkaline solution causing environmental pollution, and inconsistent physico-chemical properties (Chatterjee et ah, 2005). 

Three bioassays a) 48h and 96h acute crustacean test (Daphnia pulex) b) 96h acute fish test (Oncorhynchus mykiss and Oncorhynchus nerka) c) residual oxygen fish test (Oncorhynchus mykiss and Oncorhynchus nerka) Municipal solid waste (MSW) leachates originating from a) Landfills b) Laboratory lysimeters (downward) c) Field lysimeters (downward) Unspecified pretreatment... 

Four bioassays a) 5 min acute bacterial test (Vibrio fischeri) b) 11 to 21 d algal test (Pseudokirchneriella subcapitata) c) 48h acute crustacean test (Daphnia magna) d) 96h acute fish test (Pimephales promelas) Municipal and industrial solid waste leachates originating from a sanitary landfill Filtered (glass fiber and 0.45 pm membrane filters for algal test) and unfiltered... 

Chronic exposure micro-crustacean toxicity tests (7-d Ceriodaphnia dubia test 21-d Daphnia magna test) are relevant as well for evaluation of waste leachates. The major differences between these two assays have been discussed elsewhere (Ferard and Ferrari, 1997). For WASTOXHAS applications, we tend to favor the former over the latter for the following reasons ... 

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