Every year, close to 8 million tons of waste crab, shrimp and lobster shells are produced globally, as well as 10 million tons of waste oyster, clam, scallop and mussel shells. The disposed shells are frequently dumped at sea or sent to landfill, where they modify soils, waters and marine ecosystems. Waste shells are a major by-product, which should become a new raw material to be used to the best of their potential. There are a number of applications for waste shells in many fields, such as agriculture, medicine, chemical production, construction, environmental protection, cosmetic industry, food and feed industry, and a plethora of other (often niche) applications, which are being developed by the day. This review provides a broad picture of crustacean and mollusc shell waste management and reutilization possibilities, reviewing well established, current, and potential strategies, particularly from the standpoint of sustainability challenges and energy demand.

This study was carried out in order to establish the effects of a 6-week treatment with the diet supplemented with L. rhamnosus in concentrations of 10*7 CFU g-1 (G1 group) and 10*8 CFU g-1 (G2 group) on the condition expressed by condition factors (Fulton’s, Clark’s and B), intestinal microbiology, haematological, histological, and selected antioxidative parameters of rainbow trout. A significantly higher condition factors was found in G1 group indicating that higher concentration of probiotic (10*8 CFU g-1) did not result in the better condition. Cholesterol and urea levels were significantly higher in both G1 and G2 groups, albumin in G1 and creatinine in G2 group with respect to control. A significantly higher liver TBARS level was observed in G2 group. The feeding with supplemented probiont apparently changed the resident microbiota. Three weeks after withdrawal of the supplemented feed, the microflora mostly reverted to the control composition, although L. rhamnosus in fecal matter of fish remained inherent. The epithelial structure of the proximal and distal intestine revealed the increased absorptive area in both treated groups, as well as the increase of the mucin-secreting goblet cells. The L. rhamnosus treated groups demonstrated the capacity for the augmentation of the innate host defense