Massive amounts of (anthropogenic) organic compounds have been released into the environment by industry, generating serious issues of environmental pollution. Currently, pharmaceuticals and personal care products are known as emerging organic pollutants and are the main contaminants of concern. Among the pollutants, caffeine is one of the obstinate compounds with a noxious effect on biological systems and it is necessary to eliminate caffeine from water. Caffeine is also considered an anthropogenic indicator for contamination of surface waters. In the past few years, physicochemical (advanced oxidation process, adsorption and filtration) and biological wastewater treatment methods have been developed and extensively used for the removal of pollutants. Currently, biological treatments and nanoparticle mediated photocatalytic processes have gained popularity for the removal of caffeine with high efficiency and low capital requirement. This chapter attempts to explain the challenges, pros, cons, multifaceted operation and time consumption involved in the physicochemical and biological treatment of caffeine.

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Insect guts, particularly of phytophagous insects, are considered as intriguing bioprospecting sources of cellulase and xylanase due to their use in biofuel industry. In this study, the activities of cellulase and xylanase were identified in the gut fluid of grasshopper, Oxya velox, and characterized. Qualitative assays of gut fluid carried out for endo-β-1,4-D-glucanase (EC 3.2.1.4) and endo-β-1,4-D-xylanase (EC 3.2.1.8) activities, using substrate-agar plate method, revealed clear transparent zones against the red-stained background. When measured by dinitrosalicylic acid method, the gut fluid had 0.759 ± 0.005 U and 0.303 ± 0.002 U of endoglucanase and endoxylanase activities, respectively, per mg of protein. In the gel zymogram, four distinct cellulolytic protein bands and one xylanolytic protein band were detected against substrates carboxymethyl cellulose and xylan, respectively. The optimal temperature and pH of both endo-β-1,4-D-glucanase and endo-β-1,4-D-xylanase were 55EC and 5, respectively. Preincubation at 70EC for 20 min resulted in almost complete loss of endo-β-1,4-D-glucanase activity as shown by zymography. The presence of both cellulase and xylanase activities suggested that O. velox could be considered as a model for studying the process of lignocellulose digestion in insect gut; the insect could also serve as a good source of enzymes for biofuel production.