Anaerobic digestion of fish processing wastewater with special emphasis on hydrolysis of suspendend solids

Fish processing industries comprise an important segment of the Philippine economy. However, among other industries, they pollute lakes, rivers, and eventually, coastal waters. If their effluents are not sufficiently treated, the well-being of the country's coastal waters is threatened. In the long run, the fish industry will not be sustained because of water pollution. The prospects of generating energy from fish processing wastes will encourage factories to treat their wastewater before discharging them, and hence, may help the government in implementing strict wastewater standards.The main products of fish factories in the Philippines are canned sardines and tuna for local and foreign markets, respectively (Chapter 1). Of the weight of raw fish accepted for processing, 40-60% becomes solid waste while 1-6% goes to the wastewater streams. The wastewater produced in the canning of finfish species, e.g. sardines and mackerel, is characterized by high levels of suspended solids which are mainly proteins and lipids. The concentration of sea salts in fish-processing wastewater in the Philippines is low compared to those of factories where seawater is used in processing. The fish canneries in the Philippines use ground water in their operations. The salts in the wastewater are due to the seawater that comes with the raw material.Since fish processing wastewaters contain high concentrations of biodegradable organic matter, the potential for a net production of energy in the form of biogas is high. Hence, anaerobic treatment is an attractive option. Moreover, the excess sludge production in anaerobic processes is less than that in aerobic processes. High-rate anaerobic treatment systems are economical because they require a smaller reactor volume, and thus, are also suitable for fish canning plants having limited space for wastewater treatment. Hence, this study considers the application of high-rate anaerobic methods, e.g. UASB systems, for treating fish processing wastewater. Hydrolysis, which is generally considered as the ratelimiting step in the anaerobic digestion of insoluble organic wastes, is given special emphasis.While methanogenesis hardly affects the hydrolysis of proteins in fish, it plays an important role in complete degradation of lipids, so that environmental factors such as pH, temperature and ionic concentration must be favourable to methanogens. At high lipid levels, however, inhibition of methanogenesis by lipids will prevail and hence will inhibit their own hydrolysis. A lipid removal system prior to the high rate methanogenic reactor is advised.

Bibliographic Details

Main Author:	Palenzuela Rollon, A.
Other Authors:	Lettinga, G.
Format:	Doctoral thesis biblioteca
Language:	English
Published:	Balkema
Subjects:	anaerobic digestion, anaerobic treatment, fish culture, anaërobe afbraak, anaërobe behandeling, visteelt,
Online Access:	https://research.wur.nl/en/publications/anaerobic-digestion-of-fish-processing-wastewater-with-special-em
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