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ACETIC ACID PRODUCTION FROM MILK PERMEATE IN ANAEROBIC THERMOPHILIC FERMENTATION THÈSE N 2043 PRÉSENTÉE AU DÉPARTEMENT DE GÉNIE RURAL ÉCOLE POLYTECHNIQUE FÉDÉRALE DE LAUSANNE POUR L`OBTENTION DU GRADE DE DOCTEURE ÈS SCIENCES TECHNIQUES PAR Mylène TALABARDON – ALBESA Ingénieure de génie rural, spécialisation environnement (EPFL) de nationalité française Acceptée sur proposition du jury : Prof. P. Péringer, directeur de thèse Prof. K.L. Kovacs, corapporteur Dr. I. Marison, corapporteur Ing. B. Ryser, corapporteur Dr. J.-P. Schwitzguébel, corapporteur Prof. J. Tarradellas, corapporteur Prof. S.-T. Yang, corapporteur Lausanne, EPFL 1999 ° Acknowledgments This work was carried out at the Environmental Biotechnology Laboratory (Laboratoire de Biotechnologie Environnementale) of the Swiss Federal Institute of Technology (EPFL) from September 1996 to August 1999, supported by the Swiss Federal Office for Education and Science, in the framework of COST Action 818. First, I am grateful to Prof. Paul Péringer for giving me the opportunity and the freedom to carry out this work. I wish to express my thankfulness to Dr. Jean-Paul Schwitzguébel for providing support and advices, and allowing me to attend and present my work at many conferences in Europe and USA. I would like to thank Ing. B. Ryser with the Cremo Company for providing milk permeate during the last three years. Special thanks ...
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ACETIC ACID PRODUCTION FROM MILK PERMEATE IN ANAEROBIC THERMOPHILIC FERMENTATION THÈSE N ° 2043 PRÉSENTÉE AU DÉPARTEMENT DE GÉNIE RURAL ÉCOLE POLYTECHNIQUE FÉDÉRALE DE LAUSANNE POUR L`OBTENTION DU GRADE DE DOCTEURE ÈS SCIENCES TECHNIQUES PAR Mylène TALABARDON ALBESA Ingénieure de génie rural, spécialisation environnement (EPFL) de nationalité française Acceptée sur proposition du jury : Prof. P. Péringer, directeur de thèse Prof. K.L. Kovacs, corapporteur Dr. I. Marison, corapporteur Ing. B. Ryser, corapporteur Dr. J.-P. Schwitzguébel, corapporteur Prof. J. Tarradellas, corapporteur Prof. S.-T. Yang, corapporteur
Lausanne, EPFL 1999
Introduction 9 ___________________________________________________________________________
1 INTRODUCTION
The first chapter is a brief introduction presenting the environmental pollution problems of deicing salts used on the roads in winter and the waste disposal problems of milk permeate, important by-product of the cheese industry. The aim of the study was to find and investigate an anaerobic thermophilic fermentation process to convert lactose contained in milk permeate into acetic acid, wich could be used to produce calcium magnesium acetate (CMA), an environmentally favorable alternative deicer. 1.1 The environmental pollution due to deicing salts
The massive use of chloride salts (NaCl and CaCl 2 ) for roadway deicing, 20’000 tonnes in Vaud canton in 1998, is the cause of serious corrosion and major environmental problems. Evidence of long-term negative impacts has been documented in the literature (Labadia and Battle, 1996). These problems include deterioration of concrete bridge decks through chloride ion corrosion of reinforcing steel, corrosion of underground electrical cables, corrosion of structural members in bridge structures and other highway appurtenances; corrosion of vehicle chassis, pollution of aquatic habitats and drinking water sources by sodium and chloride ions in runoff, and harm to roadside vegetation due to an increase of the salinity of receiving waters as the sodium dissolves and to an increase of the acidity of soil and water as the chloride accumulates (Granato et al., 1995). In addition to the accelerated corrosion of automobiles, damage to concrete and asphalt, ruining of bridges, the use of sodium chloride for deicing the roads has many other drawbacks, such as adverse effects on underground cables. There are also many subtle costs of deicing with corrosive salts, for example, gasoline wasted because of slow traffic during repairs to bridges and roads, cost of transporting materials for repair, and labor and materials for replacement. For example, it is estimated that the damage done by salt is probably 12-40 times the cost of salt (for salt at roughly $30 per ton) (McCrum, 1989). The lower estimate primarily considers the corrosion damage while the higher one also takes into consideration environmental effects. Consequently, reevaluation of the conventional deicing salt has driven many scientists to seek alternative deicers. To overcome the disadvantages associated with the damaging properties of conventional deicing salts, new types of deicers have been developed that are effective, environmentally acceptable, and economically feasible. For example, calcium magnesium acetate (CMA) was introduced and identified as an environmentally favorable alternative deicer, which may lack the disadvantages shown by the conventional inorganic deicers (Winters et al., 1984; Horner, 1988; Buteau et al., 1992). CMA is produced by mixing acetic acid with calcium and magnesium oxides, dolomitic lime or dolime (Schenk, 1987). In field tests, the effectiveness of CMA has been found comparable to that of salt (Gidley, 1986; Manning and Crowder, 1987; Scheeler, 1983), without causing corrosion (Bryan et al., 1990; Schenk, 1986). CMA is also biodegradable and environmentally friendly (Schenk, 1987).
Introduction 10 ___________________________________________________________________________
Unfortunately CMA use (produced by the reaction of dolime with glacial acetic acid) has been limited by its cost ($1100/ton in 1998). Salt costs only $30/ton but when the hidden costs of road salt are included, CMA and NaCl are roughly equal in actual cost (Vitaliano, 1991). However, there is still a need to decrease CMA prices to make it a more attractive alternative; thus the cost of producing acetic acid must be decreased. Consequently, the production of acetic acid by fermentation using an economic source of material as substrate must be considered as an alternative method to produce CMA (Bryan, 1991).
Introduction 11 ___________________________________________________________________________
1.2 The environmental pollution of milk permeate
Milk permeate is an important by-product of the Swiss cheese industry, which generated an annual production estimated at 150 millions kg in 1998. Ultrafiltration (UF) of milk is frequently used for concentrating milk in several cheese producing plants (e.g., feta cheese) as well as in manufacturing special milk products. This permeate is approximately composed of 94% water and 6% solids, the latter containing mainly lactose. The milk permeate is practically free of N-compounds and thus unsuitable for animal feeding (Käppeli et al., 1981). Consequently, it is a subject of environmental concern due to its high biological oxygen demand (BOD) of approximately 50 g/L, 90 % attributed to lactose component (Kisaalita et al., 1989a). Thus, the question of milk permeate disposal/utilization is effectively a question of lactose disposal/utilization : utilizing lactose economically is crucial to the treatment of this high BOD wastewater, especially for small factories at scattered locations (Yu and Pinder, 1993). Traditional methods of whey and permeates utilization include direct animal feeding by nearby farmers (Muller, 1979), direct soil application (Watson et al., 1977), and sewage disposal (Osborn, 1979). Today, because of growing concern about environmental pollution, sewage disposal is undesirable due to the high BOD. Most recent investigations have focused on conversion to forms that are suitable for human consumption (Zadow, 1983; Teixeira et al., 1984; Gekas and Lopez-Leira, 1985) or for industrial alcohol production (Everson, 1979; Jones et al., 1993) and methane fermentation (Boening and Larsen, 1982; DeHaast et al., 1985; Kisaalita et al., 1989b; Yang and Guo, 1991). However, the production of acetic acid from milk permeate can also represent an attractive method for conversion of community waste to a community resource, with the doubled benefit of reducing waste disposal problems and environmental pollution from salts.
