CHARACTERIZATION AND ANAEROBIC TREATMENT OF BIOLOGICAL AND PHYSICOCHEMICAL SLUDGE FROM A MOROCCAN DAIRY INDUSTRY

Abstract

The physicochemical and biological sludge (PCS and BS) from a Moroccan dairy industry, constitute a source of organic matter that is ranging respectively between 58.67 to 90.6% and 18.85 to 92.5%. The composition of these sludges is very specific because they are derived from an effluent mixture (milk, orange, whey, …) witch varied according to production of this industry. As results, the physicochemical and microbiological characteristics of these sludges fluctuate according to time. The pH of biological sludge varied between 7.35 to 8.85 while the pH of physicochemical sludge fluctuated between 5.32 to 7.5. In addition the microbial germs is represented by total coliforms (3.95.107 and 2.02.1011UFC.ml-1), total germs (1.61.109 and 2.36.1012 UFC.ml-1), sulphate-reducing bacteria (1.55.108 and 5.72.109 UFC.ml-1), lactobacillus (2.15.108 and 9.37.1011 UFC.ml-1) and streptococcus (1.05.109 and 2.46.1011UFC.ml-1) (respectively for BS and PCS). Assessment of anaerobic digestion for treating these wastes in batch reactor at mesophilic condition (38°C) show the promising results in terms of methane production and organic pollution removal. Indeed, the methane yields were 5.601 and 20.79 mlSTP.gVS-1 gave respectively by BS and PCS for the maximal load (100% of substrate) which is the optimal load. The total solid and volatile solid reduction reached 79.63 and 83.60% for biological sludge while it reached 87.06% and 89.16% for physicochemical sludge for the same load (100% of sludge).

Keywords

• biological sludge
• physicochemical sludge
• organic loads
• methane yield
• pollution removal