WORKS PERFORMED IN THE FIELD OF SOLID AND LIQUID WASTES

Wastes and waste waters from the food processing were studied in such a way that the process could give a product with an added value. All the processes developed were efficient and could have a safe application and give the security to the consumer. Biotransformation of solid wastes from the food industry and other sources may constitute a very interesting approach to alleviate the problem of feed ingredients shortness in all the Arab countries. This way is very advantageous for prevention of discarding solid wastes in the nature and may constitute an important component for the durable development.

SOLID WASTES

Fish wastes

Fish wastes are produced in huge quantities in Morocco and other Arab countries. Only part of these wastes is transformed into fish meal by a drying process. The fish meal process cannot be applied in small plants because of the equipment and energy cost, and even if it is used in large scale production plants, it cannot treat all the waste quantities. The energy consumption of the drying process may increase the price of the fish meal and consequently the price of the feed made of this ingredient.
Fish wastes were first investigated to know their chemical and microbiological characteristics [ Scientific publications ]. By the same way, strains of lactic acid bacteria were screened on fish waste supplied with molasses to select the suitable combinations for the fish silage fermentation. Physico-chemical and microbiological determinations were followed up during the fermentation process.
The fermentation was monitored and controlled by studying deeply the fish waste fermentation process. The chemical profiles and the microbiological patterns were followed up during the fermentation process.
Our studies were directed to an added value product because of the nature of the waste which is a very interesting material by its chemical composition. A pilot scale fermentation was carried out and the obtained product was feed to broilers. The safety was demonstrated and the process was completed. This process was [ patented ]

Slaughterhouses solid wastes

Slaughterhouses (poultry and animals) by-products and wastes can be improved and transformed by biotechnological techniques. These solid materials were supplied with molasses and their pH adjusted with sulfuric acid to be inoculated with selected strains of lactic acid bacteria for a biopreservation process. Microbial profiles pattern showed a net decrease for coliforms and Clostridium in all the trials. Salmonella was not detected in any trial and lactic acid bacteria growth showed a normal pattern so the strains were not influenced by the environmental and nutritional factors in the fermentation system .
Fermentation by suitable lactic acid bacteria strains may also ensure the safety of the obtained product with regard to hazardous and/or toxigenic microorganisms. It is assumed that lactic acid bacteria have a role in the biopreservation of foodstuffs. Our Research on the recycling of organic wastes is now focused on a low cost-safe-process rather than high cost/high risk process such as drying. The fermentation process by suitable microorganisms would lead to preventing problems related to animal feeding. (see Kherrati et al 1997 ) and ( Ouhssine et al 1997 )

Gut dressing works

Slaughterhouses are also involved indirectly in the generation of other solid wastes. Therefore, the gut dressing works are usually done in the slaughterhouses or in small units near them. The gut dressing works may discard huge amounts of solid wastes which are driven by the washing waters to the natural water streams or to the sea when the town is coastal. In many cases these solid wastes are discarded with waste waters in the urban waste water collectors. Studies are now being carried out on the treatment of these wastes and how to use them as a source of proteins for animal feeding because of the interesting chemical composition. The same process was applied also to these materials in fermentation system. The results are brought out in the paper and which show a very interesting finding in the field of solid wastes treatment and recycling (see El mjadli et al 2000).
When not treated, the gut dressing works solid materials are the most polluting animal wastes. These materials are highly contaminated with the organic matter as well as enzymes such as proteases originated from the intestines, but when they are suitably recycled they must constitute a very interesting source of proteins and enzymes which can be exploited in the feed industry.

Poultry Wastes

1- Poultry offals

Poultry by-products or offals from poultry slaughterhouses are produced in huge amounts throughout the world. The high production and consumption of poultry may generate large amounts of the solid by-products. Poultry by-products (offals), poultry wastes (manure) and poultry feathers were investigated by several workers. Formic acid for the hydrolysis of poultry slaughterhouse offals and wastes to make a preparation for feeding pigs was used.
Poultry offals can be dried and used as proteins source in feed formulations. This procedure may require a high cost equiment and materials and can not treat all the amounts produced in a short time to prevent microbial growth in the offals. Other procedures to transform and preserve these offals are still being studied and the biotechnological techniques would be more suitable for the low cost and also for the easy handling of the by-products. Moreover, the obtained products from biotransformation could be more safe and more interesting for the nutrition to be used in feed formulations. Hence, products obtained from animal offals and/or by-products by appropriate biotechnological methods need to be investigated more deeply for accurate data on nutrition and probiotic activities.
Products obtained from animal offals and/or by-products by biotechnological methods are to be investigated more deeply for more data on nutrition and probiotic activities. Preservation and/or transformation of poultry by-products can use a biotechnological process which do not require sophisticated equipment and complicated techniques.
Our investigations focused on poultry offal transformation and preservation by fermentation using selected strains of lactic acid bacteria. Poultry slaughterhouses wastes or by-products were supplied with molasses in the ratio 90:10 and inoculated with strains of Lactobacillus plantarum to study the biopreservation process by fermentation. All the trials were carried out in triplicates and analyzed before and during the transformation (8 days) for their microbiological and physico-chemical determinations. The formers included plate counts, coliforms, Salmonella, Clostridium and yeasts and the laters included also the pH and the total volatile nitrogen. Results concerning the microbiological evaluations showed that the samples were highly contaminated. Coliforms reached 7.10⁵ cfu/g, the plate counts were also from 8x10⁶ to 4x10⁸cfu/g and Clostridium counts ranged from 1x10² to 4x10² cfu/g. Biotransformation assays yielded a rapid pH decrease and a drastic decrease in coliforms and Clostridium counts in all the trials. Salmonella was not detected in any trial. An increase in yeast populations was also observed in all the trials. The quality of the obtained product was characterized by the total volatile nitrogen which decreased during the fermentation and stopped at the end of the process indicating a good preservation of the product.

2- Poultry manure

The huge production of poultry wastes led to intensive research in the field of waste recycling and bioengineering aspects of this solid-waste treatment. In the recent years, poultry manure has been used, directly or after transformation by chemical (acidification) or physical (heating) processes, in feed formulations. The treated material was used in low concentrations in feeds. However, the use of biotechnological processes in the field of waste recycling and transformation can be a good way to ensure the safety of the obtained product, which are now qualified as «bio-products ».
Many tentatives to develop suitable methods for the treatment of poultry waste were described. Chemical acidification by acetic acid, propionic acid or a mixture of both was also used to eliminate pathogens and formaldehyde was also tried for reducing the undesirable microorganisms. Several papers have been given on the biological fermentation or ensilage of poultry manure. However, none of these methods used a controlled fermentation by pure cultures of lactic acid bacteria.
Poultry wastes include the excreta of poultry and parts of feed and other subsequent materials such as feathers and beeding. These materials are produced in high amounts through out the world and would constitute a cheaper source of proteins for the developing countries if appropriately transformed and/or preserved. Several methods and procedures were applied to preserve and to transform these wastes into usable materials in feeds or as substrates for the production of organic fertilizers.
The need for animal feeds is increasing more and more due to the animal and poultry growing increase. The agricultural crops to be used in animal feeds are in shortness. So, to balance the lack of protein sources, a part of animal wastes can be used at least partly in feed formulation. The usual techniques including drying and/or chemical treatments (formol, acidifying etc..) are not safer and can induce other problems to the animals and/or to the consumer
New techniques using biotechnological processes are more interesting for the control of food and feed systems. Not only are these wastes preserved but they are also transformed into a new ingredient. The use of lactic acid bacteria would have a natural inhibiting activity on the undesirable microflora in wastes which would result in a natural preservation and the biotransformation technology can be monitored in such a way that the ingredient is safer.
Poultry wastes (manure), collected from different poultry farms were first characterized microbiologicaly by standard plate count and counts of coliforms, Clostridium, enterococci and Salmonella. Procedures for inhibiting the undesirable microorganisms by a biological process was carried out by the use of lactic acid fermentation. The strains used belong to Lactobacillus plantarum and Pediococcus sp which were inoculated to diluted poultry wastes. The wastes (caged laying hen excreta) were diluted by adding the same amount of distilled water (1:1) and inoculated with a 5 % (v/v) of a 48 hours starter culture. The different microbial groups were followed for 15 days. Results indicated that the wastes were highly contaminated with hazardous microorganisms. Coliform counts ranged from 5x10⁶ to 6x10⁸ cfu/g, enterococci counts were also high and reached 2.4x10⁸ cfu/g, Clostridium levels were around 80 -200 cfu/g and the standard plate count varied between 8x10⁷ and 4x10⁹. All these microbial populations were drastically reduced by the fermentation process. The pH was decreased to 4.01 and the growth curve of the starter culture (lactic acid bacteria) showed a typical pattern for a successful growth. The total volatile nitrogen was also decreased to lower values (0.1 %) in the fermented product.

LIQUID EFFLUENTS

Olive Mill Waste Waters

Olive mill waste (OMW) waters are produced in huge amounts in all the olive producing countries. These efluents are still discarded in natural water streams or collected in pits near the olive mill in the case of Morocco. OMW waters are highly contaminated with polyphenols which may render the effluent hard to treat by usual biological processes because of the inhibiting action on the microorganisms responsible of the organic matter decomposition.
In our first study (see paper 6), we demonstrated that the microbiota of OMW waters is made of yeasts and moulds. These microorganisms may survive or grow in presence of a high concentrations of polyphenols. The use of OMW waters as a medium for yeast cultures was not investigated enough to improve the growth and consequently the biomass production.
In a second step, olive mill waste waters were supplied with 2 % urea and inoculated with yeast strains. Strains were screened for their biomass production, COD reduction and polyphenols bioconversion activities. Pure cultures of yeasts were realized and biomass production, COD (chemical oxygen demand) reduction and Polyphenols bioconversion were followed up in the inoculated OMW waters. Results showed that the urea supply improve significantly the biomass production relatively to the control. Polyphenols removal was estimated to around 50 % and the COD was decreased from 54.14 g/kg to 21.56 g/kg. This aerobic treatment leads to a valorization of the effluent.
In a third step, the removal yield of polyphenols reached 95 % by immobilized moulds on a solid material. The white rot mould was immobilized on chitin by growing the mould on enriched chitin with olive mill waste waters until growth was heavily observed and the material was filled into a column. The olive mill waste waters was then circulated in the column at a constant rate. Our research is continuing on these effluents for the research of a total process for the treatment.

CONCLUSION

The biotransformation of wastes by fermentaiton may constitute a very convenient process for the recycling of the huge amounts of wastes lost every day in the different food treating units (industries, slaughterhouses etc.). The process may allow the obtention of products with added values. The innovative research carried out in the present work may lead to the recycling of the large amounts of biomass discarded in the nature. The process may allow the prevention of solid wastes pollution and may also enhance these wastes by transforming them into usable ingredients.
Biotransformation and/or biopreservation is now being more and more used for several food and feed systems as well as for wastes treatments. These techniques are not new to man since fermentation had been used before the discovery of microorganisms. In fact, techniques for preserving foods involve salting and drying (olives pickles, meat, dairy and fish products). All the biological processes involving fermentation are almost similar and the most important points in the occurrence of fermentation are:
- Inhibition of undesirable microorganisms in the product.
        Hazardous species (safety)
        Spoilage species (preservation)
- Transformation of some compounds to improve the nutritional quality.
- Stabilization and preservation of the material.
These properties are due mainly to lactic acid bacteria naturally present in the raw material or brought out as pure starter cultures and which may resist high salt concentrations and overgrow the other microorganisms during fermentation at relatively low temperatures (30°C).
The activity of lactic acid bacteria in the fermentation is complex but the main metabolism would lead to the production of organic acids (lactic acid), aroma compounds and bacteriocins. All the properties occur naturally in some fermented foods and the self-preservation is due to the activity of these microoganisms.
Moreover, the fermentation by suitable lactic acid, bacteria strains may also ensure the safety of the obtained product with regard to hazardous and/or toxigenic microorganisms. It is assumed that lactic acid bacteria have a role in the biopreservation of foodstuffs. Our Research on the recycling of organic wastes is now focused on a low cost-safe-process rather than high cost/high risk process such as drying. The fermentation process by suitable microorganisms would lead to preventing problems related to animal feeding.
The preservation and/or stabilization of wastes by fermentation is a new way for recycling or enhancing these materials. These techniques are simple and could be applied in all the countries.