Epuration biologique du lisier de porc par production de biomasses d'algues unicellulaires

Microalgae and wastewater treatment

Organic and inorganic substances which were released into the environment as a result of domestic, agricultural and industrial water activities lead to organic and inorganic pollution. The normal primary and secondary treatment processes of these wastewaters have been introduced in a growing number of places, in order to eliminate the easily settled materials and to oxidize the organic material present in wastewater. The final result is a clear, apparently clean effluent which is discharged into natural water bodies. This secondary effluent is, however, loaded with inorganic nitrogen and phosphorus and causes eutrophication and more long-term problems because of refractory organics and heavy metals that are discharged. Microalgae culture offers an interesting step for wastewater treatments, because they provide a tertiary biotreatment coupled with the production of potentially valuable biomass, which can be used for several purposes. Microalgae cultures offer an elegant solution to tertiary and quandary treatments due to the ability of microalgae to use inorganic nitrogen and phosphorus for their growth. And also, for their capacity to remove heavy metals, as well as some toxic organic compounds, therefore, it does not lead to secondary pollution. In the current review we will highlight on the role of micro-algae in the treatment of wastewater.

Dynamics of industrial waste stabilization pond treatment process

Waste stabilization pond is an artificial ecosystem; its performance is governed by the nature of the biological communities it supports. These are primarily used as secondary effluent treatment plants to polish the effluents. However, they are also used to treat the raw sewage and industrial effluents. In the present study, the functioning of a waste stabilization pond system from an industrial complex located in Goa was taken up. The raw waste released by the industrial complex and the final effluent released from the stabilization ponds were analyzed for pH, dissolved oxygen (DO), biological oxygen demand, phosphate content, chlorophyll content, and algal diversity and density. Also, the activities of the enzymes catalase and phosphatase were measured. The study was carried out for a period of 1 year and the data covering pre-monsoon, monsoon, and post-monsoon seasons are tabulated. The study revealed that DO, chlorophyll content, and algal count were maximum during pre-monsoon when compared to monsoon and post-monsoon. Similarly, maximum enzymatic activity was recorded during pre-monsoon and also maximum removal of biological oxygen demand and phosphate was recorded during this period than in monsoon and post-monsoon.

The potential of microalgal biotechnology: A review of production and uses of microalgae

An overview of the various aspects, promises and limitations of microalgal biotechnology is presented. The factors of importance in microalgal cultivation as well as the culture systems are briefly described. Microalgal biomasses can fulfil the nutritional requirements of aquatic larvae and organisms. The biochemical composition of algae can be improved by the manipulation of culture conditions. The nutritive value of the microalgal biomasses for human and animal consumption is also commented upon as well as some socio-economical aspects. Among the sources of required nutrients (N, P), wastewaters and manures can upgraded as culture media for microalgae the safety of which has to be evaluated. Harvesting of the biomass is one of the bottlenecks. The various techniques, physical, physico-chemical and biological are outlined and their feasibility and economic interest examined. Microalgal biomasses can be submitted to various technological transformations. Various processes are reviewed in the light of their effects on safety and nutritional value. The possible extraction of fine chemicals and the preparation of protein concentrates is also reported on. The various uses of microalgae lead to a possible competition, to be evaluated, between systems for the production of food, energy and chemicals. The review finally covers the application of genetic manipulation to microalgae.