Algae production on pig sludge

Abstract

This report shows that pig manure can be used for algal production in small farms. Huge pig sludge amounts produced using actual methods in large-scale pig breeding farms is a major issue due to the lack of disposal options and potential water pollution. This issue may be solved by using pig sludge for algal biofuel production. Therefore, we studied an economical method of algae production on pig sludge that can be operated on animal farms in Hungary with modest levels of investment. We analyzed four algae species, Chlorella vulgaris, Scenedesmus quadricauda, Scenedesmus dimorphus, and Arthrospira platensis, in the laboratory and C. vulgaris in outdoor conditions. The following parameters were studied: pot size, illumination, temperature, filtered versus unfiltered pig manure, water depth, aeration, CO 2 enrichment, inoculums solution, fertilization level, and length of rotation period. Produced alga biomass was measured every 4 days, and the protein-and lipid content was analyzed using the method of Bradford (1976) and Erickson (1993). Our results show first that the unfiltered pig manure is not suitable for algae production due to illumination shortage. By contrast, using filtered pig manure, we found that C. vulgaris yield in 70-l indoor pots was 64% higher than in smaller pots. In a larger outdoor system, the annual dry yield of C. vulgaris reached 141-259 t/ha during 12-day-long rotation periods. Here, we demonstrate that only filtered liquid pig manure can be recommended for algae production. C. vulgaris is the most suitable alga species for use in large-scale experiments on pig sludge. Based on our outdoor experiments, the adaptation of a 12-to 14day rotation period could be considered the most reasonable. An algae farm can therefore be operated with relative modest amount of capital, can hence address the issue of sludge management, and provide a substrate for energy production.

Scenedesmus quadricauda for Nutrient Removal and Lipid Production in Wastewater

“…However, algal biodiesel technology is still immature for full-scale commercialization (Craggs et al, 2012). In addition to biodiesel production, certain species of microalgae can successfully remove nutrients from highly polluted wastewater containing excess nitrogen and phosphorus (Bai et al, 2012;Li et al, 2011;Wang et al, 2010). Moreover, an increased emphasis has been placed on the simultaneous use of different species or combinations of microorganisms in wastewater treatment (Bilanovic et al, 2009;Craggs et al, 2012;Da Rosa et al, 2011).…”

Rethinking sustainable biofuel marketing to titivate commercial interests

“…Microalgae cells have a very short harvesting cycle ( $ 14-16 days considered optimum) compared to other feedstock. Microalgal harvesting could be performed at multiple cycles to provide enough biomass supplies to meet bioethanol production demands [20,29]. 3.…”

“…During harvesting, the biomass is concentrated to 10-20% while at the dewatering stage it is further concentrated to about 80%. Culture harvesting is performed when the stationary growth phase is reached and it is usually reported around 14-16 days after inoculation [29]. Hence, continual harvesting at the same phase of microalgae growth would ensure a relatively constant composition of microalgae culture and biomass concentration [37].…”

The Significance of Forests and Algae in CO2 Balance: A Hungarian Case Study

“…In this way a considerable reduction in emissions is possible. In addition, algae can even be substituted for diesel oil with a more positive effect on the CO 2 balance [3,[13][14][15][16], and the waste heat from electricity generation is another aspect of algae production. Regarding the long-term importance of algae in CO 2 sequestration, the possible effects of two algae species (Chlorella vulgaris and Scenedesmus dimorphus) produced near power plants are included in our analysis by using some of the results from our previous experiments [16].…”

“…Forests and algae both have very favorable and similar CO 2 sequestration potential (in average 1.78 kg/kg/year and 1.6-2 kg/kg/year dry material, respectively), and high yields (forests: 2.6-3.9 t/ha/year; algae: 127-250 t/ha/year). In addition, algae can even substitute other fossil fuels (in our calculations this would be diesel oil) with a more positive effect on the CO 2 balance [3,[15][16][17][18], as detailed later. It should be mentioned that these crops also produce CO 2 emissions but this is a non-fossil type of emission so it does not add to the global CO 2 balance.…”