Efficient nutrient removal from swine manure in a tubular biofilm photo-bioreactor using algae-bacteria consortia

Abstract

Concentrated animals feeding operations (CAFOs) often pose a negative environmental impact due to the uncontrolled spreading of manure into soils that ends up in the release of organic matter and nutrients into water bodies. Conventional aerobic methods treating CAFOs wastewater require intensive oxygenation, which significantly increases the operational costs. The alternative proposed in this research is the application of micro-algae based systems by taking advantage of the cost-effective in situ oxygenation via photosynthesis. A 4.9 L enclosed tubular biofilm photo-bioreactor was inoculated with an algal-bacterial consortium formed by the micro-algae Chlorella sorokiniana and a mixed bacterial culture from an activated sludge process. C. sorokiniana delivers the O(2) necessary to accomplish both organic matter and ammonium oxidation. The reactor was fed with diluted swine wastewater containing 180, 15 and 2,000 mg/L of NH(4) (+)-N, soluble P and total COD, respectively. The photo-bioreactor exhibited good and sustained nutrient removal efficiencies (up to 99% and 86% for NH(4) (+) and PO(4) (3-), respectively) while total COD was removed up to 75% when the biofilm was properly established. Liquid superficial velocities up to 0.4 m/s (achieved by culture broth recirculation) hindered the formation of a stable biofilm, while operation at velocities lower than 0.1 m/s supported stable process performance. The high shear stress imposed by the centrifugal recirculation pump disintegrated the large aggregates detached from the biofilm, which resulted in a poor settling performance and therefore poor COD removal efficiencies. Enclosed biofilm photo-bioreactors therefore offer a potentially more economical alternative to conventional tertiary treatments process.

Advanced nutrient removal from surface water by a consortium of attached microalgae and bacteria: A review

“…Enclosed tubular photobioreactor such as the Spiral Periphyton Bioreactor (SPR) by Shangguan et al (2015) and the tubular biofilm photo-bioreactor by Muñoz and co-workers (Gonzalez et al, 2008;De Godos et al, 2009) are novel configurations for the removal of various kinds of pollutants using the attached microalgae-bacteria consortium. The unique spiral structure can prolong the contact time of water with the consortium in limited spaces and allows a compact photobioreactor design.…”

Scenario Analysis of Nutrient Removal from Municipal Wastewater by Microalgal Biofilms

“…Removal capacities over 90% were measured for ammonium (NH 4 + ), nitrate (NO 3 − ) and over 80% for phosphate (PO 4 3− ) [12][13][14], and up to 75% of the Chemical Oxygen Demand (COD) was removed from diluted swine manure in an algal-bacterial biofilm [14]. However, the feasibility of the application of microalgal biofilms in wastewater treatment will be determined by more factors than the removal capacity.…”

Phosphorus Removal and Recovery from Digestate after Biogas Production

“…Pretreatment steps like dilution to avoid inhibition and sterilization to prevent the contamination may be required for certain algae systems [121]. Raw and anaerobically digested swine manure has been treated widely by (1) suspended algae in (i) high rate pond systems [128][129][130][131], (ii) mixed algae systems [132] and (iii) mixed algae-bacterial systems [133] or (2) by immobilized algae [120], e.g., algal turf scrubber units [134][135][136]. The harvested algae can be a good high-grade protein supplement for animal feed and also can be used as a slow-release fertilizer [136] which can be directly sprayed as suspension in farm land or stored for future use [137].…”