Treatment of swine manure effluent using freshwater algae: Production, nutrient recovery, and elemental composition of algal biomass at four effluent loading rates

Abstract

Cultivating algae on nitrogen (N) and phosphorus (P) in animal manure effluents presents an alternative to the current practice of land application. The objective of this study was to determine how algal productivity, nutrient removal efficiency, and elemental composition of turf algae change in response to different loading rates of raw swine manure effluent. Algal biomass was harvested weekly from laboratory scale algal turf scrubber units using four manure effluent loading rates (0.24, 0.40, 0.62 and 1.2 L m −2 d −1 ) corresponding to daily loading rates of 0.3-1.4 g total N and 0.08-0.42 g total P. Mean algal productivity values increased from 7.1 g DW m −2 d −1 at the lowest loading rate (0.24 L m −2 d −1 ) to 9.4 g DW m −2 d −1 at the second loading rate (0.40 L m −2 d −1 ). At these loading rates, algal N and P accounted for > 90% of input N and 68-76% of input P, respectively. However, at higher loading rates algal productivity did not increase and was unstable at the highest loading rate. Mean N and P contents in the dried biomass increased 1.5 to 2.0-fold with increasing loading rate up to maximums of 5.7% N and 1.8% P at 1.2 L m −2 d −1 . Biomass concentrations of Al, Ca, Cd, Fe, K, Mg, Mn, Mo, Si, and Zn increased 1.2 to 2.6-fold over the 5-fold range of loading rate. Biomass concentrations of Cd, K, Pb, and Si did not increase significantly with loading rate. At the loading rate of 0.40 L m −2 d −1 (corresponding to peak productivity) the mean concentrations of individual components in the algal biomass were (in mg kg −

Assessment of Heavy Metal Contamination of Agricultural Soil around Dhaka Export Processing Zone (DEPZ), Bangladesh: Implication of Seasonal Variation and Indices

“…The three freshwater algae are cosmopolitan genera from freshwater systems and are therefore representative of the macroalgae available in many freshwater environments. Furthermore, all can have rapid growth, particularly under eutrophic conditions, and are pest species in these environments [27,28,29,30,31,32]. These algae range from the unbranched filamentous Oedogonium (cell diameter .2 mm) and Rhizoclonium (cell diameter .10-50 mm) to the net-forming Hydrodictyon (water net).…”

Recovery of Protein Concentrates From Microalgal Biomass Grown in Manure for Fish Feed and Valorization of the By-Products Through Anaerobic Digestion

“…In this context, microalgae biomass grown using PM is usually rich in ash (Kebede-Westhead et al, 2006). This ash content decreases feed digestibility, which affects to the optimal health and development of the fish.…”

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].…”