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[Display omitted] • Solids and nutrients in raw swine wastewater were removed with 3-step pretreatment. • Better S. dimorphus growth was achieved in pretreated than raw swine wastewater. • Algal reactors showed no consistent wastewater treatment boost versus control. • Algae-rich solids harvested from pretreated wastewater contained 5.7% nitrogen. • S. dimorphus is unlikely a suitable microalgal species for phosphorus recovery. Scenedesmus dimorphus was cultivated in raw and pretreated swine wastewater (SW) with 6-L photobioreactors (PBRs) to investigate the effect of solid–liquid separation on algal growth. The same aerated PBRs containing no algae were used as control. Moderate COD and nitrogen removal from the SW was achieved with the algal PBRs. However, compared to the control reactors, they offered no consistent treatment boost. Improved algal growth occurred in the pretreated SW, as measured by maximum algal cell count (3202 ± 275 × 106 versus 2286 ± 589 × 106 cells L−1) and cell size. The enhanced algal growth in the pretreated SW resulted in relatively high nitrogen (5.7 %) and organic matter contents in the solids harvested at the end of cultivation experiments, with ∼25.6 % of nitrogen in the SW retained in the solids and ∼9.1 % absorbed by algae. The pretreatment also resulted in elevated phosphorus removal. This study is anticipated to foster the development of microalgae-based SW treatment processes. [ABSTRACT FROM AUTHOR]

Particulate matter (PM) represents an air quality management challenge for confined swine production systems. Due to the limited space and ventilation rate, PM can reach relatively high concentrations in swine barns. PM in swine barns possesses different physical, chemical, and biological characteristics than that in the atmosphere and other indoor environments. As a result, it exerts different environmental and health effects and creates some unique challenges regarding PM measurement and mitigation. Numerous research efforts have been made, generating massive data and information. However, relevant review reports are sporadic. This study aims to provide an updated comprehensive review of swine barn PM, focusing on publications since 1990. It covers various topics including PM characteristics, sources, measurement methods, and in-barn mitigation technologies. As PM in swine barns is primarily of biological origins, bioaerosols are reviewed in great detail. Relevant topics include bacterial/fungal counts, viruses, microbial community composition, antibiotic-resistant bacteria, antibiotic resistance genes, endotoxins, and (1→3)-β-D-glucans. For each topic, existing knowledge is summarized and discussed and knowledge gaps are identified. Overall, PM in swine barns is complicated in chemical and biological composition and highly variable in mass concentrations, size, and microbial abundance. Feed, feces, and skins constitute the major PM sources. Regarding in-barn PM mitigation, four technologies (oil/water sprinkling, ionization, alternation of feed and feeders, and recirculating air filtration) are dominant. However, none of them have been widely used in commercial barns. A collective discussion of major knowledge gaps and future research needs is offered at the end of the report. [ABSTRACT FROM AUTHOR]

The continual consolidation and concentration of animal feeding operations (AFOs) raises various environmental challenges, including air pollutant emission. Cost-effective mitigation technologies are pursued to protect the health and wellbeing of animals and farmers as well as the environment. Previous lab studies utilized ammonia (NH 3) and carbon dioxide (CO 2), two major air pollutants in AFOs, for microalgal cultivation. However, the field performance of this algae-based mitigation approach has yet to be investigated. In this study, two photobioreactors (PBRs) were tested in a nursery pig barn to mitigate NH 3 and CO 2 while growing Scenedesmus dimorphus (S. dimorphus). Pit air was fed into the PBRs where the two pollutants were adsorbed by S. dimorphus as nutrients to produce algal biomass and oxygen gas (O 2). The cleaned air then recirculated back to the room space. S. dimorphus reached its maximum cell count on the 17th day of the experiment when NH 3 and CO 2 concentrations in the pit air were 25.6 ppm and 3150 ppm, respectively. The maximum biomass concentration occurred on the 11th day when the NH 3 and CO 2 concentrations were 14.6 and 2250 ppm, respectively. The average mitigation efficiency was 31–50% for NH 3 and 1–1.7% for CO 2. The costs for removing 1 g NH 3 and CO 2 were estimated to be $3.77 and $0.20, respectively. This study shows that an integrated PBR system is technically feasible for reducing pig barn air pollutant emission while producing microalgae as a valuable product. [Display omitted] • Scenedesmus Dimorphus was cultivated with the pit air in a pig barn. • ∼31–50% NH 3 and 1–1.7% CO 2 were captured and converted into algal biomass. • Even with incoming NH 3 , the medium pH stayed 6.8–7.0 requiring minor adjustment. • The highest cell count and algal biomass were 14.9 x 106 cells mL−1 and 0.892 g L−1 [ABSTRACT FROM AUTHOR]