Mariculture wastewater treatment with Bacterial-Algal Coupling System (BACS): Effect of light intensity on microalgal biomass production and nutrient removal.

Mariculture wastewater generated from the mariculture industry has increased public concern due to its impact on the sustainability of aquatic environments and aquaculture practices. Herein, the Bacterial-Algal Coupling System was applied for mariculture wastewater treatment. Microalgae growth in heterotrophy and mixotrophy (2000-8000 lux) was first compared. The best microalgal growth and nutrient removal were obtained at 5000 lux, where biomass productivity of microalgae was 0.465 g L-1 d-1, and 98.1% of chemical oxygen demand, 70.7% of ammonia-nitrogen, and 90.0% of total phosphorus were removed. To further understand the nutrient removal through microalgae cultivation, the enzyme activities involved in the Calvin cycle and the Tricarboxylic Acid cycle at different light intensities were determined. Under mixotrophic cultivation, there was a coordination between photosynthesis and heterotrophic metabolism in the agal cell, which resulted in a high algal biomass production and removal efficiency of nutrients. This study provided a novel insight into the bioremediation of mariculture wastewater and microalgae cultivation.

Intraspecific encounters can lead to reduced range overlap.

Direct encounters, in which two or more individuals are physically close to one another, are a topic of increasing interest as more and better movement data become available. Recent progress, including the development of statistical tools for estimating robust measures of changes in animals' space use over time, facilitates opportunities to link direct encounters between individuals with the long-term consequences of those encounters. Working with movement data for coyotes (Canis latrans) and grizzly bears (Ursus arctos horribilis), we investigate whether close intraspecific encounters were associated with spatial shifts in the animals' range distributions, as might be expected if one or both of the individuals involved in an encounter were seeking to reduce or avoid conflict over space. We analyze the movement data of a pair of coyotes in detail, identifying how a change in home range overlap resulting from altered movement behavior was apparently a consequence of a close intraspecific encounter. With grizzly bear movement data, we approach the problem as population-level hypothesis tests of the spatial consequences of encounters. We find support for the hypotheses that (1) close intraspecific encounters between bears are, under certain circumstances, associated with subsequent changes in overlap between range distributions and (2) encounters defined at finer spatial scales are followed by greater changes in space use. Our results suggest that animals can undertake long-term, large-scale spatial changes in response to close intraspecific encounters that have the potential for conflict. Overall, we find that analyses of movement data in a pairwise context can (1) identify distances at which individuals' proximity to one another may alter behavior and (2) facilitate testing of population-level hypotheses concerning the potential for direct encounters to alter individuals' space use.

Integrating acidogenic fermentation and microalgae cultivation of bacterial-algal coupling system for mariculture wastewater treatment.

In this study, Bacterial-Algal Coupling System, a method integrated acidogenic fermentation (AF) and microalgae cultivation, was applied to the mariculture wastewater (MW) treatment. The MW was acidogenic fermented at different initial pH (4.0-10.0), and different dilution rate (5%-20%) of AF effluent was used for Chlorella vulgaris cultivation. The results showed that the maximum biomass production (5.6 g/L) of microalgae was obtained with 10% AF effluent. Ammonium, phosphate and volatile fatty acids could be metabolized by microalgae. More specifically, acetic acid and propionic acid were utilized prior to butyric acid and valeric acid. To better understand the synergy of heterotrophic metabolism and photosynthesis, the activities of Rubisco and citrate synthase were revealed to provide additional insight for nutrients recovery from MW by mixotrophic cultivation of microalgae.

Bacterial-algal coupling system for high strength mariculture wastewater treatment: Effect of temperature on nutrient recovery and microalgae cultivation.

In the present study, bacterial-algal coupling system, an integration process of acidogenic fermentation and microalgae cultivation was used for high strength mariculture wastewater (HSMW) treatment, resource recovery and low-cost biomass production. The effect of temperature on Chlorella vulgaris (C. vulgaris) cultivation was investigated with culture medium of acidogenic liquid. The results showed that acidogenic liquid could be used as culture medium for C. vulgaris and higher biomass was obtained compared to control. The acidogenic liquid obtained at initial pH of 8 was the most suitable culture medium for C. vulgaris growth due to befitting C/N and considerable volatile fatty acids. Moreover, the optimum temperature for C. vulgaris cultivation was 25 °C and the removal efficiency of chemical oxygen demand (COD) and NH4+-N from acidogenic liquid could reach 94.4% and 68.8%, respectively. The outcome could create an innovative value chain with environmental sustainability and economic feasibility in aquaculture industry.

Optimization of polyhydroxyalkanoates (PHA) synthesis with heat pretreated waste sludge.

To reduce the cost of polyhydroxyalkanoates (PHA) production and disposal amount of waste sludge simultaneously, the feasibility of using different heat pretreated sludge (60 °C, 80 °C, 100 °C, 120 °C) as external carbon source to synthesize PHA was examined in this study. The maximal PHA accumulation (24.1% of the dry cell weight) was achieved with 60 °C pretreated waste sludge, with the utilization efficiency of COD, proteins, carbohydrate and VFAs were 74.3%, 82.3%,47.2%,81.4%, respectively. Both of VFAs and non VFAs organics could be used as carbon source for PHA synthesis. The results of kinetic parameter analysis showed that the highest PHA production rate (0.23 mg COD/mg X·h) and the PHA conversion rate (0.46 mg COD/mg COD) all occurred when using 60 °C pretreated waste sludge. In order to further investigate the utilization of sludge carbon source for PHA synthesis, the three-dimensional fluorescence excitation-emission matrix (EEM) spectroscopy with fluorescence regional integration (FRI) analysis were introduced.