Effects of carbon dioxide addition on algae and treatment performance of high rate algal ponds : a thesis presented in partial fulfilment of the requirements of the degree of Master of Engineering in Environmental Engineering at Massey University

Waste stabilisation ponds have been used for treating a great variety of wastewaters around the world for many decades. More advanced systems combine anaerobic or advanced facultative ponds with high rate algal ponds (HRAP) followed by a number of algae settling ponds and maturation ponds to achieve enhanced and more reliable removal of wastewater pollutants, while yielding possibly valuable by-products such as biogas and algal biomass. In recent years a growing number of scientists and engineers have proposed the use of HRAP treating domestic wastewater for carbon dioxide (CO2) scrubbing from biogas and CO2 sequestration. The experiments presented in this thesis sought to determine if the treatment performance of HRAP is affected by the addition of CO2 and subsequent reduction of pond pH. Experiments with algae cultures grown on domestic wastewater in laboratory microcosms, outside mesocosms and outside pilot-scale HRAP were conducted. Carbon dioxide addition to algae wastewater cultures restricted the maximum pH level to ~8. Key wastewater quality parameters of CO2 added cultures, were compared to control cultures without CO2 addition. The wastewater quality parameters monitored include temperature, pH, and concentrations of total suspended solids (TSS), ammoniacal-nitrogen (NH4-N), dissolved reactive phosphorus (DRP), filtered biochemical oxygen demand (fBOD5) and the faecal indicator Escherichia coli (E. coli). Carbon dioxide addition to algae wastewater cultures was found to promote algal growth and increased the TSS concentrations. Over 8 day culture length CO2 addition in laboratory and outside batch experiments increased algal growth (indicated by TSS) by up to 76% and 53%, respectively. During semi-continuous outside experiments CO2 addition increased algal growth by ~20% in comparison to the control cultures. Despite enhancing algal growth (TSS), CO2 addition appeared to have little effect on algae cell morphology, species composition and zooplankton activity in the algae wastewater cultures. Monitoring of the key nutrients NH4-N and DRP in cultures with and without CO2 addition indicated that CO2 addition can lead to an increase or a decrease in nutrient removal. Under culture conditions which allowed the control cultures to achieve high day-time pH levels CO2 addition, and subsequent pH restriction, appeared to reduce overall nutrient removal. Only slight changes or an increase in nutrient removal as a result of CO2 addition were observed under culture conditions which allowed only for a moderate or small elevation of the control culture pH. However, the increases in algal biomass, observed in all CO2 added cultures indicate a greater potential for the reclamation of potentially valuable wastewater nutrients in the form of algal biomass. Monitoring of fBOD5 levels during several outside experiments showed that CO2 addition had no effect on the fBOD5 removal by the algae wastewater cultures under those conditions. During several outside batch experiments (of up to 8 day culture length) the removal of the faecal indicator bacteria E. coli was monitored. It was shown that CO2 addition reduced E. coli removal by 1.4 to 4.9 log units compared to control cultures. Basic modelling of carbon flows indicated that under New Zealand conditions the CO2 volumes required for the changes described above would be available from the biogas produced in a wastewater pond system treating wastewater with a volatile solids (VS) concentration of ~ 500 mg/L. In systems treating weaker wastewaters additional CO2 could be made available through the onsite combustion of biogas. In summary, the obtained results suggest that CO2 addition to a field-scale HRAP could increase algal biomass growth year-round and slightly enhance nutrient removal during winter, but might reduce nutrient removal during summer, and reduce E. coli removal year-round, while having no effect on fBOD5 removal. The reduction in nutrient treatment performance during summer, and especially the losses in E. coli removal resulting form CO2 addition may require more sophisticated downstream processing of the HRAP effluent, like increase retention times in maturation ponds. Such remedial measures have to be evaluated on a case by case basis, and are dependent on the given regulations and discharge regimes of the system. This study indicates that in general HRAP can be employed for biogas purification and provide a useful sink for CO2 rich waste streams. The beneficial effects of CO2 addition to HRAP do not appear to allow for any design or management changes within the system, while it was indicated that most detrimental effects of CO2 addition could be accommodated without major alternations, although in some cases significant remedial measures may be required for correcting the losses in disinfection and nutrient removal performance

Incentive Contracts in Team Sports - Theory and Practice

A comparison of incentive clauses of players’ contracts in German soccer and clauses used in the NFL and NBA shows considerable differences. Against the background of principle-agent theory we have a closer look at these incentive systems. In contrast to other industries it is easy to observe the employees’ effort in team sports. Therefore, it would be desirable to set incentives for players based on their individual effort. We show that there are reasons why incentive clauses in professional German soccer, the NBA and the NFL are not directly based on effort. We argue that there are two main reasons: Firstly, efficient incentives are complementarily provided by subjective and objective performance measures. Secondly, cooperation amongst team members is essential in team sports.sports, labor contracts, agency theory, incentives,

Low-cost filter media for removal of hydrogensulphide from piggery biogas

The presence of elevated concentrations of hydrogen sulphide (H2S) in piggery biogas is problematic due to its corrosiveness and toxicity. At small scale, the cost of using iron or carbon-based commercial filter media to remove H2S can act as a barrier to the uptake of on-farm biogas technology. To identify cost-effective, alternative options, this study tested and compared H2S removal by the commercial iron-oxide H2S scavenger (cg5) with the alternative solid media: granulated steel furnace slag (GSFS), red soil, compost, composted beef feedlot manure, granular activated carbon (GAC) and biochar. Experiments measured single-pass H2S removal from a pre-humidified standard gas (2000 ppm H2S in nitrogen) onto solid media contained in a cylindrical plastic column (DN 25 mm, depth 110–147 mm). The commercial medium (cg5) performed considerably better than the other media, achieving sulphur removal of 143 g S/kg medium at breakthrough (>10 ppm outlet H2S). A red soil was the most promising alternative medium (2–12 g S/kg medium at breakthrough). The crystalline structure of the iron-oxide minerals appeared to strongly influence the H2S removal capacity of the red soils, and pressure drop was generally high. Bulking with ground sugarcane mulch (SCM) was effective at reducing pressure drop. Interestingly, H2S removal with red soil improved when the soil was regenerated by exposure to air, followed by reuse in the column. Overall, red soil may be a suitable low-cost option, especially for polishing biogas after initial biological H2S removal

The need for year-specific correction factors (k values) when converting counts of individual common guillemots Uria aalge to breeding pairs

Long-term studies at two Scottish colonies show that the k value used to convert counts of individual Common Guillemots Uria aalge to pairs has changed substantially in the last 15 years due to decreases in survival and colony attendance. Any future wide-scale census of this species needs to collect concurrent k values if counts of individual birds are to be used to determine changes in breeding populations since the previous survey

a new Pc-C boundary section

The widespread, terminal Ediacaran Dengying Formation (~ 551–~ 542 Ma) of South China hosts one of the most prominent negative carbonate carbon isotope excursions in Earth's history and thus bears on the correlation of the Precambrian–Cambrian boundary worldwide. The dominantly carbonate strata of the Dengying Formation are largely studied for their unique preservation of its terminal Ediacaran fauna but their geochemical context is poorly known. This study presents the first high-resolution stable isotope record (δ13C, δ18O) of calcareous siliciclastic shallow-water deposits of the Gaojiashan section (Shaanxi Province). The section includes (in ascending order) the Algal Dolomite Member, the Gaojiashan Member and the Beiwan Member of the Dengying Formation. Our data record a major δ13Ccarb negative excursion to −6 ‰ in the uppermost Gaojiashan Member which is comparable in shape and magnitude to the global Precambrian–Cambrian boundary negative δ13C excursion. Our data set is consistent with a "shallow-water anoxia" scenario which is thought to contribute to the "Cambrian explosion". The stratigraphic occurrence of Cloudina and a large negative δ13C excursion suggest that the Precambrian–Cambrian boundary is located near the top of the Gaojiashan Member and, consequently, that overlying carbonates and dolomites of the Beiwan Member are of earliest Cambrian age. Thus the Gaojiashan section may represent a new shallow-water section spanning the Precambrian–Cambrian boundary. Although bio- and chemostratigraphic data support this novel interpretation, we cannot exclude the possibility that the key excursions may represent a local perturbation indicating a restricted-basin environment

Looking back to look forward : a systematic review of and research agenda for dynamic managerial capabilities

Abstract Given the complexities of today’s hypercompetitive economy and challenges imposed by recent crises, managerial capabilities have become critical for realizing strategic change. Dynamic managerial capability (DMC) theory offers a useful theoretical lens for analyzing how managers make strategic decisions to build and sustain competitive advantages in dynamic environments. Despite receiving less attention than the broader field of dynamic capabilities, the existing body of research has reached a point where a comprehensive synthesis of the current state of knowledge is warranted. Past reviews of DMCs are either outdated or do not comprehensively examine this multifaceted construct, making a review of research highly necessary and timely. This review systematically synthesizes 54 empirical studies on DMCs. It contributes to the literature by systematically synthesizing DMC research and summarizing these findings into a multi-level framework. This review demonstrates that research on DMCs has significantly progressed over the years, for example, through conceptual expansions, new levels of analysis, or methodological advancements. The developed framework provides an overview of the nomological network surrounding DMCs. A systematic historical analysis of research limitations and recommendations offers a rich research agenda for DMCs. These findings guide scholars and managers by overviewing the foundations of DMCs, demonstrating why strong DMCs are critical for achieving sustainable competitive advantage, and how this theory applies to management practice. Altogether, this review presents an up-to-date review of DMC literature by systematically synthesizing its developments— looking back —and pointing to central research opportunities— looking forward .M10;M1