618 research outputs found
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,
Managing innovation in a globalized digital economy: An empirical inquiry into managerial-, governance-, and firm-level antecedents and contingencies
The impact of dynamic managerial capabilities on firm performance : A moderated mediation analysis of German DAX firms
Looking back to look forward : a systematic review of and research agenda for dynamic managerial capabilities
WHEAT DISEASE MANAGEMENT WITH FUNGICIDES: QOI-RESISTANT \u3ci\u3e PARASTAGONOSPORA NODORUM \u3c/i\u3e AND \u3ci\u3e ZYMOSEPTORIA TRITICI, \u3c/i\u3e APPLICATION TIMING FOR LEAF DISEASE MANAGEMENT, AND SPRAYER CONFIGURATIONS FOR FUSARIUM HEAD BLIGHT MANAGEMENT
Disease management in winter wheat can be improved by a properly implemented foliar fungicide program. The fungicide, application time, and application system should be selected based on the host, pathogens present, risk of fungicide resistance, and time of disease onset. These factors vary among environments and require region-specific research to determine appropriate practices. Trials were conducted to evaluate different aspects of fungicide applications for managing Fusarium head blight (FHB), caused by Fusarium graminearum, and the Septoria tritici leaf blotch complex, caused by Zymoseptoria tritici and Parastagonospora nodorum. A survey of P. nodorum isolates from Kentucky and Illinois and Z. tritici isolates from Kentucky showed that both pathogen populations included strains that were resistant to quinone outside inhibitor (QoI) fungicides. Trials were conducted to determine the optimal fungicide application time to manage the Septoria leaf blotch complex, and whether disease management programs benefited from adding a foliar fungicide. The effect that sprayer speed, nozzle type, and configuration had on coverage of wheat heads and FHB management was evaluated. Applying alternative fungicide chemistries to the QoI class at Feekes 9 along with an application at Feekes 10.51 made with an appropriate nozzle and application speed will provide a more effective fungicide program for winter wheat in Kentucky
An examination of Achenbach's empirical taxonomy and covariation between syndromes in different sex, age and clinic status groups
Antecedents to cognitive business model evaluation: a dynamic managerial capabilities perspective
Does board composition matter for innovation? A longitudinal study of the organizational slack–innovation relationship in Nasdaq-100 companies
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