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Energieeffizientes Nährstoffsplitting von flüssigen Wirtschaftsdüngern mittels Membranfiltration
(2017)
Die definierte Selektivität der Membranfiltration kann dazu genutzt werden, einzelne spezifische Gülle-Separationsprobleme in übergeordneten Aufbereitungsklassen zusammenzufassen. Mit dem Ansatz einer gesteuerten Nährstofftrennung bzw. Teilzusammenführung von modifizierten Strömen, und der Zuordnung von spezifischen Aufgaben an die Mischprodukte, werden die Nachteile des Ausgangsrohstoffs reduziert und der Wertstoff Gülle rückstandsfrei nutzbar gemacht. Mit einem Anlagenmodell, bestehend aus einer Hydrotankpresse als Vorfiltration und einer Ultrafiltration als Kernkomponenten, ist es über empirisch ermittelte Betriebsparameter möglich, einen energetisch optimierten und kontinuierlichen Produktionsbetrieb durchzuführen. Als Produkte der dezentralen Aufbereitungsanlage werden ein emissionsreduzierender Flüssigdünger, eine als Brennstoff und als Gärsubstrat geeignete Feststoffphase, sowie das Retentat als aktivierendes Material zur Biogasertragssteigerung gewonnen. Das untersuchte Anlagenmodell ist auf den innerbetrieblichen Einsatz in Milchviehhaltungsbetrieben abgestimmt. Mit der Erarbeitung von stabilen und energetisch günstigen Anlagenbetriebspunkten wird das Anlagenverhalten hydraulisch steuerbar. Durch die Zuordnung von Anlagenzuständen zu differenziertem Spülverhalten, wird die direkte Einflussnahme der Temperatur auf den Permeat-Flux erkennbar. Der Einsatz eines Tauchkühlers, mit voreingestellten Grenztemperaturen, stabilisiert signifikant das Anlagenverhalten im Vergleich zu konventionellen Anlagenkonfigurationen. Die Anwendung einer Hydropresse gestattet höhere TDS-Belastungen im UF-Kreislauf, bietet aber kein Potenzial zur Steigerung der Nährstoffdurchsätze. Dies gilt auch für den Einsatz einer 300 kDa-Variante, im Vergleich zur priorisierten 150 kDa-UF-Membran. Mit der Hydropresse kann eine höhere Feststoffabscheidung wie mit Verstopfungs- bzw. Siebfiltrationen erreicht werden, die TDS-Belastungen sind im Retentat auf 5.000 - 7.000 ppm limitiert, oder müssen durch Verdünnung auf diese Werte eingegrenzt werden. Mit der zusätzlichen Anwendung einer Gasspülung in der Anströmung der UF-Module, können TDS-Belastungen über 10.000 ppm erstmals dauerhaft bewältigt werden. Über die so erweiterte Verfahrenstechnik sind Standzeiten von mehreren Wochen, ohne betrieblich bedingte Unterbrechungen, möglich. Die durch Fluoreszenzmikroskopie nachweisbare Anreicherung von Methanbildnern im Retentat, bestätigt eine mögliche Anwendung des Retentats als Biogassubstratergänzung. Der Biogasertrag wird durch Zusatz von Retentat zu den bisher verfügbaren Substraten generell erhöht. Eine Mischung aus Retentat und dem Feststoff aus der Hydropresse unterstützen die biochemische Stabilisierung in Fermentern. In Kombination mit Anteilen an Feststoff ist das Permeat bei der Bewertung von pflanzenbaulichen Erträgen, als konkurrenzfähig zu Rohgülle und Mineralstoffdünger einzustufen. Das auf landwirtschaftliche Flächen ausgebrachte Permeat ist geruchslos.
Groundwater is an important resource in Sub-Saharan Africa to supply water for domestic, industrial, mining and irrigation for agricultural purposes. In Ghana, groundwater supply program is mostly pragmatic to give people drinking water, however to ensure sustainability a long term groundwater management system is essential. One such approach is the use source protection (well protection) with the declaration and installation of protection zones. To achieve the goal of this research three hypothetical questions were asked which relates to the Availability and Vulnerability of groundwater, and the use of an analytical model to estimate source protection zones (SPZ). The regions of Adansi, Lawra, Sunyani and Sekyere West were chosen as study areas to test the hypothesis of this research with detailed investigation concentrating on Adansi area. The overall aim from the study areas was to estimate SPZ for Granite, Phyllite, Schist, Sandstone and weathered materials and give recommendations as to which activity should be permitted or otherwise within each of these zones. The available groundwater for a particular well or location was determined based on its hydraulic conductivity and specific capacity of a well. Regionalization of the available groundwater was achieved by comparing the results of the hydraulic conductivity and specific capacity with the regional structural map. To determine the vulnerability of the available groundwater, the radius of influence (ROI) for the different boreholes was determined using Sichard and Dupuits formula whilst for Source protection zones, Darcy and the volumetric equation was used. Results of hydraulic conductivity estimated from pumping test data for the five major rock types showed a trimodal distribution (E-5, E-6 and E-7 m/s). There was a general trend of decreasing hydraulic conductivity to decreasing transmissivity. Results of plots of specific capacity verses hydraulic conductivity shows that only rock types with hydraulic conductivity greater than E-5 m/s yields sustainable groundwater supply. Three aquifer types were encountered in the study areas which were pore aquifers in shallow or alluvial, regolith and fracture aquifers in bedrocks. High hydraulic conductivity from the different rock types corresponds to higher ROI. The results of hydraulic conductivity, specific capacity, ROI and SPZ are used as input parameters for the estimation of the suitability of a groundwater source. A ranking matrix was developed for easy interpretation of hydrogeological data by combining the results of the input parameters into a single score. Results from the ranking matrix were used to determine specific regulations for the various aquifers in the study areas. Within the fractured crystalline rocks with k ≥E-5m/s siting of wells should target fracture zones whilst pumping during abstraction phase can exceed 15m3/s/m. The intermediate source protection zone should be at least 150m. Conclusions from the study could be applied in other areas of Ghana and be implemented during the initial development, abstraction and groundwater policy phases of other groundwater projects.
This study analyses corporate environmental performance in the manufacturing and mining sectors of Ghana within a framework of environmental governance. The research is premised on the fact that industry contributes to pollution, raw material depletion and natural resources use. Hence industry is equally expected to play a role in pollution reduction and minimisation of raw materials and natural resources usage. The study makes use of both quantitative and qualitative research approaches drawing on both primary and secondary sources of data. Through SWOT analysis, an evaluation of the regulatory framework governing environmental governance was carried out and new opportunities for effective environmental management espoused. In addition, the policy instruments available for environmental governance were thoroughly analysed and discussed in this research. Further, through comparative analysis the environmental initiatives of industries in the manufacturing sector were investigated on the basis of size and industry type. The study developed a model based on 22 indicators in 3 thematic areas namely (1) legal and regulatory compliance, (2) pollution control and resource conservation initiatives and (3) environmental planning and policy initiatives to evaluate corporate environmental performance in manufacturing industries. To quantify corporate environmental performance, a Likert-scale 1-5 was applied to assess performance in the 3 thematic areas mentioned. These scores were aggregated, averaged and analysed using Microsoft Excel software. A “Corporate Environmental Performance Perception (CEPPI) index” was developed to evaluate how different industries performed on key corporate environmental governance dimensions. The results among other things showed that in terms of size, Small to Medium Enterprises (SMEs) lagged behind large enterprises in their environmental performance. In terms of industry type however, “metal works” showed relatively low performance on the “CEPPI” scale. The findings were discussed and strategies to help enterprises that lag behind to improve their environmental performances were given. In addition to the above, the study further investigated the Corporate Social and Environmental responsibility (CSR) initiatives of the mining industry. Corporate social and environmental responsibility has been used as proxy measure of environmental performance by the mining industry. Among other things, the findings showed that CSR as “preached” by the mining companies was to some extent inconsistent with CSR as “perceived” by the mining communities. The evidence thus seems to suggest a lot more has to be done by the mining companies as well as local communities where these mining firms operate to achieve high environmental performance. The implications of this research in terms of what has to be done to improve environmental responsiveness of the mining companies were given. A comprehensive strategy, focussing on both voluntary codes and ‘command and control’ regulations, as well as a strategy for institutionalising environmental management culture in Ghana’s manufacturing and mining industries were provided.