Cattle manure usually contains a proportion of carbohydrates in the form of organic residues from incompletely digested feed and farm husbandry practices. These are not usually available for biogas production due to the long fermentation time. This paper investigates the optimal application of alkali, NaOH and KOH and mechanical pre-treatments to improve the degradation of the lignocellulosic content and the potential biogas yields from a local farm in Bavaria, Germany. Parameters such as temperature, pH, soluble chemical oxygen demand, organic acids, dry matter and volatile solids were analysed for this purpose. Alkali pre-treatments in 0.2, 0.1 and 0.05 M NaOH concentrations were tested in single mode and combined with shredding in batch experiments. The maximum increment of the soluble chemical oxygen demand during the pre-treatments took place during the first 50 h of experimentation, and it showed an improvement of 10,060.0 ± 8% mg/L s COD after the application of 0.2 M NaOH compared to the untreated substrate, which had an initial value of 2145.0 ± 8% mg/L s COD. Pre-treatments with 0.1 and 0.05 M NaOH concentrations showed similar s COD increments, with an additional 6860.0 ± 8% mg/L s COD and 8505.0 ± 8% mg/L s COD, respectively. The pH values varied strongly after the addition of the pre-treatment chemicals, with a continuous pH of 12 by 0.2 M NaOH during the 7 days of pre-treatment. Batch biogas experiments were done by applying 0.05 M NaOH and 0.05 M KOH pre-treatments in single mode and combined with shredding. The chemically pre-treated substrates showed a faster biogas production with an advantage of 18 days in comparison to the untreated cattle manure by a biogas yield of 350.0 NL/kg VS. All experiments were done under mesophilic conditions.
Die Planung von Abwasserreinigungsanlagen stellt eine interdisziplinäre Leistung dar. Eine Beeinflussung der Projektkosten ist insbesondere zu Beginn des Projekts möglich. Gleichzeitig bestehen jedoch diverse Unsicherheiten, welche erst in Rahmen der Detailplanung im Projektverlauf beseitigt werden. In diesem Artikel wird am Beispiel einer Klärschlammvermeidungstechnologie eine Methode, wie durch die dynamische Kläranlagensimulation der Planungsprozess ab der Grundlagenermittlung unterstützt wird, demonstriert. Der Mehrwert liegt in der detaillierten und transparenten Darstellung der verfahrenstechnischen Zusammenhänge in der Abwasser- und Schlammbehandlung. Die Vorteile dieser Vorgehensweise werden an einem konkreten Beispiel dargestellt.
To assess the environmental impact of wastewater treatment, life cycle assessment (LCA) is a frequently applied instrument. However, these studies often require large amounts of data. The complexity and heterogeneity of these data result in the need for a systematic data management approach. Especially the generation of the life cycle inventory (LCI) holds the potential to be facilitated by automation. A case study in the wastewater sector was used to demonstrate the implementation of data management. A database structure was developed to store the raw data of the wastewater plants (WWTPs) and make it accessible through code. The code interacted with the database, implemented calculations, and automatically created the inventory based on the processed data. The database provides a consistent structure for the raw data and can also be used for backup purposes. Because it is machine-readable it can be accessed through the code that enables the automated generation of the LCI. As a proof of concept, a sequence of the code is provided with a user interface and can be tested online. We found that for most use cases, basic programming tools were sufficient for systematic data management, and, therefore, the approach is considered accessible for LCA practitioners.
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