Publications by authors named "Hans Oechsner"

Phosphorus (P) is critical for plant growth, but global reserves are exhausting within 250-300 years, therefore enhancing phosphate recycling is crucial for the future. Biogas digestate, rich with nutrients is a promising resource for nutrient recovery. Conventional solid-liquid separation shifts approximately 35 % of the total P in the digestate to the solid phase.

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Phosphorus(P) recycling from waste streams is crucial to mitigate the P depletion crisis. P forms and contents in organic waste are critical for determining the recycling method and efficiency. We constructed an approach to characterize P forms in seven organic waste by combining chemical sequential extraction, enzymatic hydrolysis, and nuclear magnetic resonance(NMR).

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In recent decades, the importance of managing the earth's dwindling phosphorus (P) has grown exponentially, as have efforts to develop a circular economy. Livestock manure represents a P-rich waste product, so recycling P from livestock manure has garnered the attention of scholars worldwide. Based on a global database from 1978 to 2021, this study presents the current status of recycling P from livestock manure and proposes strategies for efficient P utilization.

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Phosphorus (P) species characterize the effectiveness of the P fertilizer. In this study, the P species and distribution in different manures (pig manure, dairy manure and chicken manure) and their digestate were systematically investigated through combined characterization methods of Hedley fractionation (HOP, NaHCO-P, NaOH-P, HCl-P, and Residual), X-ray diffraction (XRD) and nuclear magnetic resonance (NMR) techniques. The results from Hedley fractionation showed that >80 % of P in the digestate was inorganic and the HCl-P content in manure increased significantly during anaerobic digestion (AD).

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The organic fraction of municipal solid waste (OFMSW) is a complex material with different ingredients characterized by varying properties depending on parameters such as season or geographical region of origin. Consequently, studies on OFMSW are hard to compare due to the changing characteristics of the samples. Therefore, this article presents data on the physico-chemical composition of standardized, recipe-based OFMSW components divided into the categories "Paper", "Green waste" and "Food waste", and further subcategories.

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Two-stage anaerobic digestion (TSAD) systems have been studied on a laboratory scale for about 50 years. However, they have not yet reached industrial scale despite their potential for future energy systems. This review provides an analysis of the TSAD technology, including the influence of process parameters on biomass conversion rates.

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Banana trees and fruits with three ripening stages, including green, ripe, and overripe, of two cultivars, namely Nam wa and Hom were separated into different morphological parts for biogas yield determination. Specific methane yields (SMY) were significant different among banana parts (p ≤ 0.05).

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In a two-stage CSTR system, the anaerobic digestion effluent from the second stage (methane reactor) can be used for pH-control in the acidification reactor. But using batch leach bed reactors, controlling the pH-value is key affecting factor due to dynamic process conditions. The aim of this work was to study, an automatized technical-scale leach bed reactor system for VFA-production with pH-dependent flushing.

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The world is facing huge phosphate (P) shortage and anaerobic digestion (AD) is a recognized technology to promote nutrient (N and P) recycling. The composition of P speciation in the digestate is essential for the fertilizing effect. However, how P speciation in the digestates interacts with the AD process conditions is unknown.

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Food waste (FW) from households represents a major fraction of municipal waste and it is often collected in separate biowaste bins. Until waste collection is carried out, storage conditions in the biowaste bin influence FW properties. To draw conclusions for an optimized waste utilization in anaerobic digestion (AD), the aim of this study was to evaluate the impact of storage duration (20 to 40 days) and temperature (5 °C and 20 °C) on inherent energy potentials of household FW during aerobic and anaerobic storage.

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In the municipal context and depending on the collection scheme, different waste streams are of relevance. This article contains year-round data on the chemical composition of organic fractions of municipal solid waste (OFMSW) of rural and urban origins. All samples were collected in the municipality of Tübingen, which is located in southern Germany.

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Knowledge on material properties is beneficial to fully exploit inherent utilization potentials of the organic fraction of municipal solid waste (OFMSW). The objective of this study was to analyze and compare the physico-chemical characteristics of separately collected OFMSW (biowaste bin) originating in southwestern Germany. Therefore, 22 rural and 20 urban OFMSW samples, each from the same location were analyzed in the course of one year.

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Anaerobic digestion (AD) is a matured technology for waste (water) remediation/stabilization and bioenergy generation in the form of biogas. AD technology has several inherent benefits ranging from generating renewable energy, remediating waste (water), and reducing greenhouse gas emission to improving health/hygiene and the overall socio-economic status of rural communities in developing nations. In recent years, there has been a paradigm shift in applications of AD technology beyond biogas.

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In the field of biological hydrogen methanation, ideal process parameters are underexplored for continuous two-stage systems with anaerobic filters. The present study aims at filling this gap for continuous in-situ reactors while applying different hydrogen injection rates. The results of the study demonstrate an almost complete acid degradation on the output side of the anaerobic filter fed by hydrolysate from maize silage and silage effluent.

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The biogas digestate from anaerobic digestion of cow manure and energy crops was treated by hydrothermal carbonization (HTC) at 210 °C for 0.5 to 5 h to understand the effect of HTC residence time on the combustion characteristics of hydrochar and the biogas production of process water. The increase in HTC residence time slightly reduced the higher heating values (16.

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This work studied the demand-oriented biogas production and the biogas storage in digestate by flexibly feeding a full-scale research biogas plant. The investigated continuous stirred tank reactor (CSTR) was equipped with a fast-moving submersible motor mixer and a slow-moving inclined shaft agitator. A model for the biogas storage in digestate was introduced and tested in full scale using temporally highly resolved volume flow measurements.

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The major share of phosphate in biogas digestate is inorganic. For optimized nutrient recovery, inorganic phosphate must be analyzed adequately. Therefore, the photometric spectra of extracts from Hedley fractionation were measured and analyzed for their peaks using the molybdenum blue method.

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Anaerobic co-digestion of organic fraction of municipal solid waste with solid content greater than 20% and chicken manure was investigated using leach-bed reactors in the framework of Middle East and North African countries. The objectives of the experiments were to determine the optimal ratio of organic fraction, chicken manure and solid inoculum, to compare temperature conditions and usage of liquid inoculum or water in percolation process. The highest specific methane yield (SMY) (236 L ∙ kg VS) was received in the reactors with 20/80 organic fraction/solid inoculum ratio under thermophilic conditions with liquid inoculum percolation.

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Phosphorus (P) loss from livestock and poultry industry causes serious threat to agro-ecological environments. Anaerobic digestion (AD), through recycling of P-containing resources and biogas production, prevails as a promising solution to the resource, energy, and environment trilemma. In this study, the dynamic transformation of P in batch AD processes fed with chicken, pig and dairy manures was investigated.

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This article contains data on the chemical composition and anaerobic digestion of different residue streams including OFMSW, digested sewage sludge, low-carbon (LC) ashes from incineration subdivided into LC coarse and LC fly ash as well as high-carbon (HC) ashes from gasification subdivided into HC reactor and HC fly ash. All materials were collected in accordance to standard procedures in southern Germany. The data presented in this article include (1) dry matter (2) organic dry matter (3) elemental analysis (4) trace elements and (5) cumulative biogas and CH yields.

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The purpose of this study is to test alternative additives for trace element (TE) supplementation and process stabilization during anaerobic digestion (AD) of the organic fraction of municipal solid waste (OFMSW) and sewage sludge. Process instabilities due to acidification are a typical problem in waste fermentation. Provision with minerals and TE is crucial for microorganisms in AD to work effectively, allowing higher organic loading rates within the digester without risking acid accumulation.

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This study examined the composition and anaerobic digestibility of the different plant parts of two high-yielding tropical energy crops, Energycane and Napier grass, collected across three locations and two seasons. Both biomass composition and biomethane yields varied significantly with crop types, plant parts and harvest seasons. In Energycane, specific methane yield (SMY) (Nm (kg VS)) was higher from stems (0.

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In this study, the anaerobic performance and stability of coffee husk and pulp with and without trace element (TE) supplement was investigated, using 20 L mesophilic continuous stirred tank reactors for 140 days of experiment (DOE). The TE was cocktail of trace metals composed of Fe, Ni, Zn, Co, Mn, Mo, Se W and B. The organic loading rate (OLR) was increased stepwise from 2.

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This study aimed to uncover microbial dynamics and transcriptional adaptations during mesophilic AD of maize silage and slurry. While one digester performed under optimal conditions, the investigations also evaluated the microbiome during a temperature drop mediated process failure accompanied by acidification and how it contributed to a process recovery. Composition and pathway activities were analyzed by whole genome shotgun (WGS) and metatranscriptome sequencing, respectively.

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