Elodea nuttallii (PLANCH) St. John, an aquatic plant native to North America, shows invasive traits outside of its area of origin. In Europe, the plant has spread rapidly in water bodies. In Germany, the massive occurrence of E. nuttallii restricts recreational activities on lakes. Massive occurrences of E. nuttallii have been managed up to now by harvesting the plant and disposing of the biomass as organic waste, which results in high maintenance costs for lake administrators. Alternative uses to the disposal of the biomass were investigated. Analyzing the components and elemental composition of E. nuttallii samples from nine lakes in Germany, several potential uses were identified, such as the use of E. nuttallii biomass as a co-substrate with maize silage for biogas generation. Other potential applications, such as biochart production, soil amelioration, and energy recovery of feedstock chars in combustion plants, were identified from a hydrothermal carbonization process. The presence of β-sitosterol in E. nuttallii, which is used in the treatment of enlarged prostates, indicates a pharmaceutical use. Even though the elemental composition of E. nuttallii biomass contains the elements of a complete fertilizer, this particular use is not recommended given its slow decomposition in soil. The most feasible alternative identified was the use of E. nuttallii biomass as a co-substrate for biogas generation in combination with maize silage. The mixing of E. nuttallii with maize silage to facilitate storage and short distances between biogas plants and lakes with massive occurrence of E. nuttallii are important factors for its applicability.

In this work, investigations dealing with the determination of hydrocarbons in contaminated soil water are presented. The hydrocarbons under investigation range from low to high volatility compounds. A GC-FID method was developed that due to its efficiency, routine suitability, relative rapidity, and low cost is suitable for the analysis of complex chemical mixtures of highly volatile hydrocarbons (with boiling points between 69 and 1908C). The standard used was a gasoline mixture with boiling points ranging from 100 to 1908C. For this standard, no supplementary preparation is needed and it is suitable for the whole range of hydrocarbons under investigation. The determination of the hydrocarbon content of the samples was performed applying univariate and multivariate statistical analysis to the experimental data. In the characterization of a contamination with highly volatile hydrocarbons of soil water originating from different depth layers from the chemistry location Leuna (SachsenAnhalt, Germany), the advantages of a multivariate method are demonstrated in exemplary manner.

The effectiveness of different remediation procedures for decreasing the amount of TPH (total petroleum hydrocarbons) in contaminated groundwater was evaluated at the site of a former refinery. The investigations were carried out on samples taken from several gravel based HSSF (horizontal subsurface flow) constructed wetlands (CW) which differed in relation to their filter material additives (no additive, charcoal, and ferric oxides additives) and examined the potential effect of these additives on the overall treatment efficiency. Samples of the following gravel based HSSF CW were investigated. No filter additive (system A), 0.1% activated carbon (system B), 0.5% iron(III) hydroxide (system C), and the reference (system D). Systems A–C were planted with common reed (Phragmites australis), whereas system D remained unplanted. In addition, the influence of seasonal conditions on the reduction of these hydrocarbons and the correlation between the amounts of TPH and BTEX (benzene, toluene, ethylbenzene, and xylene isomers), on the one hand, and methyl tert‐butyl ether, on the other, was investigated. The study was carried out by using a modified GC‐FID approach and multivariate methods. The investigations carried out in the first year of operation demonstrated that the effectiveness of the petroleum hydrocarbon removal was highest and reached a level of 93 ± 3.5% when HSSF filters with activated carbon as a filter additive were used. This remediation method allowed the petroleum hydrocarbon content to be reduced independently of seasonal conditions. The correlation between the reduction of TPH and BTEX was found to be R = 0.8824. Using this correlation coefficient, the time‐consuming determination of the BTEX content was no longer necessary.