Phosphorus mining from marine sediments adopting different carbon/nitrogen strategies driven by anaerobic reactors: The exploration of potential mechanism and microbial activities.

To investigate the possibility of phosphorus (P) recovery from marine sediment and explore the role of the carbon: nitrogen ratio in affecting the internal P release under anaerobic conditions, we experimented with the external addition of carbon (acetic acid and glucose) and ammonia nitrogen (NH4-N) to expose P release mechanisms. The 24-day anaerobic incubations were conducted with four different carbon: nitrogen dosing groups including no NH4-N addition and COD/N ratios of 100, 50, and 10. The P release showed that extra NH4-N loading significantly suppressed the decomposition of P (p < 0.05) from the marine sediment, the maximum P release was 4.07 mg/L and 7.14 mg/L in acetic acid- and glucose-fed systems, respectively, without extra NH4-N addition. Additionally, the results exhibited that the imbalance of carbon: nitrogen not only failed to induce the production of organic P mineralization enzyme (alkaline phosphatase) in the sediment but also suppressed its activity under anaerobic conditions. The highest enzyme activity was observed in the group without additional NH4-N dosage, with rates of 1046.4 mg/(kg∙h) in the acetic acid- and 967.8 mg/(kg∙h) in the glucose-fed system, respectively. Microbial data analysis indicated that a decrease in the abundance of P release-regulating bacteria, including polyphosphate-accumulating organisms (Rhodobacteraceae) and sulfate-reducing bacteria (Desulfosarcinaceae), was observed in the high NH4-N addition groups. The observed reduction in enzyme activity and suppression of microbial activity mentioned above could potentially account for the inhibited P decomposition in the presence of high NH4-N addition under anaerobic conditions. The produced P-enriched solution from the bioreactors may offer a promising source for future recovery endeavors.

Phosphorus mining from eutrophic marine environment towards a blue economy: The role of bio-based applications.

Global phosphorus reserves are under pressure of depletion in the near future due to increased consumption of primary phosphorus reservoirs and improper management of phosphorus. At the same time, a considerable portion of global marine water bodies has been suffering from eutrophication due to excessive nutrient loading. The marine environment can be considered as a valuable phosphorus source due to nutrient rich eutrophic seawater and sediment which could potentially serve as phosphorus mines in the near future. Hence, sustainable phosphorus recovery strategies should be adapted for marine systems to provide phosphorus for the growing market demand and simultaneously control eutrophication. In this review, possible sustainable strategies for phosphorus removal and recovery from marine environments are discussed in detail. Bio-based strategies relying on natural phosphorus uptake/release metabolism of living organisms are suggested as promising options that can provide both phosphorus removal and recovery from marine waters for achieving a sustainable marine ecosystem. Among them, the utilization of microorganisms seems promising to develop novel strategies. However, the research gap for the technical applicability of these strategies is still considerably big. Therefore, future research should focus on the technical development of the strategies through laboratory and/or field studies. Coupling phosphorus mining with other valorisation pathways (i.e., metal recovery, energy production) is also suggested to improve overall sustainability and economic viability. Environmental, economic and societal challenges should altogether be well addressed prior to real scale applications.

Adopting citizen science approach for water quality monitoring in Uzungöl, Turkey.

In the present study, adopting of citizen science approach for monitoring water quality of a lake (Uzungöl, Turkey) was investigated. The study consisted of selection of sampling points and water quality parameters, training of volunteers, sampling and analysis by volunteers, and development of a mobile application for data collection and storage. In the scope of the study, four measurement points around the lake were selected and elementary school students were trained both theoretically and practically to collect water quality data. During the project (June-December, 2018), volunteers collected water samples and measured temperature, pH, nitrate, and phosphate with the given test kits. The mobile application was developed using open source code and used to collect and store the volunteer data. According to the volunteer data, temperature values were between 8.5 and 15.5 °C, pH values were between 2 and 8.5, nitrate values were between 0.5 and 2.5 mg/L, and phosphate values were between 0.5 and 5 mg/L in the lake. Most of the pH and temperature results were compatible with field measurements done by research group during field visits. The motivation of the volunteers and mobile application development were the achievements of the project. Low number of the data and its reliability were the main limitations. Therefore, this study showed that citizen science has both capabilities and constraints for collection of water quality data, however; outstanding potential of citizen science is obvious.