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Global trends such as climate change and the scarcity of sustainable raw materials require adaptive, more flexible and resource-saving wastewater infrastructures for rural areas. Since 2018, in the community Reinighof, an isolated site in the countryside of Rhineland Palatinate (Germany), an autarkic, decentralized wastewater treatment and phosphorus recovery concept has been developed, implemented and tested. While feces are composted, an easy-to-operate system for producing struvite as a mineral fertilizer was developed and installed to recover phosphorus from urine. The nitrogen-containing supernatant of this process stage is treated in a special soil filter and afterwards discharged to a constructed wetland for grey water treatment, followed by an evaporation pond. To recover more than 90% of the phosphorus contained in the urine, the influence of the magnesium source, the dosing strategy, the molar ratio of Mg:P and the reaction and sedimentation time were investigated. The results show that, with a long reaction time of 1.5 h and a molar ratio of Mg:P above 1.3, constraints concerning magnesium source can be overcome and a stable process can be achieved even under varying boundary conditions. Within the special soil filter, the high ammonium nitrogen concentrations of over 3000 mg/L in the supernatant of the struvite reactor were considerably reduced. In the effluent of the following constructed wetland for grey water treatment, the ammonium-nitrogen concentrations were below 1 mg/L. This resource efficient decentralized wastewater treatment is self-sufficient, produces valuable fertilizer and does not need a centralized wastewater system as back up. It has high potential to be transferred to other rural communities.
Jingsi Xiao; Ulrike Alewell; Ingo Bruch; Heidrun Steinmetz. Development of a Self-Sustaining Wastewater Treatment with Phosphorus Recovery for Small Rural Settlements. Sustainability 2021, 13, 1363 .
AMA StyleJingsi Xiao, Ulrike Alewell, Ingo Bruch, Heidrun Steinmetz. Development of a Self-Sustaining Wastewater Treatment with Phosphorus Recovery for Small Rural Settlements. Sustainability. 2021; 13 (3):1363.
Chicago/Turabian StyleJingsi Xiao; Ulrike Alewell; Ingo Bruch; Heidrun Steinmetz. 2021. "Development of a Self-Sustaining Wastewater Treatment with Phosphorus Recovery for Small Rural Settlements." Sustainability 13, no. 3: 1363.
Phosphorus (P) is a key nutrient for agriculture and global food security, but the remaining phosphate rock reserves are finite and have increasing toxic impurities. Thus, phosphorus recovery from secondary waste sources, such as sewage sludge, became a strategic goal for the European Union to reduce its import dependency and stimulate circular economy. Previous studies focused on phosphorus recovery predominantly from primary, activated and anaerobically digested sludge but not from post-precipitated (tertiary) chemical sludge. In this research, leaching tests were performed with aluminum and iron containing tertiary sludge from two different wastewater treatment plants. The feasibility to re-dissolve the phosphorus bound into the sludges was investigated systematically by applying acidic or alkaline treatment. The shift in pH causes the dissolution of phosphorus which makes it readily available for further recovery as a high-value fertilizer product. For the aluminum containing sludge, the phosphorus re-dissolution efficiency after acidic leaching was ∼95% at pH 2.0. For the iron containing sludge, ∼80% efficiency was achieved only after significant acidification to pH 1.5. Alkaline leaching at pH 13 showed considerably lower potential with ∼70% phosphorus re-dissolution for the aluminum containing and ∼40% for the iron containing tertiary sludge. Additionally, the co-dissolution of the associated aluminum and iron metals was also analyzed and all experimental results were compared against data obtained from the leaching of anaerobically digested sewage sludge and synthetically precipitated sludge. In conclusion, the optimal pH for phosphorus dissolution depended strongly on the type of metal-phosphate compounds in the sludge.
Marlena Cristina Monea; Dirk Karsten Löhr; Carsten Meyer; Volker Preyl; Jingsi Xiao; Heidrun Steinmetz; Harald Schönberger; Asya Drenkova-Tuhtan. Comparing the leaching behavior of phosphorus, aluminum and iron from post-precipitated tertiary sludge and anaerobically digested sewage sludge aiming at phosphorus recovery. Journal of Cleaner Production 2019, 247, 119129 .
AMA StyleMarlena Cristina Monea, Dirk Karsten Löhr, Carsten Meyer, Volker Preyl, Jingsi Xiao, Heidrun Steinmetz, Harald Schönberger, Asya Drenkova-Tuhtan. Comparing the leaching behavior of phosphorus, aluminum and iron from post-precipitated tertiary sludge and anaerobically digested sewage sludge aiming at phosphorus recovery. Journal of Cleaner Production. 2019; 247 ():119129.
Chicago/Turabian StyleMarlena Cristina Monea; Dirk Karsten Löhr; Carsten Meyer; Volker Preyl; Jingsi Xiao; Heidrun Steinmetz; Harald Schönberger; Asya Drenkova-Tuhtan. 2019. "Comparing the leaching behavior of phosphorus, aluminum and iron from post-precipitated tertiary sludge and anaerobically digested sewage sludge aiming at phosphorus recovery." Journal of Cleaner Production 247, no. : 119129.