phd project

Valorizing animal manure: facilitating phosphorus and coinciding resource recovery through biological treatment

Animal manure is the largest secondary source of phosphorus and contains significant amounts of nitrogen and potassium. The proper reuse of these nutrients is essential for increasing sustainability in agriculture. It will also play an important role in the energy transition, producing biogas and biomethane to achieve a reduction in fossil fuel consumption and CO2 emissions. The carbon returning to soil via land application can contribute to soil structure and strengthen soil health. A sustainable treatment of animal manure that can unlock the valorization of various resources will be of high societal relevance in the Netherlands and in the rest of the world.

At Wetsus, we developed resource recovery technologies that recover methane and phosphorus simultaneously during anaerobic digestion. These processes originated from source-separated wastewater treatment but recently were adapted to animal manure treatment. However, the mechanisms during animal manure treatment differ from those of wastewater treatment.

Research challenges

The complexity in the composition of animal manure made the recovery processes more challenging than from wastewater. In previous research, phosphorus recovery could be achieved from manure, but the process required more steering through chemical addition than desired. We identified competition between cations, kinetics of precipitation and abundance of inorganic carbon, among others, as obstacles and hypothesized how they affect the recovery mechanism.

In the upcoming research, we hope to adapt biological treatment steps to overcome these obstacles by creating conditions that stimulate beneficial biological processes. The challenge is to stimulate the correct processes that induce phosphorus precipitation while enhancing the recovery of biogas and other resources. The desired synergy for coinciding recovery requires an innovative approach to the entire process. Application of new biological processes, new reactor design, and redefining process conditions for manure treatment are all innovation opportunities in this project.

Your assignment

You will combine your biological treatment, crystallization, and reactor design knowledge to create a sustainable recovery process for nutrients and energy from animal manure. You will investigate a treatment process by running bioreactors on animal manure and upgrade their resource recovery potential by adopting new processes and optimizing them in the reactors. The process is based on fermentation and digestion processes and can be adapted or extended with other processes. You will characterize the treatment processes and recovery products with a variety of analyses to create mass balances over the systems for better understanding. Your understanding of the mechanisms behind the formation of recovery products will further improve the recovery process.

You will work with lab-scale reactors (up to 50L) and possibly get the chance to work with upscaled versions of the system. You will collaborate with stakeholders interested in the development of the technology.

Your profile

You hold an MSc degree in chemical or environmental engineering, biotechnology, or similar studies, or you have a background in natural sciences but a strong affinity for engineering. Previous experiences with resource recovery processes are a plus.

Keywords: Anaerobic digestion, Biocrystallization, Process design, Biotechnology, Agriculture

Supervisory team: Prof. dr. ir. Cees Buisman (Wageningen University), Dr. Renata van der Weijden (Wageningen University), Dr. ir. Chris Schott (Wetsus)

Project partners: Soil

Only applications that are complete, in English, and submitted via the application webpage before the deadline will be considered eligible.

Guidelines for applicants:

20-11-2017 Leeuwarden Wetsus Interieur Wetsus. Proefhal en laboratorium. ©Foto: Hoge Noorden/Jaap Schaaf