Exploiting the Nutrient Potential of Anaerobically Digested Sewage Sludge: A Review

Abstract

The world is currently witnessing a rapid increase in sewage sludge (SS) production, due to the increased demand for wastewater treatment. Therefore, SS management is crucial for the economic and environmental sustainability of wastewater treatment plants. The recovery of nutrients from SS has been identified as a fundamental step to enable the transition from a linear to a circular economy, turning SS into an economic and sustainable source of materials. SS is often treated via anaerobic digestion, to pursue energy recovery via biogas generation. Anaerobically digested sewage sludge (ADS) is a valuable source of organic matter and nutrients, and significant advances have been made in recent years in methods and technologies for nutrient recovery from ADS. The purpose of this study is to provide a comprehensive overview, describing the advantages and drawbacks of the available and emerging technologies for recovery of nitrogen (N), phosphorus (P), and potassium (K) from ADS. This work critically reviews the established and novel technologies, which are classified by their ability to recover a specific nutrient (ammonia stripping) or to allow the simultaneous recovery of multiple elements (struvite precipitation, ion exchange, membrane technologies, and thermal treatments). This study compares the described technologies in terms of nutrient recovery efficiency, capital, and operational costs, as well as their feasibility for full-scale application, revealing the current state of the art and future perspectives on this topic.

Methane Production from Confectionery Wastewater Treated in the Anaerobic Labyrinth-Flow Bioreactor

“…During anaerobic digestion, the removal of nitrogen and phosphorus from sewage is low and mainly related to the biomass cells growing [60]. Thus, generally, the biological degradation of the organic matter leads to an increase in the concentration of soluble nutrient species in digestate, in the form of ammonia nitrogen and orthophosphate [61]. The results of this work could be taken for optimizing the operational conditions of the full-scale plant and also as a starting basis for scaling up the process to the industrial scale.…”

Enhanced bioenergy and nutrients recovery from wastewater using hybrid anodes in microbial nutrient recovery system

“…The recovery percentage of NH 4 + ions rose steadily during 10 days of operation of all the hybrids MNRC systems, reaching maximum of ~ 73% for AC:Chi (1:1) based MNRC systems and ~ 70.2% for AC:Chi (2:1) and ~ 68% for AC:Chi (3:1) MNRC, respectively. The significant increase in NH 4 + ion recovery might potentially be a result of the bacteria decomposing organic materials into ammonia in the anodic chamber [ 31 ]. The electron generated during the oxidation of organic materials in the anode chamber was delivered to the cathode for power generation.…”

Start-up and performance of a downflow fluidised bed reactor for biological treatment of yellow wastewater and nutrient recovery

“…The theoretical composition of the precipitates obtained from this experiment were close to that of pure struvite, indicating that at least 84% was struvite by dry weight. However, the presence of other cations such as Ca 2þ , Na þ and K þ can interfere in the crystal formation of struvite; by replacing the NH 4 þ , K-struvite can be formed (Di Costanzo et al 2021).…”