Nitrogen is an essential element for life but its excessive release into the environment in the form of reactive nitrogen causes severe damage, including acidification and eutrophication. One of the main sources of nitrogen pollution is the use of fertilizers in agricultural soils. Feammox is a recently described pathway that couples ammonium (NH4+) oxidation with iron (Fe) reduction. In this study, the enrichment and bioaugmentation of anaerobic sludge under conditions that promote Feammox activity were investigated. The first enrichment stage (E1) achieved 28% of ammonium removal after 28 days of incubation, with a production of 30 mg/L of Fe2+. E1 was then used as inoculum for two enrichments at 35 degrees C with different carbon sources: sodium acetate (E2) and sodium bicarbonate (E3). Neither E2 nor E3 showed significant NH4+ removal, but E2 was highly effective in iron reduction, reaching Fe2+ concentrations of 110 mg/L. Additionally, an increase in nitrate (NO3-) concentration was observed, which may indicate the occurrence of this pathway in the Feammox process. The Monod kinetic model, analyzed using AQUASIM software, showed a good fit to the experimental data for NH4+, NO3-, and Fe2+. Sequencing analysis revealed the presence of phyla associated with Feammox activity. Although there was only a slight difference in NH4+ removal between the bioaugmented and non-augmented control sludge, the bioaugmented sludge was statistically superior in nitrate production and iron reduction. This study provides valuable insights into the enrichment and bioaugmentation of the Feammox process potential large-scale wastewater treatment applications.

Agriculture occupies more than a third of the world's land with many, large-scale impacts on the environment and human health. This article investigates the failure of policy to manage these impacts, asks whether private law can fill the gap, and what this means for policymakers. The investigation takes the form of a case study of synthetic nitrogen fertilizer (SNF) in English policy and law. The SNF industry has been chosen because, by its own account, it underpins the modern food system, which is recognized as needing urgent transformation. The article first assesses the damage caused by SNF to health and the environment and the potential legal remedies. It then assesses industry claims that SNF (a) provides food security, (b) is beneficial to soil and water, and (c) reduces greenhouse gas emissions. If misleading, these representations could amount to unlawful 'greenwashing'. While private law can never replace good policy and regulation, the article concludes that there is evidence to enable private law to supplement policy, and that this role is made possible as well as necessary by the absence of effective regulation and enforcement. Private litigation could catalyze policymakers to implement the robust regulatory regime that agriculture demands. As the law must focus on scientific evidence and causation, it can also help elucidate and publicize the science on which policy is based. Finally, because of the strict constraints within which private litigation must operate, it can direct policymakers towards strategic interventions (or tipping points) that could catalyze systemic change.