Reuse of Sludge as Organic Soil Amendment: Insights into the Current Situation and Potential Challenges

Sludge generation as an organic by-product of wastewater treatment has seen a consistent increase worldwide due to population growth and industrial activities. This poses a chronic challenge regarding management options and environmental concerns. The agricultural valorization of unconventional organic materials has become inevitable, especially in semi-arid and arid countries that suffer from depleted soils and shortages in farm manure supply. High-income countries have also been interested in this recycling practice to mitigate landfilling or incineration issues. Sewage and some industrial sludges contain a complex mixture of beneficial and harmful substances, which varies with the origin of effluents. Therefore, sludge land application should be well managed in order to achieve sustainable agro-environmental goals. This review paper focuses on different aspects related to sludge reuse in agriculture, starting by investigating the diversity of sludge types and composition. In addition to the preponderant urban sewage sludge, the less-studied industrial sludges, such as those generated from pulp and paper mills or gas-to-liquid industries, are hereby addressed as well. Then, post-land application effects are discussed in relation to sludge quality, dose, and reuse conditions. The present paper also examines the disparities between guidelines that determine sludge conformity for land application in various countries or regions. Accordingly, special attention is given to increasing risks related to emerging pollutants in sludge such as pharmaceuticals, which have been overused since the outbreak of COVID-19 pandemic. This exhaustive investigation will assist the establishment of sustainable strategies for the safe agricultural reuse of biosolids.

Poor housing and dark satanic mills

Articles in The BMJ this week featuring mills and housing may seem like a throwback, but the problems they raise, from science to social welfare, are very contemporary. The impact of the cost of living crisis is clear for health professionals to see, and, where once poor laws offered relief to people who were disadvantaged, recent law making and spending plans will not do enough for people feeling the “consequences of creaking public services in a nation getting poorer” (doi:10.1136/bmj.o2837).1

The impact of ownership structure and corporate governance on energy intensity: evidence from Indian business groups

Purpose>Energy efficiency is critical for global sustainability (International Energy Agency, 2019). The purpose of this paper is to examine how agency conflicts arising from pyramidal ownership structures impact the energy intensity (EI) of group-affiliated Indian firms. Group-affiliated firms face unique governance challenges. For instance, parent owners (promoters) may transfer profits from one group-affiliated firm to another firm in which they have greater ownership. The authors hypothesize that such governance issues will lead to underinvestment in energy-saving projects among group firms in which promoters have a low ownership stake, resulting in their greater EI.Design/methodology/approach>The authors measure EI as the ratio of total energy expense to total sales revenue (EI) and as the industry-adjusted version of this ratio. Group-affiliated Indian firms are divided into high- and low-stake firms based on the sample’s median promoter ownership.Findings>Results support the authors’ prediction: group firms in which promoters have low ownership are more energy intensive, consistent with these firms being exposed to greater governance challenges and agency conflicts that result in operating inefficiencies and/or underinvestment in energy-saving projects.Practical implications>Given energy efficiency will be key in addressing climate change, this study could raise awareness among activists, motivate regulators to consider agency problems among group-affiliated firms in emerging markets and may underscore the importance of environmental-related corporate disclosures.Originality/value>To the best of the authors’ knowledge, this study is the first to identify the significant impact that firm ownership structure and associated governance challenges have on corporate EI.