This blog is the second of a series of blogs on waste management and the intersection of fecal and solid waste – both the challenges and opportunities. Based on learning experiences worldwide, solid waste management (SWM) and fecal sludge management (FSM) are closely linked. This blog series aims to demonstrate the opportunities for integrating FSM and SWM to improve how our world operates and creating financial value from these value chains. The blogs are a collaboration by Kim Worsham (FLUSH), Cuthbert A. Onikute (DalO Systems formerly Déchets a l’Or), Priska Prasetya, Sophie van den Berg and Verele de Vreede (WASTE) and Eline Bakker (Consultant).
The term waste is given when something no longer has a purpose. Sure, waste can be burned for ‘co-generation’ of heat or electricity, and this can be claimed to be a ‘recovery of resources’ but really this is a last resort. All resources, including rare earth elements, are lost during incineration – and landfilling much the same (although there is talk of mining landfills for resources). Reuse and recycling of resources requires separation of waste, perhaps better termed as ‘materials’ when there is value potential. When materials are separated where they are generated: at the source, there is usually the least contamination and the biggest opportunity for generating value. However, source separation is really hard – it is the achilles’ heel – when done right, it opens doors and business opportunity; when messed up, it complicates reuse and recycling systems and can cause the collapse and failure of waste management systems – in particular those waste management systems which rely on rebates/kick-backs from the sale of recyclables.
This blog post highlights that, to have an optimized integrated system with SWM and FSM, the wet and dry waste need to be segregated or even further separated (materials from each other).
Before we dig in, it is relevant to state that in this blog post, solid waste refers to municipal solid waste – it being the type of waste consisting of everyday items that are discarded by the public and importantly for the simplicity of this discussion devoid of industrial wastes, medical waste, hazardous waste, or sewage sludge.
There are two types of waste separation that this blog post discusses – (1) solid waste from fecal sludge and (2) solid waste types from each other. Both are important for integrating SWM and FSM and ensuring successful business models.
Firstly, any effort to collect high-quality fecal sludge from latrine pits must be void of solid waste pieces. As discussed in the first blog, the presence of solid waste significantly affects the efficiency and effectiveness of collecting and treating fecal sludge. Similarly, no waste management provider wants to deal with fecal-contaminated solid waste, whether that’s solid waste content removed from pit latrines or flying toilets. Flying toilets is the term for when people collect fecal matter in plastic (shopping) bags as a way to dispose of fecal waste when functioning toilets are few.
The other separation of waste is within solid waste – recyclables (like metals, glass, plastic, and paper), organic waste (like food scraps), and residual waste (like mixed plastic, diapers, etc.) should be separated to increase the value-add of recycled products that can be made from it. The composition of solid waste varies greatly by municipality, and changes with time (and quickly, since the introduction of plastic). There is no one-size-fits-all separation system because the system also depends on the market potential of recyclables (locally, regionally and globally).
The best results for quality organic municipal solid waste is separation at the source and involves preventing contamination of materials including plastic, glass, metals, paper, and general waste, etc. The first level of separation is ‘waste segregation,’ which means dividing waste into dry (non-organic) and wet (organic) streams. While waste managers can create additional income from selling recyclables, this blog makes the case that the one thing of value to do right, is to segregate the organics from non-organics. A clean organic stream creates opportunity for composting, co-composting, biogas digestion, briquettes and so much more. The art is in understanding society’s trigger point for behavior change.
Unsegregated solid waste impacts many different aspects of a waste business – for both solid waste and fecal sludge. Impacts include:
Missing the opportunity of segregation or even further separation can waste valuable resources. Organic waste that is not segregated from non-organic waste ends up – at best – on a controlled dumpsite or is incinerated. At a dumpsite it often degrades anaerobically (which means, without oxygen) and can contribute to greenhouse gas emissions. Incineration isn’t an energy efficient solution either, given the wet nature of organic waste, it takes a lot of energy to burn, in addition to losing valuable nutrients. Segregation is the first step to diverting valuable resources from landfills and other final disposal mechanisms.
Fecal sludge reuse initiatives require high quality organic solid waste so that the waste-to-value end-products (e.g., co-compost, briquettes) have some market value. Separating solid and fecal waste at the beginning also reduces the contamination of potential recyclables – increasing their marketing possibility and value.
Segregation of solid waste at the source significantly improves localised solutions and how waste is efficiently collected, and maximises how well we can create recovery options for solid waste (both organic and non-organic) and, consequently, fecal sludge. (Ricci-Jungensen and Ramola, Municipal organic solid waste, 2020).
For co-treatment processes, fecal sludge is often just a fraction of the total organics. For example, in co-composting systems, it is usually 3:1 for municipal organic waste to dried fecal sludge. This presents an interesting value proportion: (1) fecal waste can be sold as an add-on to organic waste treatment processes and (2) solid waste can be presented as a solution for more efficient and nutrient rich treatment of fecal waste. The cleaner the incoming material, the more efficient the operation, and the better the quality of the final product.
In the Nilgiris (India), waste management sites process both fecal sludge and solid waste to make co-compost. The co-composting plants have been in operation for four years. On site, there are constructed wetlands and solid waste separation piles. The plant employs approximately 11 people, whose primary focus is separating the non-organics from the organics, which is the most time consuming and challenging step of the co-composting process. As such, the programs’ efforts have focused on rolling out source segregation awareness campaigns, with better results and quality organic food waste from markets, carrot processing factories, schools, restaurants and hotels (SWFF – WASTE Performance Evaluation Report, 2019).
A side note – co-compost is compost enriched with nutrients from faecal waste – specifically nitrogen and phosphorus – which are important for plant and root growth. In other words, co-compost is a really good fertilizer and soil conditioner. At the same time, co-compost uses nutrients that are often discarded and otherwise lost to the environment, where they can contribute to algae blooms.
Solid waste segregation (wet from dry) should be mandatory; to make this happen, it needs participation from both the public, private and the government. How do we ensure that plastic and other solid waste types are not increasingly present in pit latrines and septic tanks? How do we safeguard the quality of fecal sludge and organic solid waste from the presence of non-organics (incl. plastic) to optimize the quality and sales price of waste-based products (e.g., briquette, co-compost, biogas)? The next blog post will cover circular economy business models that can establish a well-integrated FSM and SWM that improves FSM and SWM chains’ overall operational efficiency and financial sustainability.
Read more about source separation of household waste in Udaipur, India on WASTE’s website.
This particular series of blogs on integration of SWM and sanitation can be found here:
Blog 1: We Have a (Waste) Problem
Blog 4: The Business Model in Practice