This last blog in sludge management will attempt to sum up what the other three blogs have already said and add a little bit more, looking at sludge management from a holistic point of view.
So what is sludge all about, it used to be how we dispose of the waste products from the wastewater process, previously to sea and then to landfill. For many years now it has been about the product and what we can do with that product and like all other production based industries this needs process control and automation and tracking of the process. Sludge within the wastewater industry is doing this and has adopted HACCP in order to manage the quality of the product. Is the industry fully there yet, I think the answer is a most definite no but it is getting there. But where exactly there?
Well to answer that question we need to analyse what the product is and what we want to do with it. In sludge there are three products, the biosolids that has always been the end product of sludge management, energy that we can recover from the sludge and finally nutrients that can be recovered from the sludge liquors.
So what pieces of information do we actually need?
Sludge volume management into the sludge treatment process – This was covered in the first blog and basically allows the management of the different types of sludges but also what types of sludges are in the business and where. This allows that the right amount of sludge gets to the right place at the right time in the most efficient way. Allowing not only for tracking what sludge is where and of course sludge tanker management as well
The next step is product management within the sludge treatment facility. Like any factory setting this is all about controlling the throughput through the process and ensuring what you are producing is of a good standard. This is where the wastewater industry has adopted the HACCP process to ensure the quality, something that has worked very well. On top of this though is ways of optimising this process and ensuring that the maximum amount of product is yielded from the process. Quality management tends to be well done within the industry, quantification of how much product, less so. But lets examine the principles of HACCP within the sludge treatment facility and what its scope is?
Arguably within the sludge treatment facility the HACCP principle looks at getting the sludge product to the right quality for distribution out to the “customer.” However the biosolids are not the only product, energy and nutrients are the others. In conducting the HACCP analysis all of these products have to be accounted for. What the HACCP principle didn’t take into account was volumetric throughput but in terms of the wastewater industry this should already be accounted for as the process can only take a certain amount of throughput before the quality suffers and the system starts to breakdown. An example of this is solids loading on a digester, not enough or too much solids will cause the gas quality to falter and the critical control point to be breached. If the HACCP principles are stuck to then the treatment facility should be a controllable to get the best product from the resources that are avaiable
The final step of course within sludge management is where all of the biosolids and nutrients go. This is basically a sales management system and tracks where all of the products go. This is something that the water industry is not necessarily familiar with but can learn from other industries such as the retail industry.
The future for sludge treatment has been realised for many years and the overall management system of processing sludge through the sludge collection, treatment and distribution process is well understood but poorly monitored in places meaning that the right data and information is not available at the right place and at the right time. This is the final step that the industry needs to take in order to manage its sludge treatment processes.