Welcome to RJ Dewaterintel Environment, Theme for Sludge Dewatering
Resource recovery is the talk of the wastewater industry, but maybe your facility is not so progressive just yet. While drawing energy from sludge or recycling it into fertilizer may be the wave of the future, what about the simpler goal of improving on good old-fashioned dewatering?
In actuality, dewatering has come quite a long way. Considerable innovation has been applied to what has long been a high-cost operation — the process of drying and hauling sludge — even if the technologies sound familiar (e.g., screw press, belt filter press, centrifuge). Additionally, research has been conducted to identify the critical factors that affect dewatering performance, allowing for process improvements irrespective of the dewatering technology applied. Manufacturers have leveraged the same research to offer equipment that dries sludge more thoroughly and efficiently, but there is no ‘one size fits all’ technology for end users; rather, it becomes a choice based upon waste stream, size of facility, budget, staff, and other factors.
To help guide decision-making, CH2M’s global technology leader and senior principal technologist, David Oerke, PE, presented an overview of technology options and best practices for sludge management at the 2016 Water Environment Federation Technical Exhibition and Conference (WEFTEC). Key takeaways from the presentation are summarized below.
Strengthening the construction of sludge treatment and disposal facilities
Sludge will dewater more or less effectively based on its characteristics, so an understanding of your sludge can produce better drying results and smarter procurement decisions. For example, Oerke notes that waste activated sludge (WAS) is difficult to dewater because much of the water gets attached to bacterial cells or taken up chemically in the cell structures. On the other hand, well-digested primary sludge is relatively easy to dewater.
When it comes to mechanical dewatering, higher concentrations of solids in the feed sludge yield increased amounts of cake solids, Oerke explains, since sludge that concentrates well in clarifiers or thickeners will concentrate similarly well in dewatering equipment.