What are the disposal costs of sludge in India?
To maintain proper sanitation, there is a movement to establish sewage treatment plants (STPs) across India. As the demand for treatment technologies grows, there is a greater need to develop a costing benchmark across systems for Sewage Sludge. The benchmarking will enable governments to make educated decisions, resulting in a speedier roll-out of STPs.
Is sludge disposal consuming an inordinate amount of your operational budget?
According to statistics, solids management accounts for around 40% of a WWTF's overall yearly operational cost. That research also expected an increase in solids production in the future due to the increased requirement to minimize sewage's nitrogen and phosphorus impact to surface water basins. This is especially true for phosphorus (P).
Why do phosphorus limitations cause an increase in sludge?
Although nitrogen, which may be successfully removed biologically by nitrification and denitrification, relatively low phosphorus levels are normally achieved through chemical precipitation.
Traditionally, iron- or aluminium-based coagulants have been used. These coagulants significantly enhance sludge formation, producing 12 to 16 mg/L of sludge for every mg of “P” eliminated. They work on an adsorption mechanism, often needing a 2.5-to-1 molar ratio of iron or aluminium to phosphorus and a 4-to-1 molar ratio of phosphorus to iron or aluminium. They also produce a fluffy floc with a high concentration of bound water that is difficult to separate using settling and dewatering methods. The phosphorous, which acts as a solids-dispersing agent, suspends these solids, making them more difficult to settle. As a result, the sludge retains a high-water content and is expensive to dispose of.
The volume of sludge formed in a WWTP is only around 1% of the volume of influent wastewater to be treated (dewatered sludge is 0.5). Waste sludge, which comprises inert materials and surplus biomass, must be retrieved to prevent it from accumulating inside the system in order for WWTPs to operate smoothly and efficiently.
Sludge Handling Units: The Need for Sludge Reduction
A high number of non-biodegradable (inert) particles in particulate form inbound with the influent raw wastewater, contribute considerably to sludge production during biological wastewater treatment, in addition to cell biomass. Inert organic solids can be detected in sludge as a result of their presence in influent wastewater, endogenous residue formed during microbial decomposition, or protozoan activity, which may not completely dissolve the bacterial cell walls, leaving inert material behind.
As a result, comprehending and estimating the possible efficacy of a sludge reduction method necessitates a full grasp of sludge composition. A substantial percentage of refractory particle organic material must be transformed into a biodegradable fraction when a very high sludge reduction is sought.
The pricing methods
In India, an assessment of the implemented and to-be-implemented STPs is being carried out. The FSTPs are chosen largely on the basis of diverse technologies, and the cost analysis of these plants includes an assessment of capital and operating expenses.
The costing approach is a two-stage process designed to meet the objectives:
a. Secondary research methods, which include secondary information collection, site visits, interviews, and data analysis;
b. Primary and qualitative research, is being conducted to explore STP technologies, understand cost variances, and life cycle costing in order to identify reference costing.It also includes primary information collection, site visits, interviews, and data analysis.