I want to know about the best industry practices for handling sludge generated from sewage treatment plants. What are the methods for beneficiation implemented from the CAPEX-OPEX perspective.
ONLY by change can the future of human fecal disposal be achieved! Composting toilets NEVER spoken about alternative energy 24/7 NEVER alternative human fecal disposal? Half the cost of building maintaining huge sewage processing plants with pipes that burst the more intelligent approach would be to retrofit every toilet FREE and maintain FREE and still save money. Allowing Big Business to lead society to the future STINKS! Old Man talking.
Unfortunately, there is no real “best” industry standard for wastewater sludge. When it comes to environmental contamination and health problems created by disposing of wastewater sludge, as well as the methane emissions, there really is no intrinsic value to creating wastewater sludge. What the wastewater industry should do is to create wastewater systems that totally eliminate organic wastewater sludge and create wastewater effluent that is 100% re-usable: even potable.
Hi Anvar, this is a big question to answer as it depends on several variables.
In essence your sludge strategy and legal compliance commitments need to be considered.
One of the biggest costs associated with sludge management is the transportation cost, whether the sludge is being discarded to landfill (globally being discouraged and/or outlawed), to incineration or transported to land applications (agriculture). From this point of view, volume reduction is paramount.
To achieve volume reduction, increased volatile solids reduction and dewatering of excess moisture will contribute.
Health risks associated with sludge are high since the digested sludge will still contain ascaris and faecal coliforms as two main pathogens. These should be eliminated to mitigate health and pollution risks
Digested sludge is typically still odorous, by increasing volatile solids reduction, odour can be reduced
By increasing dewaterability and volatile solids reduction, sludge behaviour in terms of stacking, handling etc is improved.
Beneficiated sludge presents huge benefits in land application where carbon, nutrients, microbes will contribute to general soil health and promote fertile soil for crop cultivation
Biogas utilisation form digestion can be utilised and can offset electricity costs by embedding energy through CHP or provided as an alternative to off site LPG use
Adequately applied digestion can have a significant impact on reducing CO2e emissions and reduce GHG's and carbon footprint, across the spheres of wastewater treatment plant site, transportation of solids and application at agriculture site
This has been proven in practice at several established sites applying Thermal Hydrolysis, I know that Thames Water, City of Oslo, United Utilities and DC Water are large entities benefitting from applying Thermal Hydrolysis as an advanced anaerobic digestion step and is worth considering for sites where sludge handling approaches a threshold of probably 50tDS/day and more - economies of scale will influence and so strategy should inform outcomes.
Smaller sludge volumes will most likely still support composting as an alternative, although again a strategy may inform the benefit of regional sludge centres that can then justify advanced anaerobic digestion.
Bottom line, what does the sludge strategy conclude and what quality of sludge is then best? Capital and operating costs will obviously also influence decision making, with a strategy that identifies drivers and costs helping to determine best fit.
Hope this helps, if you need additional information you are welcome to drop me an email, gary@dikubu.co.za
Sludge basically is the consolidated organic matter and therefore it serves best as one of the biomass fuel for power generation. Many have adopted this with greater benefit, please.
Thank you Shyam Ji. can you share few example where sludge is used as power generation. I have search about incineration but could not find link to power generation.
Normal method followed is to centrifuge the sludge to remove the supernatant and the dry sludge is subjected to heat or natural drying to make in to solid blocks to be reycled or disposed in Engineered landfills according to the nature of the sludge composition.
