Page 70 - March 2020 - WT Site

Sustainable Integrated Decentralized

Waste Management

By Dr. D. N. Ravi Shankar

eneration of the liquid waste (sewage) and bio- be grinded with recycled water of the STP and made into liquid
degradable solid waste (food waste) is inevitable in waste and can be fed into an anaerobic digester integrated in
Gany community. Scientific disposal of both wastes the STP civil structure itself. Hence, both food waste and liquid
is mandatory by the community like apartments, industries as waste will produce biogas that can be used for many beneficial
per pollution control board norms. Generally in most cases purposes.
food waste is composted and liquid waste is treated in various
technologies. Part of the treated water is reused for toilet flushing Anaerobic technologies have many advantages like less sludge
and gardening and rest is let out to drains. Anaerobic technologies production, higher organic loadings, less footprint, produce
produce biogas which can be used for various purposes like biogas and energy positive. Hence, introduction of anaerobic
cooking, power generation, etc. Hence combination of anaerobic technologies will reduce overall foot print and power for the
and aerobic technologies if are used in the process flow has many entire STP as a whole.
advantages and will be a sustainable option for scientific disposal
and reuse of both wastes. There are several case studies to that Aerobic technologies use oxygen available in the air as an
extent. oxidising agent and degrade BOD into carbon dioxide, water and
biomass. This addition of oxygen requires power for blowers and
Introduction diffusers which require a lot of power. Since major pollution (70
to 75 per cent) will be removed in anaerobic technologies, aerobic
Anaerobic degradation liquid wastes like septic tanks are century technologies will have lesser pollution to remove. This optimises
old. Lots of improvements have occurred in the last three the power and foot print of the integrated waste handling facility.
decades in the anaerobic technologies. In case of liquid waste
the effluents of the anaerobic technologies do not meet the There are many anaerobic technologies like anaerobic baffle
mandatory standards, but still majority of the BOD/COD could reactor, anaerobic contact process, up-flow anaerobic sludge
be removed with production of the biogas. The effluents of the blanket reactors and several modifications of the above said
anaerobic technologies can be subjected to aerobic degradation processes. Multiple aerobic technologies are available like
to meet the mandatory treated water standards. Food waste can activated sludge process and its modifications, trickling filters and

72 Water Today - The Magazine l March 2020