Origin of sewage
Ocean disposal was too expensive and the disposal of raw sewage into the Harbour was no longer acceptable. Digitized by Google Books, thanks to Tom Bates for locating and contributing this book.
The decomposition of the algae by bacteria uses up so much of the oxygen in the water that most or all of the animals die, which creates more organic matter for the bacteria to decompose.
Small filter-feeding invertebrates such as Daphnia and species of Rotifera greatly assist in treatment by removing fine particulates.
Phosphorus removal can also be achieved by chemical precipitationusually with salts of iron e.
The development of septic tanks offered even more progress in this quest for processes that required less and less space. The establishment of the profession of sewerage or public health engineering allowed the domination of the debate by a group of people with common goals and approaches and facilitated the formation of the consensus that was necessary for a paradigm to be formed.
From cholera to modern sanitation Print from that shows the danger of the filtering of waste water into the drinking water wells due to the unsealed joints of the pipes.
Origin of sewage
One disadvantage is that chlorination of residual organic material can generate chlorinated-organic compounds that may be carcinogenic or harmful to the environment. Such process steps mainly consist of activated carbon filters that adsorb the micropollutants. In many places, particularly at ocean outfalls, one stage processes were installed and sedimentation was definitely cheapest if that was all you were installing. The story of our sewers is a turbulent, mixed-up history of bad decision after bad decision that has brought us to a horrible relationship between ourselves and our wastes. These beds were each flooded with effluent in rotation and, while not in use, they were cultivated with the sewage sludge which was ploughed into them. Collected sludge was either used as fertilizer or simply buried. This together with trickling filters became the staple methods used by engineers for secondary treatment. In some cities, waste water simply ran down the streets, which had stepping stones to keep pedestrians out of the muck, and eventually drained as runoff into the local watershed. The Commission reported on these methods in their fifth report under the heading of "Preliminary Processes" and they stated, The evidence which we have received and our own experience show that it is generally more economical to remove from the sewage, by a preliminary process, a considerable proportion of the grit and suspended matter, before attempting to oxidize the organic matters on land or in filters. It is also particularly important for water reuse systems where high phosphorus concentrations may lead to fouling of downstream equipment such as reverse osmosis. Second, waste recycling: promote low-cost, on-site technologies like composting toilets. The first sanitation system was found in the prehistoric Middle East and the surrounding areas.
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