In wastewater treatment, the ...
Published by Jeremy Biddle, Engineering Director at Bluewater Bio
In wastewater treatment, the general principle is to create the right conditions for the reaction you want and the bacteria will sort themselves out. Different reactions require different conditions and many of the enhancements to the basic activated sludge process have focused on adjustments to the operating conditions to make the process more efficient, by selecting for particular types of bacteria and making them work harder.
There's a lot to learn and far too much to put in an online forum so I suggest you refer to a good general wastewater treatment textbook such as "Design & Operation of Activated Sludge Systems" by Nigel Horan, or Metcalf & Eddy's "Wastewater treatment" for more general wastewater treatment methods.
3 Comments
Voici comment : la digestion anaérobie est un processus en trois étapes
Pourquoi le milieu sans oxygène n'arrive t-il pas alors à éliminer les boues d'assainissement. Pourtant avec toutes ces belles théories on devrait être ultra performant.
Here is how: Anaerobic digestion is a three-stage process
Why the Middle without oxygen can't t - he not then to eliminate sludge sanitation. Yet with all these beautiful theories should be ultra efficient.
Un effluent d'eaux usées d'assainissement collectif, est déjà dans un état biochimique. Les bactéries sont rares à moins d'être des super bactéries capables de vivre dans un tel milieu.
Les molécules chimiques provoquent des réactions chimiques qui tuent tout être vivant.
La boue activée n'apporte aucune action de réduction de la matière organique. Cette fonction sert uniquement à réduire les risques d'implosion du liquide sous l’effet d’une forte méthanisation du milieu au point de fissurer les bacs en béton.
Tous les descriptifs de l'assainissement collectif définissent que l'effluent qui arrive sur le site est de la boue. La boue contient plus de 8% de bactéries mortes.
Pour que les micros organismes puissent accomplir leur travail de biodégradation de la matière organique, il ne faut pas que le taux de la population présente dans l’effluent, descende en dessous de 75% puisqu'à ce stade le renouvèlement est déjà compromis. La scissiparité.
Bien entendu on est déjà largement en dessous.
J'ai du mal au vu des débits énormes d'effluents d'eaux usées à traiter des collectifs que l'on puisse:
Bien entendu on est déjà largement en dessous.
J'ai du mal au vu des débits énormes d'effluents d'eaux usées à traiter des collectifs que l'on puisse
1 faire le tri des bactéries les plus efficaces
2 que ces bactéries vivent et travaillent dans un milieu biochimique
3 que le transit, tellement court, puisse laisser y avoir un soupçon de travail de biodégradation
Dans le procédé "Fosse Biologique" lyseconcept le temps de transit est de 12 à 15 jours minimum et dans des conditions totalement -aérobie-.
Dans les conditions générales de fonctionnement des STEP, l'objectif a atteindre n'a jamais été d'éliminer les boues mais uniquement les bactéries, dans le liquide rejeté
English
A mains, sewage effluent is already in a biochemical State. The bacteria are rare unless you are super bacteria able to live in such an environment.
The chemicals cause chemical reactions that kill any living being.
Activated mud brings no action of reduction of the organic matter. This feature is used only to reduce the risk of implosion of the liquid under the influence of a strong methanisation of the middle point of crack the concrete tubs.
All the descriptions of collective sanitation define that the effluent that comes to the site's mud. The mud contains more than 8% of dead bacteria.
Micros organismes are to do their job of biodegradation of organic matter, it is not the rate of the population present in the effluent, drop below 75% since at this point the renewal is already compromised. The eucaryotype.
Of course we're already way below.
I have trouble in view of huge flows of wastewater effluents to treat collectives that can be
I prefer aerobic wastewater treatment, as there are problems with anaerobic microorganisms. Here is how:
Anaerobic digestion is a three-stage process. In the first stage, the complex insoluble organics are hydrolyzed to simple soluble organics by the extra cellular enzymes. During this stage, the cellulose and starch are hydrolyzed to simple sugars, while proteins bifurcate into amino acids. In the second stage, called the acid phase, the acid formers (various species of Pseudomonos, Alcaligens, Flavobacterium, Escherichia and Aerobacter) convert simple organics to organic fatty acids (acetic acid). This results in higher acid concentration and low pH. In the third stage, called methane phase, methane formers utilize the organic acids and metabolized them to methane and carbon dioxide. Amino acids give rise to ammonia, which in turn, neutralize the remaining acids.
Methane formers (species of Methanobacterium, Methanococcus and Methanosarcina) are highly frail in nature. They are strict anaerobes, grow over a wide range of temperature, difficult to cultivate and, they remain inalienable. They are highly sensitive to low pH conditions.
These concomitant reactions in actual digestion occur simultaneously. Flawless performance of the digester will take place only when there is a balanced bacterial population of acid formers and methane formers, or, in other words, the volatile acids production equals volatile acids breakdown. If the volatile acids formation is greater than its breakdown (which usually is the case, in actual digesters), the pH lowers, inhibition or wash-out of methane formers occurs and, the process fails, biologically.
P L McCarty was the one who invented anaerobic contact process in 1964. In 1969, P L McCarty and C J Young developed anaerobic filters. Lettinga invented upflow anaerobic sludge blanket (UASB) in early 1970s. UASB, and to some extent anaerobic filters found some use in India. India has a large 345 million liters per day capacity upflow anaerobic sludge blanket plant, located at Bharwara, Lucknow, Uttar Pradesh. This is the largest UASB plant in Asia.
F H Mughal
Karachi, Pakistan
Published by F H Mughal