Zootechnical plant
The plant, installed and functioning since 2004, is made up with a first equalization tank, with a solid/liquid mechanical separation phase and with the Microbioflottazione tank. The process of nitrogen removal takes biologically place in this single tank without using any chemicals. Hereunder the flow sheet of a nitrogen_removal plant for the respect of the European Directive 91/676/CEE (Nitrates Directive).
Solid/Liquid Separation
In this treatment phase the manure proceeding from the stables collection (after homogenization in a proper tank) and/or the digested manure from anaerobic process, are discharged to an equalization tank V (HRT = 3÷4days). From the tank V the manure is fed to the treatment phase G. The solid part (8-10% p/p with 25-30% of dry matter) is collected and stored on concrete bed while the liquid fraction is discharged to a pumping tank V0 from where is pumped automatically to the treatment tank of Microbioflottazione.
Microbioflottazione
The following treatment phase is inside a tank V1 where the Microbioflottazione nitrogen removal process takes place.
The tank is equipped with the patented oxygenization system fitted with a proper number of nozzles.
The nozzles are connected to a stainless steel hydraulic network fed by a centrifugal pump which keeps the patented forced aeration system pressurized. The system is able to transfer to the liquid volume held in the treatment tank a specific oxygen quantity according to the oxygen demand and the manure inlet flow rate.
The Microbioflottazione process, in a first aerobic phase, digests the organic load (COD) and nitrifies ammonia to nitrites and nitrates. In a second anoxic phase nitrites and nitrates are reduced, in zero oxygen environment (denitrification), to elementary nitrogen (N 2 is the main air component with 78% v/v) which is released in the atmosphere. The manure with a nitrogen removal by 70÷80% is automatically pumped to the storage tanks from where it is sent to field spreading. Further treatment
The outlet manure from the Microbioflottazione phase can be treated in a following phase. This last phase is designed according to the water treatment and/or recovery necessities:
- Physical-mechanical treatment:
- Description: separation, simple or advanced, of the solid fraction of the manure by sedimentation or filtration;
- Goal: further phosphorous, COD and SS reduction.
- Physical-chemical treatment:
- Description: chemical processes as coagulants and flocculants dosing are combined with physical-mechanical processes as sedimentation or filtration, in order to increase the removal efficiency optimizing the chemicals consumption;
- Goal: further nitrogen, phosphorous, COD and SS reduction.
- Biological-physical-chemical treatment:
- Description: the previous treatment is up-graded with an anaerobic-aerobic-anoxic three phase MBR system;
- Goal: complete purification and water recovery.
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