Waste Water Refinery in West of Mashhad
the refinery system in this refinery is air giving lagoon with complete mixture. This refinery is located in the southern border of the seasonal river of Kashafrood in the north-west of Mashhad in a 10 kilometer distance from Azadi square. The waste water gathered from the western sections is led to this refinery by a transfer line with the length of 9 kilometers made of reinforced concrete with the oval cross-section with the dimensions of 90 * 135 centimeters. The priority of gathering and refining the waste water of Mashhad is given to this section because the major wells of drinking water are situated in Ghasem Abad.

Different Units of The Refinery

  ● garbage separation unit
  ● current measurement unit
  ● biologic refining unit – air giving lagoon
  ● settling unit
  ● complementary and polishing unit
  ● chloral adding unit
 

Process of Refinery

   ► Garbage separation unit:
In this unit (manual and mechanical) is the first part. It consists of two canals; in the main canal the equipments of mechanical garbage separation and equipments of the garbage are installed, and the minor canal is predicted for manual garbage separation. The cleaning system is that of rotating metal hook and after gathering the garbage while rotating, it is cleaned by a scraper blade.
The gathered garbage are emptied behind a garbage collector in a helical protractor that is simultaneously and automatically activated and empty the garbage in special containers. The amount of the garbage gathered in the place of garbage collector is 0.3 to 0.4 cubic meters per day that is buried daily.
 

   ► Air giving Pools:
The air giving pools in the refinery are of the complete mixture kind. There are 2 of these pools and the time of stay in them is 5 days and the total volume of each pool is 38000 cubic meters. Waste water enters the pool from 3 transversal hatches and exits the pool through another adjustable hatch. In each lagoon, there are 20 air givers that in addition to oxygenating the waste water prepare the condition of complete mixture. That is why the arrangement of the air givers are in a way that the direction of each of them is opposite of the one next to it.
 

   ► Settling Pools:
In waste water refining systems with the method of lagoon, to separate the solid floating material in the exit of air giving lagoons, settling pools are used. There are 2 settling pools and the time of stay in them is 2 days and the total volume of each pool is 152000 cubic meters that are dredged each 4 year.
 

   ► Polishing Pools:
To complete the waste water system by omitting microbus factors and increasing the efficiency of the system through elimination of floating germs, a polishing pool is used most of the times. The time of stay in these pools is 4days and the total volume of the pool is 60800 cubic meters.
 

   ►  control and equipments room:
● Table of control equipped with miniature fuses, signal lamps, fungous step buttons, step and start buttons.
●  Power panels equipped with cartridge fuses, contactors, over load and phase control.
 

Control room with the mentioned equipments along with the switch gears equipped with starters and step buttons, are responsible for the function of the air givers placed near the air giving lagoons in a way that each day the current of each of the air givers, coming voltage and the total current of the air givers of each pool is measured and kept.
 

   ►  Laboratory of the refinery of Parkand Abad:
The tests which are being taken in the laboratory of Parkand Abad at the moment are: registering the appearance of the samples, measuring the temperature of the environment and the sample, measuring PH, alkali ness, electrical conduct of the solid materials( both stable and volatile solids), all the floating solids( stable and volatile), all the solid solutions( stable and volatile), total and solution BOD, total and solution COD, volume andis, SIV slime, the ability of settling, parasite eggs, phosphate and solphid ion, and turbid ness that these tests are done on three compound sample which are taken from the entering of the refinery, the exit of air giving lagoons and the exit of the refinery in these hours: 2, 7, 12, 17, 22.

   ► The present exploitation condition of the Parkand Abad refinery:
At present the coming waste water to this refinery consist of human waste water and some of the waste water of the industrial estate of Toos (located in the north-
west of Mashhad). To confirm the refining efficiency and quality recognition of the coming waste water, there are some factors that are measured daily (for the
coming the compound sample in hours: 7, 12, 22, 2 and for exiting a simple sample), and are kept in related charts. The private sector is in charge of this
refinery with satisfactory results.