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Analele Universitii Constantin Brncui din Trgu Jiu, Seria Inginerie, Nr. 2/2010

Annals of the Constantin Brncui University of Trgu Jiu, Engineering Series, Issue 2/2010

71

STUDIUL INDICATORILOR DE

CALITATE AI UNEI APE UZATE

DIN LOCALITATEA MOTRU

Prof. univ. dr. Gheorghe GMNECI Universitatea Constantin Brncui din

Trgu-Jiu

Conf. univ. dr. ing. Camelia CPN

Universitatea Constantin Brncui din Trgu-Jiu

REZUMAT n lucrare se prezint determinri fizico

chimice ale apelor uzate provenite de la staia de epurare a apei din localitatea Motru. n prezent, folosirea raional a resurselor de ap i protecia mpotriva polurii i epuizrii constituie o prioritate internaional.

Analizele fizico chimice au constatat n determinarea indicatorilor caracteristici apelor uzate la ieirea din staia de epurare: temperatura, pH-ul, materii n suspensii, consumul biochimic de oxigen la 5 zile CBO5, consumul chimic de oxigen (metoda cu bicromat de potasiu), reziduul fix, azotul amoniacal, fosforul total i detergeni conform legislaiei n vigoare. Indicatorii de calitate fizico chimici urmrii se ncadreaz n limitele prevzute de Normativul 001/2002, dar excepii fac: amoniacul, fosforul i detergenii care prezint uoare depiri la evacuare n perioada primvar var.

Cuvinte cheie: rezidual, ape, tratament,

poluare 1. INTRODUCERE n cadrul oraului Motru este

prevzut, executat i funcioneaz n sistem separativ reeaua de canalizare ape uzate menajere i ape pluviale.

Apele uzate menajere sunt cele

STUDY OF QUALITY INDICATORS

OF RESIDUAL WATER FROM

MOTRU

Prof. PhD Gheorghe GMNECI Constantin Brncui University of

Trgu-Jiu

Assoc. Prof. PhD Eng. Camelia CPN

Constantin Brncui University of Trgu-Jiu

ABSTRACT The paper presents physical-chemical tests

of residual waters resulted from water treatment plant from Motru. At present, the rational use of water resources and protection against pollution are an international priority.

The physical chemical tests consisted in the determination of the characteristic indicators of residual waters at their release from the treatment plant: temperature, pH, suspended matters, biochemical oxygen consumption 5 days CBO5, chemical oxygen consumption (potassium dichromate method), fixed residual matter, ammonia nitrogen, total phosphor and cleansers according to the relevant legislation. The physical chemical quality indicators are within the ranges provided by the Normative 001/2002, with the following exceptions: ammonia, phosphor and cleansers which record small excesses during the spring summer period.

Keywords: residual, waters, treatment,

pollution 1. INTRODUCTION Motru city is provided with a

residual sewage and rain waters drainage network which is executed and operates as a separate system.

Residual sewage results from all the institutions of water needs of the



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provenite din totalitatea instituiilor cerinei de ap ale obiectivelor care compun folosine de ap.[1-5]

n general, apele uzate menajere provin de la urmtorii consumatori:

- blocuri de locuine; - cldiri socio-culturale; - cldiri socio-edilitare; - ateliere ntreinere i reparaii. Cldirile social-culturale (Casa de

Cultur, club etc.) sunt dotate cu grupuri sanitare compuse din WC-uri, lavoare, duuri, ale cror ape uzate rezultate sunt evacuate n aceeai reea de canalizare.

Apele uzate menajere provenite de la cldirile social-edilitare (liceu, spital, cantin etc.) sunt preluate de aceeai reea. Cele provenite de la cantin, spital, spltorie, nainte de a fi preluate de reeaua principal, vor fi trecute printr-un separator de grsimi i spum pentru separarea suspensiilor.

Apele menajere evacuate de la atelierele aparinnd Sucursalei Motru a RAL Tg-Jiu, Fabrica de tricotaje, sunt colectate ntr-o reea separat i racordat tot la colectorul principal al oraului, avnd acelai coninut de suspensii, nscriindu-se n aceiai parametrii cuprini n normele n vigoare. Reeaua este executat din tuburi de beton cu diametrul de 200-500 mm, colectorul principal avnd diametrul de 700 mm, astfel nct poate prelua ntreg debitul de evacuare de 33,4 L/s.

Reeaua este subteran i se afl la o adncime de 1,3 m i cu pant de scurgere.

Pe traseu sunt prevzute cmine de vizitare la o distan maxim de 50-60 m, n scopul interveniei mai eficiente n caz de colmatare.

Dup colectare, apele sunt conduse ctre staia de epurare oreneasc, amplasat pe malul rului Motru.

n aceast lucrare se prezint studiul indicatorilor de calitate ai unei

objectives included in water uses. In general, residual sewage results

from the following consumers [1.5]: - block of flats; - socio-cultural buildings; - socio-public buildings; - maintenance and repair

workshops. Socio-cultural buildings (Culture

House, club etc.) are provided with sanitary facilities consisting of WC rooms, washstands, shower rooms whose sewage are discharged in the same drainage network.

The residual sewage resulted from the social-public buildings (highschools, hospital, canteen etc.) are taken over by the same network. The sewage resulted from canteens, hospitals, laundry, will pass through a fat and foam separator for separating suspensions before being taken over by the main network.

Residual sewage discharged from the workshops which belong to Motru Subsidiary of RAL Tg-Jiu, Knitted Works Factory are collected in a separate network connected to the main collector of the city, having the same content of suspensions and being recorded within the same parameters provided by the relevant regulations. The network is made of concrete pipes having a diameter of 700 mm, in order to receive the entire discharge flow of 33,4 L/s.

The network is underground and is located at 1,3 m depth and is provided with a drainage slope.

The itinerary is provided with inspection pits at distances of 50-60 m, for an efficient intervention in case of silting.

After catchment, waters are directed towards the municipal treatment plant located on the shore of Motru river.

This paper presents the study of quality indicators of the sewage in Motru and reveals the need to modernize the already existing treatment.



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ape uzate din localitatea Motru i se aduce n prim plan necesitatea modernizrii staiei de epurare, deja existent.

2. EXPERIMENTAL Analizele fizico chimice au

constatat n determinarea indicatorilor caracteristici apelor uzate la ieirea din staia de epurare: temperatura, pH-ul, materii n suspensii, consumul biochimic de oxigen la 5 zile CBO5, consumul chimic de oxigen (metoda cu bicromat de potasiu), reziduul fix, azotul amoniacal, fosforul total i detergeni conform legislaiei n vigoare.

3. REZULTATE I DISCUII Pe baza rezultatelor obinute la

indicatorii de baz, respectiv CBO5, CCOCr i materii n suspensii, s-a calculat randamentul staiei de epurare, aplicndu-se urmtoarea formul:

100M mM

= (1) unde:

M - concentraia substanei la intrarea n staie;

m - concentraia substanei la ieirea din staie.

2. EXPERIMENTAL The physical chemical tests

consisted in the determination of the characteristic indicators of residual waters at their release from the treatment plant: temperature, pH, suspended matters, biochemical oxygen consumption 5 days CBO5, chemical oxygen consumption (potassium dichromate method), fixed residual matter, ammonia nitrogen, total phosphor and cleansers according to the relevant legislation.

3. RESULTS AND

DISCUSSIONS Results achieved for the main

indicators, respectively CBO5, CCOCr and suspended matters allowed to calculate the output of the treatment plant, by applying the following formula:

100M mM

= (1)

where:

M substance concentration at the plant inlet;

m - substance concentration at the plant outlet.



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Figura 1. Influena temperaturii asupra randamentului staiei pentru CBO5 i CCOCr Figure 1. Temperature influence on plant output for CBO5 and CCOCr

Rezultatele obinute experimental sunt prezentate n figura 2 i n tabelul 1.

Experimental results are presented in figure 2 and table 1.

Figura 2. Randamentul staiei (%) pentru CBO5, CCOCr

Figure 2. Plant output (%) for CBO5, CCOCr

Tabelul 1. Caracteristicile fizico-chimice ale apei uzate Indicatori fizico -

chimici

UM Data prelevrii Valori limit

admise conf.

NTPA 001/2002

12.03.2009 16.06.2009 13.08.2009 9.12.2009

Intr. le. Intr. le. Intr. le. Intr. le.

Temperatura C 16,5 16,5 18 18,5 23 23 21 20,5 35

pH Unitate pH 7,7 7,3 7,6 7,3 7,6 7,2 7,8 7,6 6,5-8,5

Materii n

suspensie

mg/dm3 49 46 54 51 40 38 47 43 60

CB05 mgO2/dm3 57,5 54,3 26,2 24,4 29,4 27,2 31,5 29,2 25

CCOCr mgO2/dm3 128 120 69 60 77 64 80 73 125

Azot amoniacal

NH3

mg/dm3 2,7 1,5 2,3 1,7 3,4 1,7 20 1,2 3,0

Fosfor total P mg/dm3 - 0,19 - 2,06 - 1,5 - 1,24 2,0



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Detergeni

sintetici

mg/dm3 - 0,34 - 0,15 - 0,52 - 0,13 0,5

Reziduu fix mg/dm3 185 209 223 262 272 272 134 179 2000

Table 1. Sewage physical-chemical characteristics

Physical

chemical

indicators

MU Sampling date Maximum

rated values

according to

NTPA

001/2002

12.03.2009 16.06.2009 13.08.2009 9.12.2009

Inlet Outlet Inlet Outlet Inlet Outlet Inlet Outlet

Temperature C 16,5 16,5 18 18,5 23 23 21 20,5 35

pH pH unit 7,7 7,3 7,6 7,3 7,6 7,2 7,8 7,6 6,5-8,5

Suspended

matters

mg/dm3 49 46 54 51 40 38 47 43 60

CB05 mgO2/dm3 57,5 54,3 26,2 24,4 29,4 27,2 31,5 29,2 25

CCOCr mgO2/dm3 128 120 69 60 77 64 80 73 125

Ammonia

nitrogen NH3

mg/dm3 2,7 1,5 2,3 1,7 3,4 1,7 20 1,2 3,0

Total Phosphor P mg/dm3 - 0,19 - 2,06 - 1,5 - 1,24 2,0

Synthetic

cleansers

mg/dm3 - 0,34 - 0,15 - 0,52 - 0,13 0,5

Fixed waste mg/dm3 185 209 223 262 272 272 134 179 2000

pH-ul apelor uzate influeneaz sensibil activitatea enzimatic a microorganismelor implicate n procesul de epurare.

Procesele de epurare biologic se pot realiza n limite destul de largi ale pH-ului apelor uzate (6,5-8,5), dar desfurarea optim a unor procese are loc n limitele de pH = 7,0-7,5.

Sewage pH sensitively influences the enzymatic activity of microorganisms involved in the treatment process.

Biological treatment processes can be developed within broad ranges of sewage pH (6,5-8,5), but the optimal development of some processes is made within pH ranges = 7,0-7,5.

In the case of sewage from Motru,



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n cazul apelor uzate din localitatea Motru, pH-ul a nregistrat valori cuprinse ntre 7,6-7,86 la intrare n staie i 7,22-7,63 la evacuare n emisar.

Materiile n suspensie influeneaz procesul de epurare mai ales din punct de vedere funcional.

Concentraii ale materiilor n suspensie mai mari 80-120 mg/dm3 fac s creasc concentraia de nmol n bazinele de aerare, ducnd la colmatarea acestora.

n cazul materiilor n suspensie randamentul staiei de epurare a fost ntre 61.1% n luna martie i 70.4% n luna iunie.

Consumul biochimic de oxigen la 5 zile (CBO5) i consumul chimic de oxigen prin metoda cu bicromat de potasiu(CCOCr), exprim concentraie substanelor organice coninute n apa uzat.

Determinarea gradului de ncrcare organic a apelor uzate la intrarea n staia de epurare indic valori cuprinse ntre 686-82,1 mgO2/L pentru CCOCr i 49,6-71,1 mgO2/L pentru CBO5.

Valorile raportului CBO5/CCOCr pentru apa evacuat sunt prezentate n figura 3.

pH has recorded values between 7,6-7,86 at the plant inlet and 7,22-7,63 at the outlet in the collector.

Suspended matters influence the treatment process especially from functional point of view.

Concentrations of suspended matters higher than 80-120 mg/dm3 result in the increase of the mud concentration in the aeration basins, leading to their silting.

In the case of suspended matters the output of the treatment plant was between 61.1% in March and 70.4% in June.

The 5-day oxygen consumption (CBO5) as well as the chemical oxygen consumption through the potassium dichromate method (CCOCr), express the concentration of the organic substances from the waste water.

The determination of sewage organic load at the inlet in the treatment plant indicates values between 686-82,1 mgO2/L for CCOCr and 49,6-71,1 mgO2/L for CBO5. The values of the CBO5/CCOCr ratio for discharged water are presented in figure 3.

Fig. 3. Variaia raportului CBO5/CCOCr pentru apa evacuat / Figure 3. Variation of the CBO5/CCOCr

ratio for discharged water



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4. CONCLUZII Studiile ntreprinse n cursul anului

2009 privind epurarea apelor n localitatea Motru au condus la urmtoarele concluzii:

1. Valorile raportului CBO5/CCOCr atribuite pentru apa uzat la ieirea din staie indic prezena a substanelor organice uor biodegradabile. n conformitate cu Normativul NTPA 001/2002 privind stabilirea limitelor de ncrcare cu poluani a apelor industriale i oreneti la evacuarea n receptorii naturali, indicatorii urmrii se ncadreaz n mare parte n aceste limite. Excepie fac amoniacul, fosforul i detergenii, care prezint uoare depiri la evacuare n perioade primvar - var.

2. Influena temperaturii sczute a apei s-a manifestat prin reduceri temporare ale eficienei de epurare a instalaiilor, lucru evideniat mai ales n cadrul treptei biologice de epurare. Randamentul cel mai mare s-a nregistrat la temperatura de 23 C. Valorile mai mari obinute pentru consumul biochimic de oxigen i consumul chimic de oxigen indic predominaia materiilor organice biodegradabile n ap.

4. CONCLUSIONS The studies made in 2009

regarding water treatment in Motru have resulted in the following conclusions:

1. The values of the CBO5/CCOCr ratio assigned to residual water at the outlet from the plant indicate the presence of easily biodegradable organic substances. In accordance with the Normative NTPA 001/2002 for determining the load maximum values with industrial and municipal polluting agents at the discharge in natural receptors, the indicators are mostly within these maximum values. There are several exceptions: ammonia, phosphor and cleansers which record small excesses during the spring summer period.

2. The influence of low water temperature could be seen in temporary decreases of plants treatment output, which is especially revealed within the biological treatment stage. The greatest output was recorded for the temperature of 23 C. The higher values resulted for the biochemical oxygen consumption indicate the predominance of biodegradable organic matters in water.



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BIBLIOGRAFIE 1. Antoniu, R. i colab., Epurarea

apelor uzate industriale. Editura Tehnic, Bucureti, 1987

2. Negulescu, M., Epurarea apelor uzate oreneti, Editura Tehnic, Bucureti, 1978

3. Negulescu, M., Secara, E., Exploatarea instalaiilor de epurare a apelor uzate. Editura Tehnic, Bucureti, 1976

4. Rojanschi, V., Bran Florina, Gheorghia Diaconu, Protecia i igiena mediului. Editura economic, Bucureti, 2000

5. Rojanschi, V., Ognean, T., Cartea operatorului din staii de tratare i epurare a apelor, Editura Tehnic, Bucureti, 1989

BIBLIOGRAPHY 1. Antoniu, R. i colab., Industrial

sewage treatment. Technical Press, Bucharest, 1987

2. Negulescu, M., Municipal sewage treatment, Technical Press, Bucharest, 1978

3. Negulescu, M., Secara, E., Operation of sewage treatment plants. Technical Press, Bucharest, 1976

4. Rojanschi, V., Bran Florina, Gheorghia Diaconu, Environmental protection and hygiene. Economic Press, Bucharest, 2000

5. Rojanschi, V., Ognean, T., The book of the operator of waters treatment plants, Technical Press, Bucharest, 1989

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