A.I.Musayev, S.T. Duysenbayeva, R.T.Turegeldieva
M.Kh.Dulaty TarSU, Taraz, Kazakhstan

EVALUATION OF FERTILIZING PROPERTIES OF WASTE WATERS IN SOUTHERN KAZAKHSTAN

Mechanical structures and then artificial biological cleaning are not completely free from sewage pollution. Not less 10-20% of pollution and under impeccable work of treatment facilities the most persistent organic compounds is remaining among them. Any violation of their work condition - overloading, poor maintenance, etc. increases the percentage of residual contamination more. (Table1).

Table 1 - The degree of wastewater treatment

Method of biological cleaning	Degree of cleaning, %
	BPK 5	Nitrogen (N)	Phosphor ( Р2О5)	Potassium ( К2О )	on bacteria
Artificial	86,7	37,5	29,3	18,0	94,5
Soil	94.3	81,6	96,6	76,7	97,1
How many times soil cleaning is more perfect than artificial	1.1	2,2	3,3	4,3	1,03

These data also confirms the high efficiency of soil wastewater treatment. At the same time in the fields of irrigation, recycle of municipal wastewater occurs simultaneously with additional cleaning as a source of moisture and fertilizing substances for growing crops.

Consequently, under conditions of Southern Kazakhstan, wastewaters are not only a source of irrigation water, but valuable fertilizer as well. It is estimated that fertigation effect of urban wastewater in an amount 2000 m/h is equal to the 2 c. of ammonium nitrate, 1.5 c. of potassium chloride and 0.5 c of superphosphate.It is also important that the wastewater nutrients are in dissolved, well assimilable for plant and fed into the soil together with water. The soil is enriched with nitrogen, phosphorus, potassium and other essential elements of plant nutrition.

Only in domestic (urban) wastewater of republic, according to preliminary data, 10,600 tons of nitrogen, 3,600 tons of phosphorus and 9,500 tons of potassium are contained, which more than 300 hectares of farmland could be fertilized. Consequently, one of the main agromeliorative and ecological indicators under agricultural wastewater utilization in pouring farmland is the evaluation of their fertilizing properties.

As there are two kinds of wastewater irrigation: humidifying and fertigation are held by wastewater with high concentrations of nutrients (livestock, waste water, and enterprises’ drains of the food industry).

According to the developed world classification (WPC 32-2.2-86), fertilizing value of urban wastewater, gone a full biological treatment with the content of nutrients: nitrogen <50, Phosphor <10 and Potassium <30 mg / L - refers to the low III group. We have been studying the fertilizing properties of Almaty wastewater since1976.

At the beginning of the research period (1976-1980 years) only mechanical cleaning was operated at the city sewage treatment, after which the waste water was discharged into the storage device of Zhamankum. During this period, the quality of wastewater was investigated after cleaning constructions and in pond storage device of wastewater in Burundaisk farms as well. (Table 2).

Table 2 - Fertilizer properties of Almaty wastewater (1976-1980 y.) and after mechanical cleaning, mg / l

Item of sampling	Nitrogen (N)	Phosphor (Р2О5)	Potassium (К2О)
After cleaning constructions (mechanical)	30,6-36,1	7,1-10,4	16,5-18,4
Storage pond of Burundaisk farm mg / l /% reduction	18,5-26,4 40-27	2,6-4,6 60-55	8,6-12,3 48-33

From the comparison of fertilizing properties of wastewater after cleaning constructions and in storage pond (accumulation period of 5-6 months is not growing season) is seen that a storage pond was self-purification of nitrogen to 27-40%, phosphorus - by 55-60% and potassium at 33-48%.

The magnitude of COD was decreased from 200-250 to 33-55 mg / l BPK - from 119-150 to 17-43 mg / l. It is explained that the storage pond together with water regulation, acts as a biological pond. However, fertilizing quality of wastewater is remained in Category III. The station of biological cleaning is put into operation since 1980. Indicators of fertilizing properties are shown in Table 3.

Table 3 – Indicators of fertilizing properties of Almaty wastewater, mg / l (after biological cleaning, 1986-1991 and 1999-2012 y.)

Item of sampling	Nitrogen		Phosphor		Potassium
	1986-1991	1999-2012	1986-1991	1999-2012	1986-1991	1999-2012
water divider (discharge canal)	21,4-29,2 30-20	10-16,1 65-55	4,6-6,1 35-40	2,2-2,8 70-73	9,4-12,6 23-32	7,8-9,9 53-46
Sorbulak	26,8-27,2	16,6-26,8	6,8-7,1	2,7-6,8	13,0-13,4	8,8-13,4

Comparison of the data table shows that after the biological cleaning, there is some reduction in fertilizing properties of sewage: nitrogen - by 20-65%, phosphorus - by 35-70% and potassium - by 23-53%. While there is a big difference over the years. So, if before 1984 the cleaning effect of the biological station does not exceed 50%, by 1995 it has reached up to suspended solids 95%, BPK - 92% by 2000 – by suspended solids - 96%, BPK - 89.5 and COD - 92.3%.

Improvement of biological cleaning constructions and other facilities allowed bringing the degree of purification to the desired level. However, as noted above, and in these circumstances there is residual contamination by organic substances.

Table 4 - The loss of nutrients and organic mass at different methods of wastewater cleaning (K. Stehlik, Czechoslovakia, 1972)

The nutrients	Decline of nutrients, in%
	By mechanical cleaning	By mechanical, biological cleaning of activations	By mechanical biological cleaning on biofilters	In oxidizing canals
Nitrogen, total	10-30	25-45	40-55	10-50
К2О	0-10	0-10	0-10	0-10
К2О	25-35	35-45	not conducted
Organic mass	30-44	40-60	not conducted

Loss of nutrients is noted in other studies by various cleaning methods.

Table 5 - Comparative effectiveness of various methods of domestic wastewater cleaning, % (E.I.Goncharuk, 1976)

Methods for cleaning up	Diminution
	BPK5	Suspended solids	Bacterial number
mechanical	30-35	50-60	40-50
Biological (on biological filters for activated sludge plants)	70-80 75-85	70-80 85-90	85-90 90-95
In the fields of irrigation	90-95	90-95	90-95

Under comparing the amount of nitrogen, phosphorus and potassium after cleaning constructions with its quantity in Sorbulak lake’s composition (until 1988 Zhamankum storage device was acted, which was stopped to be existed as the result of breakthrough of wastewater into Kaskelen river) and in pond storage facilities of Burundaisk, the amount of nitrogen and phosphorus is traced to be decreased and the significant changes in content of potassium were not observed (Table 6).

Table 6 - Fertilizer properties of Almaty wastewater in various years of research, mg / l

Item of sampling	Period	Indicators
		Nitrogen (N)	Phosphor (Р2О5)	Potassium (К2О)
After mechanical cleaning in diverting canal	1976-1980	33	26	12
After biological cleaning in diverting canal	1980-1990	29,2	6,11	12.6
	1990-2000	16,1	4,5	11,8
	2001-2002	17,7	3,4	13,2
Lake Sorbulak	1980-1990	27,1	6,9	13,2
	1990-2001	18,2	0,55	12,4
	2001-2002	15,1	2,5	11,6
Pond storage device of Burundaisk farm	1976-1980	23,7	3,2	10,6

The significant reduction in fertilizing properties of wastewater in 1990-2000 is connected with the closure of many industrial enterprises in Almaty. Reducing the amount of nutrients in the pond of Burundaisk farm storage and Sorbulak lake was occurred during the transportation of the waste water (to pond storage device of Burundaisk farm - 20-25 km to Sorbulak lake - about 100 km) (4).

Under these conditions, conveying collector is peculiar cleaning construction, wherein the waste water is flowing through it, it is better stirred and increases its dispersion, a number of organic compounds are exposed to hydrolysis. In addition, tertiary treatment of wastewater in pond storage device is flowing in conditions closest to the natural course of the pond self-purification.

It is folded from several independent and interrelated processes: mechanical deposition, bio flocculation, aerobic oxidation, anaerobic decomposition, methane fermentation, photosynthesis, etc.

Analysis and evaluation of fertilizing properties of municipal wastewater in southern Kazakhstan’s cities showed that they all belong to group III with low fertilizing value (Table 7).

Table 7 - Average content of nutrient in urban wastewater of Southern Kazakhstan, mg / l

City	Nitrogen	Phosphor	Potassium
Almaty (after bio cleaning)	33	14	12
Shymkent (after mechanical cleaning)	27	16	15
Taraz (after mechanical cleaning)	38	15	19
Кyzylorda (after bio cleaning)	21	5,2	22

Fertilizer quality of these waters in their content of nitrogen, phosphorus, and potassium cannot have a significant impact on the improvement of soil fertility. Taking into account the lack of nutrients in Southern Kazakhstan, irrigation by municipal wastewater is recommended to combine with the mandatory introduction of the necessary standards of organic and mineral fertilizers. Required dose of fertilizer is calculated on the removal of soil nutrients by plants with regard to their content in irrigation water and soil.

Wastewater of JSC "Kazphosphate" is characterized mainly by an alkaline reaction, low salinity (0.7-0.9 g / l); type of chemistry is unstable over the years. Chemical reactions of wastewater reflect the feedstock, which water is met in the technical industrial processes. Under the group of wastewater suitability for irrigation, they are related to the third group, which requires the flushing regime of irrigation by ensuring drainage with restricted cultures composition.

Ratio of cations is unfavorable; alkalinity of soils possibly refers to the wastewater with low fertilizing value. Content of fluorine, total phosphorus and solubility phosphorus vary within wide limits: fluorine - 2, 7 - 12, 1; fluorine total 13.8 - 85.0; soluble phosphorus - 5, 2-62, 3. Content of fluorine - outside of acceptable content in natural water.

Domestic and industrial sewage of LLP "BM" are treated at full biological cleaning constructions. The degree of BOD5 and COD cleaning comprises 90- 95%, their contents after the cleaning construction corresponds to dirty waters. After the biological cleaning, they are referred to the second type of sulfate class (SO4-Cl-Na). According to the total salt content (1.1-1.6 g / l), it is met the requirements of irrigation water and can be used for irrigation of crops on all soil types.

According to organic substances content (BOD5), it is classified as very dirty water. The ratio of BOD5 and COD equal to 0.4 is close to domestic waters, where the tertiary treatment must expediently be carried out by soil-biological way. Development of alkalinization process sodium is possible in watering according to ratio of cations.

Maintaining of wastewater after cleaning constructions in pond greatly improves their quality indicators: salinity decreases by 2-3 times (0, 45-0, 51 g / l), changing the chemical composition, the water goes to the hydro-chloride-calcium waters (HCO3-Cl-Ca); the ratio of the cations varies in the positive direction.

Consideration of theoretical and experimental researches carried out in different areas of CIS and abroad, was found that by using of weakly mineralized municipal wastewater as irrigation water, the main negative component negatively affects the geochemical regime of the soil is the ratio of cations, especially in sewage of lake Sorbulak.

Increase of sodium content (Na) in the irrigation water may help to displace calcium (Ca) and magnesium (Mg) from soil absorbing complex and to increase the amount of sodium in it (Na), so that there can be soil alkalinization process, but it must be recognized that weak acid anions in the effluent are presented by organic acids which, calcium soil is activated in an appropriate aqueous mode, thereby it contributes to the improvement of water-physical and geochemical properties of the soil.

Conclusions:
1. Urban wastewater is related to domestic waste waters according to the chemical composition and their quality:
- Sanitary - hygienic and irrigation indicators of sewage are improved in pond storage device in the process of natural course of self-purification under influence of biocenosis;

- Urban wastewater is related to III group with low fertilizing value and mandatory required standards of organic and mineral fertilizers are recommended by using it in irrigated agriculture.

List of references:

1. Novikov V.M., Kovaleva N.A., Ovtsov N.P., Dodolina V.T., Musayev A.I.etc. "VSN 33-2.2.022-86 irrigation, MWR USSR, 1986.-85p.

2. Stehlik Kare, Condition and prospects of research on wastewater irrigation in Czechoslovakia / / Agricultural use of sewage: Proceedings of the VI International Meeting of scientists from the socialist countries on the use of wastewater in agriculture - M., 1972. - 170-186 p.

3. Galchenko M.G., Zhelyazko V.I. Wastewater Irrigation. - M., Agropromizdat, 1988. -104 p.

4. Musayev A.I. Formation of return water in water basins of southern Kazakhstan, and evaluation of its suitability for irrigation / / role of reclamation in ensuring of industrial and ecological safety in Russia: Materials of the International Scientific and Practical Conference. Moscow, 2009. - 239 – 245p.