AGRICULTURAL ASSESSMENT FOR THE SAFE USE OF THE TREATED SEWAGE AND SLUDGE UNDER DIFFERENT TREATMENT SYSTEMS

Abstract

This study includes environmental risk evaluation for wastewater treatment systems used in Egypt and this study was carried out on many stages: 1- Evaluation of wastewater treatment systems Activated sludge (AS) the study was carried out of 5 WWTPs Tookh, El-Zagazyg, Tanta, Elmansoura and New Demietta, Trickling filter (TF) the study was carried out of 4 WWTPs El- korain, Samanood, Shebeen-El-kom and El-Hamool, Oxidation ditch (OD) the study was carried out of 3 WWTPs in Abo-metana, Samool and Kaser-Rashwan and Oxidation ponds (OP) the study was carried out Sarabum WWTP, governorates, respectively. The study was carried out for treatment stages including (raw and treatment wastewater) by assessing both pH, TSS, COD, BOD and some heavy metals Ni, Zn, Cd, Pb and Cu and this was during the period from January 2012 till December 2012 to determine the efficiency of pollutants removal and also quality of treatment wastewater and the extent of its compliance to the allowed limits according to the qualification and criteria mentioned in law. No. 48 for year 1982 From the previous study, it is clean that the designing of plants and the treatment methods has high efficiency but the deficiency of treatment refers to:- 6- Increase of the actual capacity than the designed capacity of the plant. 7- The type of the wastewater which enters the plant does not fit with the treatment methods. 8- The increase of the organic load and the industrial waste which enters the plant does not fit the treatment methods. 9- The human factor is not available and not even which decrease the operating efficiency of the plant. 10- It is observed that the best treatment methods activated sludge, although the designed capacity is more than the actual capacity. 2- Evaluation of drain Water before and after using crops residues (rice straw) A study was conducted for the Agricultural drain water of the Tookh WWTP and operating with Activated sludge system this drain. The use of plant residues (rice straw) as a kind of biological treatment and utilization of rice straw to decrease organic pollutants and some heavy metals in drain water. The rice straw was put at different distances 500 m - 2 km - 5 km and in the period of time from (November 2012 until March 2013). Samples were taken from the point of meeting the WWTP with the drain water and also samples were taken at the above mentioned distances before and after the putting of rice straw. The results showed that the values decrease when moving away from source of pollution and showed the effectiveness of rice straw as a filter for the drain water, as well as the accumulation of pollutants at rice straw piles led to a decline in the proportion of organic pollutants and some heavy metals in drain water as shown in following results 178,170, 109,4.20 , 3.94 ,1.25 , 3.91 and 7.03 mg / L at point of meeting the treated wastewater with drain water respectively, and the results were as follows at 5 km 38, 40, 27, 1.63, 1.29, 0.24, 0.66 and 2.49 mg / l for both of TSS, COD, BOD, Ni, Zn, Cd, Pb and Cu.