A study about the use of chemicals in conventional tertiary treatment. Performances comparison of three municipal wastewater treatment plants and pilot plant experiences

2011 ◽  
Vol 6 (1) ◽  
Author(s):  
A. Iborra-Clar ◽  
J.A. Mendoza-Roca ◽  
A. Bes-Pií ◽  
J.J. Morenilla-Martínez ◽  
I. Bernácer-Bonora ◽  
...  

Rainfall diminution in the last years has entailed water scarcity in plenty of European regions, especially in Mediterranean areas. As a consequence, regional water authorities have enhanced wastewater reclamation and reuse. Thus, the implementation of tertiary treatments has become of paramount importance in the municipal wastewater treatment plants (WWTP) of Valencian Region (Spain). Conventional tertiary treatments consist of a physico-chemical treatment of the secondary effluent followed by sand filtration and UV radiation. However, the addition of coagulants and flocculants sometimes does not contribute significantly in the final water quality. In this work, results of 20-months operation of three WWTP in Valencian Region with different tertiary treatments (two without chemicals addition and another with chemicals addition) are discussed. Besides, experiments with a 2 m3/h pilot plant located in the WWTP Quart-Benager in Valencia were performed in order to evaluate with the same secondary effluent the effect of the chemicals addition on the final water quality. Results showed that the addition of chemicals did not improve the final water quality significantly. These results were observed both comparing the three full scale plants and in the pilot plant operation.

2005 ◽  
Vol 51 (12) ◽  
pp. 315-323 ◽  
Author(s):  
L. Wang ◽  
J. Peng ◽  
B. Wang ◽  
R. Cao

An on-site study on the operational performance of a combined eco-system of ponds and SF constructed wetland for municipal wastewater treatment and reclamation/reuse in Donging City, Shandong, China was carried out from January 2001 through October 2003. The removal efficiencies for various main parameters were: TSS 84.8±7.3%, BOD5 87.2±5.3%, CODCr 70.2±18.6%, TP 52.3±23.1%, and NH3-N 54.8±23.9% with effluent concentration of TSS 9.12±5.12 mg/l, BOD5 6.44±4.58 mg/l, CODCr 42.8±6.7 mg/l, TP 0.94±0.27 mg/l and NH3-N 7.95±2.36 mg/l. In addition, the removal efficiencies for faecal coliforms and total bacteria were >99.97% and >99.998% respectively, which well meet Chinese National standards for effluent quality of municipal wastewater treatment plants. The composition of TSS was closely related to CODCr and BOD5 variations, and nitrification-denitrification is the major mechanism of nitrogen removal both in ponds and in wetlands. In addition, sedimentation also played an important role in the removal of TSS, nitrogen, phosphorus and BOD5. The removal efficiencies of various parameters, the number of species and biomass of biological community in the system increased gradually with the ecological maturation.


1992 ◽  
Vol 25 (4-5) ◽  
pp. 289-295 ◽  
Author(s):  
K. R. Imhoff

Since 1913 the Ruhrverband has been responsible for comprehensive water quality and water quantity management in the Ruhr River basin, covering an area of 4,488 km2. In 116 municipal wastewater treatment plants sludges with 59,000 tons of dry solids are annually retained. For the year 2000 a total of 75,000 tons is expected. The paper describes the development of a basin-wide sludge disposal concept under realistic assumptions. As treatment plants of varying sizes are existent, all three applicable routes of sludge disposal must be kept open for the future: 1. agricultural utilization, 2. controlled disposal after dewatering and 3. incineration.


2007 ◽  
Vol 55 (1-2) ◽  
pp. 397-405 ◽  
Author(s):  
R.J. Chiou ◽  
T.C. Chang ◽  
C.F. Ouyang

The Water Resources Agency (WRA), Ministry of Economic Affairs (MOEA) has predicted that the annual water demand in Taiwan will reach approximately 20 billion m3 by 2021. However, the present water supply is only 18 billion m3 per year. This means that an additional 2 billion m3 have to be developed in the next 17 years. The reuse of treated wastewater effluent from municipal wastewater treatment plants could be one target for the development of new water resources. The responsible government departments already have plans to construct public sewerage systems in order to improve the quality of life of the populace and protect the environment. The treated wastewater effluent from such municipal wastewater treatment plants could be a very stable and readily available secondary type of water resource, different from the traditional types of water resources. The major areas where reclaimed municipal wastewater can be used to replace traditional fresh water resources include agricultural and landscape irrigation, street cleaning, toilet flushing, secondary industrial reuse and environmental uses. However, necessary wastewater reclamation and reuse systems have not yet been established. The requirements for their establishment include water reuse guidelines and criteria, the elimination of health risks ensuring safe use, the determination of the wastewater treatment level appropriate for the reuse category, as well as the development and application of management systems reuse. An integrated system for water reuse would be of great benefit to us all by providing more efficient ways to utilise the water resources.


2012 ◽  
Vol 66 (10) ◽  
pp. 2115-2121 ◽  
Author(s):  
M. Boehler ◽  
B. Zwickenpflug ◽  
J. Hollender ◽  
T. Ternes ◽  
A. Joss ◽  
...  

Micropollutants (MP) are only partly removed from municipal wastewater by nutrient removal plants and are seen increasingly as a threat to aquatic ecosystems and to the safety of drinking water resources. The addition of powder activated carbon (PAC) is a promising technology to complement municipal nutrient removal plants in order to achieve a significant reduction of MPs and ecotoxicity in receiving waters. This paper presents the salient outcomes of pilot- and full-scale applications of PAC addition in different flow schemes for micropollutant removal in municipal wastewater treatment plants (WWTPs). The sorption efficiency of PAC is reduced with increasing dissolved organic carbon (DOC). Adequate treatment of secondary effluent with 5–10 g DOC m−3 requires 10–20 g PAC m−3 of effluent. Counter-current use of PAC by recycling waste PAC from post-treatment in a contact tank with an additional clarifier to the biology tank improved the overall MP removal by 10 to 50% compared with effluent PAC application alone. A dosage of 15 g PAC m−3 to a full-scale flocculation sand filtration system and recycling the backwash water to the biology tank showed similar MP elimination. Due to an adequate mixing regime and the addition of adapted flocculants, a good retention of the fine fraction of the PAC in the deep-bed filter were observed (1–3 g TSS m−3; TSS: total suspended solids). With double use of PAC, only half of the PAC was required to reach MP removal efficiencies similar to the direct single dosage of PAC to the biology tank. Overall, the application of PAC in WWTPs seems to be an adequate and feasible technology for efficient MP elimination (>80%) from wastewater comparable with post ozonation.


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