Dataset on the cost estimation for spent filter backwash water (SFBW) treatment

The dataset presented in this article are related to the research article entitled “Hybrid coagulation-UF processes for spent filter backwash water treatment: a comparison studies for PAFCl and FeCl3 as a pre-treatment” (Ebrahimi et al., 2017) [1]. This article reports the cost estimation for treating produced spent filter backwash water (SFBW) during water treatment in Isfahan- Iran by various methods including primary sedimentation, coagulation & flocculation, second clarification, ultra filtration (UF) and recirculation of settled SFBW to water treatment plant (WTP) entrance. Coagulation conducted by PAFCl and FeCl3 as pre polymerized and traditional coagulants. Cost estimation showed that contrary to expectations, the recirculation of settled SFBW to WTP entrance is more expensive than other method and it costs about $ 37,814,817.6. Versus the cheapest option related to separate primary sedimentation, coagulation & flocculation in WTP. This option cost about $ 4,757,200 and $ 950,213 when FeCl3 and PAFCl used as coagulant, respectively.

Data accessibility Some data are within this article and some presented in published article. Of course published data was presented in this article but with reference number and citation.

Value of the data
The data presents the suitable method among recirculation of settled SFBW to WTP entrance, coagulation & flocculation, and ultra filtration process for SPBW treatment Cost estimation for SFBW reuse by mentioned methods at full scale. Effect of cost estimation on process selection and Vice versa.

Data
The dataset of this article provides information on the cost estimation of SFBW treatment by various methods, including recirculation of settled SFBW to WTP entrance, coagulation & flocculation, and ultra filtration process. Coagulation conducted with two different coagulant including PAFCl and FeCl 3 . Tables 1, 2 and 3 show the amount of coagulants consumption (according to optimum dose of coagulants) and cost estimation for all process that used for SFBW treatment at full scale (Q ¼24,000 m 3 /d). Also all dimension, instrument, chemical matter and required parameters for water treatment plant were estimated and used for estimation.

Quantity of raw SFBW
Coagulation, flocculation, sedimentation and rapid sand filtration processes are main section of Isfahan water treatment plant that treats 12 m 3 /s of water. There are 48 filter units in this plant and PACl used as coagulant. During backwashing of each filter, some 500 m 3 of wastewater was generated. Considering 48 filter with 24 h cleaning interval it accounts for about 2.25% of the raw water entering to the plant. So, during water treatment process approximately 24,000 m 3 /d of SFBW is generated.

Experimental procedure
In our previous study, continues processes including primary sedimentation, coagulation, flocculation, secondary sedimentation and UF were used for the SFBW treatment. Inflow of all sections of the pilot except UF membrane was 10 l/h. Hydraulic retention time (HRT) for mentioning sections, except UF membrane was 60, 6, 48 and 192 min. Optimum pH for coagulation with PAFCl and FeCl 3 was 8.3. Also, optimum doses of PAFCl and FeCl 3 were 10 mg/L and 30 mg/L for spring and summer and 15 mg/L and 40 mg/L for autumn and winter seasons. Mixing speed at rapid mixer basin was 80 rpm. Mixing speed at flocculation tanks was 48 rpm. The UF module was operated in a dead-end mode with constant filtration about 8 L m −2 h -1 at a trans-membrane pressure of 300 Pa. It was operated in a cycle of 60 min filtration and 1 min backwashing with permeate in the reverse direction. At the end the recirculation of settled SFBW to WTP entrance and mixing with raw water was investigated according to its effects on coagulation usage at WTP in full scale situation [1][2][3][4]. All dimensions for full scale treatment were designed and by considering civil construction materials, chemical consumption, equipments and other important parameters cost estimation was done.
The importance of proper treatment processes for SFBW is that in case there are some concentrations of pollutants being accumulated in the SFBW they will be removed to much lower concentrations with lower costs than advanced water treatment processes [5][6][7].