Efficiency Of Micro-Nanobubbles for Wastewater Treatment in Puerto Bermúdez , Oxapampa , Pasco

En nuestro país, los vertimientos de aguas servidas afectan los cuerpos de agua, a la salud pública y como también a los diferentes ecosistemas sin tener ningún tipo de tratamiento. Por ello se planteó un tratamiento diferente y eficaz para la minimización de los coliformes totales presentes en los efluentes de Puerto Bermúdez, Oxapampa, Perú con la generación de micro-nanoburbujas de aire. Se determinó el grado de contaminación mostrada en los diferentes parámetros ya sean físico-químicos y también biológicos; así como su minimización en los impactos para obtener un mejor calidad de vida. La investigación fue experimental, se hizo el armado del generador de micro-nanoburbujas de aire para la realización del tratamiento por dosificación. Se realizaron los análisis respectivos para determinar el grado de contaminación y así tratarlas con micro-nanoburbujas en diferentes cantidades y para tener el mejor resultado. Los resultados del tratamiento con micro-nanoburbujas de aire fueron favorables. Se logró una eficiencia de 66.21%.


Introduction
The WHO (2015) estimates an approximate 842 000 inhabitants worldwide die annually from the disease of diarrhea.This is a result of the unhealthiness of these waters, a lack of sanitation as the lack of poor hygiene in the hands.However, this disease is preventable if the competent authorities and entities take corrective measures in the health and hygiene necessary, with the commitment of the population preventing the deaths of 361 000 children less than five years of age annually.
The problem now exists in populated centers of the regions of Peru as Bermudez Port, Oxapampa, Peru, and their sewage is discharged directly to the channels and streams that run around the populated center; causing contamination to water bodies, their biodiversity and the health of the population and thus giving as an alternative of decontamination using the technique of Micro-Nanobubbles (MNBs) for their disinfection.
The environmental nanotechnology is a technological discipline which study properties of natural and manmade nanomaterials, applications, techniques for their characterization, integration processes and transformation into ecosystems (Valverde, 2016).Microbubbles have the ability to change the normal characteristic of water (Tsuge, 2014).The Microbubbles (MBs) have diameter more than 100 μm, the micronanobubbles (MNBs) have diameter between 1 to 100 μm and the nanobubbles (NBs) have diameter less than 1 μm within the fluid field (Valverde, 2016).Microbubbles (MBs) possess special properties such as the capacity for generating free radicals (Sadatomi et al., 2007), self-pressurization, and carrying a negative charge.Such properties have attracted much attention in the fields of food science and agriculture (Takahashi and others 2007a).MNBs have now attracted attention for applications in engineering areas such as the sewage treatment of wastewater by air flotation (Choung et al 1993, Fan et al. 2010).Ozone (O3) is a strong oxidizing agent commonly used for sterilization, virus inactivation, deodorization, bleaching (decoloration), and decomposition of organic matter (Takahashi and others 2007a).Thermotolerant coliforms using air-ozone nanobubbles decreased from 1400 NMP / 100mL to 56 NMP / 100mL, achieving an efficiency of 96%, (BVSDE, 2006;Abate and Valverde, 2017).Air-ozone micronanobubbles can reduce coliforms in domestic residual water (Cruz & Valverde, 2016).
The micro-bubble generation technology in water is applied in Health, especially when person has cardiovascular problems (Valverde, 2016).

i) Collection of marine water sample
The wastewater samples were collected, following the indications of the Quality Monitoring National Protocol of Water from Peru.

ii) Sample analysis in laboratory
The total coliforms were analyzed by an accredited laboratory.Also field parameters as Temperature, pH, Turbidity, Electrical Conductivity, BOD5, COD, Dissolved Oxygen, and Total coliforms were measured.

iii) Fabrication of air-ozone micro-nanobubbles (MNBs)
The research was carried out ex-situ, in laboratory, where the whole system was first assembled to generate and to use the air micro-nanobubbles in wastewater.The patent obtained by Dr. Eng.Jhonny Valverde Flores was used to generate air MNBs.The schematic diagram of experimental apparatus for preparation of MNBs solutions is shown in Figure 1.The obtained average diameter of a MNB was 7 μm, the water flow was 4.67 L/s, the gas pressure was 90 PSI.

v) Treatment's efficiency in laboratory
Results of the three samples in different concentrations were analyzed after of using air micro-nanobubbles.
To measure the MNBs treatment's efficiency on total coliforms (TC) was used the equation 1:

Treatment of Samples
Samples of Physico-Chemical parameters from wastewater with total coliforms before and after of treatment.The physic-Chemical parameters measured were: temperature, pH, Turbidity, and electrical conductivity.The temperature in S2 (26.9 ºC) was a little higher than temperatures of S1 (26.5 ºC) and S3 (26.3 ºC).The turbidity in S1 (49.4 NTU) was lower than the initial turbidity (199 NTU).The electrical conductivity in S1 was higher (850 μS/cm) than the initial electrical conductivity in (32 μS/cm).See Table 1.The Biological parameters measured were: Biological Oxygen Demand (BOD), Chemical Oxygen Demand (COD), and Dissolved Oxygen (DO).The Biological Oxygen Demand (BOD) in S1 and S2 (4 mg/L both of them) was lower than the initial Biological Oxygen Demand (10 mg/L).The Chemical Oxygen Demand (COD) in S1 (8 mg/L) was lower than the initial Chemical Oxygen Demand (23 mg/L).The Dissolved Oxygen (DO) in S1 (8.64 mg/L) was higher than the initial Dissolved Oxygen (DO). in (7.27 mg/L).See Table 2.The total coliforms in S1 (4900 CFU/100mL) was lower than the initial total coliforms (14500 CFU/100mL).se Table 3.

Figure 2 .
Figure 2. Average diameter of a MNB size is 7 μm iv) Treatment of the sample Four samples (One initial sample and three samples after treatment) were dosed in order to evaluate the best reduction of total coliforms into the wastewater.Sample 1 is called S1 [300 mL (wastewater) + 700