Abstract

H.M.The King’s initiative nature by nature process for community wastewater treatment has been conducted since 1990 at Laem Phak Bia sub district, Ban Laem district, Phetchaburi province, Thailand on UTM 1442240 to 1443480 N and 0619271 to 0619271 E. The fresh food markets and households were the point sources of Phetchaburi municipal wastewater that flowing newly construction sewage system in order to receive them to four sub stations on both sides of Phetchaburi river before pumping to Klongyang collection pond. The storage wastewater has been pumped about 3,600 cu.m./day through the 18.5 km. HPDE pipe and putting into sedimentation pond 1 and another four consecutive ponds (oxidation ponds 2, 3, 4, and 5) before the effluent flowing into the mangrove forest. However, the results of experiment found the values of BOD that showing drastic decreasing from Klongyang collection pond through the tip of 18.5 km. HPDE pipe to the sedimentation pond 1 then after it was gradually decreased from one oxidation pond to the next one. Highlight was placed on the obtained effluent after treated wastewater flowed over weir crest that finding BOD under standard and also the decreasing of total coliform bacteria and fecal coliform bacteria, particularly the pathogenic bacteria decreasing down to almost zero MPN/100mL. The question came up how total coliform bacteria and fecal coliform bacteria disappeared after the treated wastewater flowing over weir crest of the oxidation pond 3. The hypothesis was set on the effect of solar radiation to DO and H₂O₂ which were employed for bacterial organic digestion process in wastewater treatment ponds by taking the measurement randomly on 19 May 2011 that solar radiation showing the solar energy between 0-750 W/m² all together with UV-A, UV-B, spectrum and net radiation.

In order to accomplish the objectives of study, the wastewater quality indicators were found BOD in sedimentation pond 1 67.5 mg/L and oxidation pond 3 16.6 mg/L for 13 hours measurement. In the same manner, the values of DO and H₂O₂ for 13 hours measurement found in oxidation pond 3 greater than sedimentation pond 1 in respect to 8.9 and 7.6 mg/L for DO and 2.27 and 0.31 µg/L for H₂O₂. Moreover, the polynomial correlation was studied in order to determine the relationship between net radiation and DO and found very high correlation coefficients in both sedimentation pond 1 and oxidation pond 3. For the quantity of H₂O₂, it was obtained the relationship between net radiation and H₂O₂ in higher correlation coefficient in sedimentation pond 1 than oxidation pond 3 because of smaller amount of dissolved organic and inorganic matters in oxidation pond 3. It would be the reason that oxygen which occurred from phytoplankton and algae photosynthesis were not employed by organic digestion and respiration of bacteria. Therefore, it had to exist DO and accumulation only in water instead of producing H₂O₂ in oxidation pond 3 during daylight time. This is why H₂O₂ in oxidation pond 3 was not varied directly to net radiation, and also causing an indication on the relationship between net radiation and H₂O₂ in oxidation pond 3 lower than sedimentation pond 1. Summarily speaking, the nature of solar radiation plays vital role in encouraging producing DO and H₂O₂ which are the important factors in bacterial organic digestion for community wastewater treatment with high efficiency.

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