the photosynthetic activities of pond algae, there is a diurnal
variation in the dissolved oxygen concentration. The dissolved
oxygen concentration in the water gradually rises after sunrise,
in response to photosynthetic activity, to a maximum level in
the mid-afternoon, after which it falls to a minimum during
the night, when photosynthesis ceases and respiratory activities
consume oxygen. At peak algal activity, carbonate and bicarbonate
ions react to provide more carbon dioxide for the algae,
leaving an excess of hydroxyl ions. As a result, the pH of the
water can rise to above 9, which can kill faecal coliform. Good
water mixing, which is usually facilitated by wind within the
upper water layer, ensures a uniform distribution of BOD, dissolved
oxygen, bacteria and algae, thereby leading to a better
degree of waste stabilization.
12.5.1.3. Maturation ponds. The maturation ponds, usually
1–1.5 m deep, receive the effluent from the facultative ponds.
Their primary function is to remove excreted pathogens.
Although maturation ponds achieve only a small degree of
BOD removal, their contribution to nutrient removal also
can be significant. Maturation ponds usually show less vertical
biological and physicochemical stratification, and are welloxygenated
throughout the day. The algal population in maturation
ponds is much more diverse than that of the facultative
ponds, with non-motile genera tending to be more common.
The algal diversity generally increases from pond to pond
along the series (Mara, 1989). Although faecal bacteria are
partially removed in the facultative ponds, the size and numbers
of the maturation ponds especially determine the numbers
of faecal bacteria in the final effluent. There is some removal of
solids-associated bacteria in anaerobic ponds, principally by
sedimentation. The principal mechanisms for faecal bacterial
removal in facultative and maturation ponds are now known
the photosynthetic activities of pond algae, there is a diurnalvariation in the dissolved oxygen concentration. The dissolvedoxygen concentration in the water gradually rises after sunrise,in response to photosynthetic activity, to a maximum level inthe mid-afternoon, after which it falls to a minimum duringthe night, when photosynthesis ceases and respiratory activitiesconsume oxygen. At peak algal activity, carbonate and bicarbonateions react to provide more carbon dioxide for the algae,leaving an excess of hydroxyl ions. As a result, the pH of thewater can rise to above 9, which can kill faecal coliform. Goodwater mixing, which is usually facilitated by wind within theupper water layer, ensures a uniform distribution of BOD, dissolvedoxygen, bacteria and algae, thereby leading to a betterdegree of waste stabilization.12.5.1.3. Maturation ponds. The maturation ponds, usually1–1.5 m deep, receive the effluent from the facultative ponds.Their primary function is to remove excreted pathogens.Although maturation ponds achieve only a small degree ofBOD removal, their contribution to nutrient removal alsocan be significant. Maturation ponds usually show less verticalbiological and physicochemical stratification, and are welloxygenatedthroughout the day. The algal population in maturationponds is much more diverse than that of the facultativeponds, with non-motile genera tending to be more common.ความหลากหลายของสาหร่ายโดยทั่วไปเพิ่มขึ้นจากบ่อบ่อตามลำดับ (มาร 1989) แม้ว่าแบคทีเรีย faecalเอาบางส่วนในบ่อ facultative ขนาด และตัวเลขเจริญเติบโตของ บ่อโดยเฉพาะกำหนดหมายเลขของแบคทีเรีย faecal ในน้ำสุดท้าย มีบางกำจัดแบคทีเรียที่เกี่ยวข้องของแข็งในบ่อที่ไม่ใช้ออกซิเจน หลักโดยตกตะกอน กลไกหลักสำหรับแบคทีเรีย faecalใน facultative และบ่อเจริญเติบโตเป็นที่รู้จักกันตอนนี้
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