Organic matter, nutrients, and optical characteristics of sewage lagoon effluents
作者:
R. J. Davies‐Colley,
C. W. Hickey,
J. M. Quinn,
期刊:
New Zealand Journal of Marine and Freshwater Research
(Taylor Available online 1995)
卷期:
Volume 29,
issue 2
页码: 235-250
ISSN:0028-8330
年代: 1995
DOI:10.1080/00288330.1995.9516657
出版商: Taylor & Francis Group
关键词: algae;domestic sewage;lagoons;nutrients;optical properties;oxidation ponds;oxygen demand;wastewater;water quality
数据来源: Taylor
摘要:
The effluent characteristics of 11 domestic sewage waste stabilisation lagoons designed to national specifications were examined, with emphasis on their optical properties, biochemically active constituents, and receiving water impacts. Measurements of 26 variables were analysed and compared with our previous (1989) survey of lagoon effluent quality in New Zealand. There was considerable variation in effluent composition of the lagoons, although seasonality was not marked (< 3‐fold change between summer and winter). The filterable proportion of total BOD5 appeared to be a useful indicator of lagoon performance. Nutrient levels in lagoon waters were high (overall medians were 5.1 g m−3for dissolved reactive phosphorus and 10.5 g m−3for dissolved inorganic nitrogen). The concentration of ammoniacal‐N, which comprised most of the dissolved inorganic nitrogen, was highly variable (ratio of 95 to 5 percentile = 1900); this is of concern as a toxicant both to algae within lagoons and to aquatic life in receiving streams. Aquatic humus and algal biomass both contribute to the restricted light penetration (median euphotic depth‐0.35 m) into lagoon waters (typically 1.2 m depth), apparently resulting in frequent light limitation of algal photosynthesis. Pond effluent character seems to be influenced strongly by sunlight and wind, via their effects on lagoon solids (largely algal biomass and associated detritus). Dilution of lagoon effluents by 40‐fold would ensure that receiving streams meet existing guidelines for most attributes of concern, but > 100‐fold dilution may be required to prevent visual clarity impacts, and several hundred‐fold dilution to prevent benthic algal proliferations.
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