WasteWater Treatment Lagoons

Treatment Lagoons can be considered as a good replacement for sand drying beds system to remove water from digested sludge coming from wastewater plant processes. However, the limitation on lagoons is that, it is not suitable for use in dewatering limed, untreated sludge because the process will emit strong odor causing a nuisance. Evaporation is the main mechanism for removal of water and the effectiveness of the lagoons, can be attributed by different factors such as climate change, in which cold condition can limit and slow down dewatering process.

Lagoons are best setup and constructed in dry and hot areas whereby high temperature will help to increase the evaporation rates. Construction of lagoons must be accompanied with proper drainage so that this will not cause environmental pollutions especially on groundwater supply. This is even stricter especially on places close to water catchment areas. Usually digested sludge is pumped to the lagoon at high rate so that when it enters the system, it will be evenly distributed all over without stagnant pockets. The collected sludge solid is removed mechanically using a sludge dryer and achieving solid content of between 25 to 30 percents while the liquid wastewater can be recycled back to the lagoon for further treatment to evaporate off further.

Different lagoons can have varying cycle times with some ranging from several months up to years. There is also a requirement whereby a sufficient space must be left in between each lagoon so that this will allow routine tasks such as cleaning and maintenance work to be carried out easily. The design of the lagoons must be at least 6 feet in depth depending on the digested sludge feed rate and final treatment capacity and generally, all the other processes must be synchronized along to get the best wastewater treatment lagoon setup.

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