Review on mechanisms and efficiency of removal of microbiological contaminants in constructed wetlands

• Autorzy: Łuczkiewicz, A. , Kulbat, E. , Olańczuk-Neyman, K. , Quant, B. , Rymszewicz, A.

Warianty tytułu

PL

Mechanizmy i efektywność usuwania zanieczyszczeń mikrobiologicznych na filtrach gruntowo-roślinnych

• Języki publikacji: EN

Abstrakty

EN

Constructed wetlands (CW) have been considered as a waste and a stormwater treatment systems for small communities or for areas with unsteady sewage flow conditions. Several investigations were undertaken for estimation suspended solids, organic matter and nutrients efficiency removal but only few focused on retention of microorganisms in constructed wetlands. In this review mechanisms of elimination of viruses, indicator bacteria as well as helminth eggs and protozoan parasites are discussed. Generally the retention and the removal efficiency of microorganisms in the wetlands systems can be attributed to the combination of filtration, sorption and inactivation, which are controlled by the retention time and the flow condition. Filtration depends on the beds' matrix and involves the physical blocking of movement through the pores smaller than microorganisms. Binding between the solid surfaces and the microorganisms (especially bacteria cells) is mainly affected by the chemistry of the bed particles and the properties of the microbial organisms. The rate of microorganisms inactivation is probably also influenced by abiotic and biotic factors. The majority of allochtonic microorganisms die off after introduction to the "natural" treatment systems such as wetlands because of the abiotic stress. But even subpopulations better suited for survival and colonization, can also be eliminated because of predation. The bacterial phages, protozoa and nematodes as well as inhibitory substances secreted by other bacteria may also be a reason of reduction of the enteric bacteria in the wetland conditions. Also macrophytes in the wetland system are regarded as an essential in hygienisation of wastewater. However bacterial elimination in constructed wetlands is regarded as a highly efficient (> 99.9%), the final number of bacteria in the treated sewage can still affect the environmental ecosystems.

PL

Hydrofitowa metoda jest stosowana do oczyszczania wód opadowych, ścieków bytowo-gospodarczych z pojedynczych gospodarstw oraz odcieków ze składowisk komunalnych. Większość publikowanych wyników badań dotyczących skuteczności oczyszczania ścieków na złożach gruntowo-roślinnych koncentruje się głównie na zagadnieniach usuwania zawiesiny, substancji organicznych i pierwiastków biogennych, natomiast nieliczne tylko prace prezentują wyniki stanu sanitarnego odpływów. W pracy scharakteryzowano zasadnicze mechanizmy przyczyniające się do usuwania zanieczyszczeń mikrobiologicznych ze ścieków oczyszczanych w różnych konfiguracjach systemów hydrofitowych oraz przedstawiono ich efektywność w eliminacji bakterii wskaźnikowych. Obniżanie liczby bakterii pochodzenia kałowego, cyst pierwotniaków i jaj helmintów w procesach oczyszczania ścieków na filtrach gruntowo-roślinnych jest efektem ich zatrzymywania, eliminacji oraz obumierania. Zatrzymywanie tego typu allochtonicznych zanieczyszczeń w ośrodku porowatym jest efektem fizykochemicznych procesów, takich jak: sedymentacja, filtracja i adsorpcja, na które wpływają warunki przepływu i czas zatrzymania. Do obniżania liczby mikroorganizmów (eliminacji) przyczyniają się biologiczne procesy, wśród których do najważniejszych należą: drapieżnictwo, antagonizm, konkurencja o substancje pokarmowe lub pierwiastki śladowe i liza przy udziale bakterii lub wirusów. Obumieranie jest natomiast skutkiem niekorzystnego wpływu różnorodnych czynników abiotycznych, takich jak: odczyn (pH), temperatura, działanie promieniowania UV, brak wilgoci. Ponadto istotną rolę w usuwaniu zanieczyszczeń mikrobiologicznych odgrywają makrofity porastające systemy hydrofitowe, których skuteczność jest w znacznym stopniu związana z porą roku. Makrofity zmniejszają przepływ ścieków i sprzyjają sedymentacji drobnych cząstek zawiesiny wraz z zatrzymanymi na nich bakteriami. Również liczne substancje produkowane przez ich system korzeniowy względnie produkowane przez populacje bakterii zasiedlające korzenie są toksyczne dla bakterii pochodzenia kałowego. Z drugiej zaś strony makrofity chronią mikroorganizmy przed szkodliwym wpływem promieniowania UV. Wprawdzie skuteczność usuwania bakterii wskaźnikowych na filtrach gruntowo-roślinnych jest zbliżona do uzyskiwanej w wysoko efektywnych oczyszczalniach ścieków, to jednak odpływy z obu typów oczyszczalni nadal budzą zastrzeżenia pod względem mikrobiologicznym.

Słowa kluczowe

PL

ścieki; filtry gruntowo-roślinne; mikroorganizmy; usuwanie zanieczyszczeń mikrobiologicznych

EN

wastewater; constructed wetlands; microorganisms; microbiological contaminants removal

• Czasopismo: Inżynieria i Ochrona Środowiska
• Rocznik: 2006
• Tom: T. 9, nr 4
• Strony: 349-363
• Opis fizyczny: Bibliogr. 88 poz.

Twórcy

autor

Łuczkiewicz, A.

autor

Kulbat, E.

autor

Olańczuk-Neyman, K.

autor

Quant, B.

autor

Rymszewicz, A.

• Gdańsk University of Technology, Faculty of Civil and Environmental Engineering, ul. G. Narutowicza 11/12, 80-952 Gdańsk

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