Choosing Aquatic Plant Species for High Wastewater Treatment Efficiency through Small Wetland

The research was aimed to choose the most appropriate aquatic plant in high capacity as grown in small wetland for community wastewater treatment, they were Typha angustifolia Linn., Cyperus corymbosus Rottb., and Canna indica Linn. The small wetland, sometimes called vertical flow constructed wetland (VFCW), has been designated on 100-m long, 5-m wide and 0.75-m deep in size in which four-hole pipes were laid down at the bottom for releasing some treated wastewater as effluent through the outlet to the storage reservoir. There must be paved the gravel on the bottom up to the level of 5-cm height and overtopping with sand about 15 cm that be followed by 30-cm mixed soil (soil: sand equivalent to 3:1). All selected aquatic plant species were planted in small wetland before flowing community wastewater until soil at saturated level for first week and about 30 cm during second week up to the maximum age of plants. The choosing aquatic plant species were only depended on the high efficiency of wastewater treatment. The most probable aquatic plant was selected on Typha as the first priority for high wastewater treatment efficiency, Canna the second, and more or less efficiency for the others. Fortunately, Typha has been grown well in everywhere, particularly flat wetland in central, west, east and down north of Thailand.


Introduction
Thailand had been facing the stream pollution since 1970.H.M. the King Bhumibol has realized the worsen water pollution of the country and studied the possibility on how to recover with nature-by-nature process for longer period of time before starting-up.The King's Royally Initiated Laem Phak Research and Development Project (The Royal LERD Project) has been established in the year of 1990 at Laem Phak Bia Sub-District, Ban Laem District, Phetchaburi Province, the central of Thailand.The nature-by-nature process which is extremely necessary for bacterial organic digestion processes in the tropical latitudes like Thailand as pertained to solar radiation, promising plant species, ecological niche of microorganism for organic digestion processes and plenty of organic matters as pointed out by Metcalf and Eddy (1979); Ye et al. (2001); Yang et al. (2008); Keddy (2010); Penha-Lopes et al. (2012).Actually, wetland is occurred between the terrestrial and aquatic systems in order to absorb the toxic contaminants by humus, organic matters and soils before draining away to stream or river.
Constructed wetland are becoming popular worldwide for removing contaminants from wastewater that are low-cost, easy to operate, and require less maintenance than other wastewater treatment technologies.Constructed wetland have appropriate to treat contaminants from wastewater in developing countries.Aquatic plants are main component of a constructed wetland system.They play important roles in degrading and removing nutrients and other pollutants (Cui et al., 2010).Aquatic plant has eventually to remove contaminants from wastewater and soils as growing units through root system under the osmotic pressure during the photosynthesis processing, then the elements are translocated to accumulate in all parts of vegetative organ, but it depends on the degree of toxic chemical contaminants and aquatic plant species (Tateuyama et al., 1967;Reddy et al., 1990;Rai et al., 1994;De Souza et al., 1999;Marin and Ayele, 2003;Pulford and Watson, 2003;Xia and Ma, 2006;Gupta and Sinha, 2007;Wahla et al., 2008;Thaipichitburapa et al., 2010;Zaier et al., 2010;Chunkao et al., 2012) www.ccsenHowever, efficiency

Water
The basic wastewater demand (B above have Marin and (2012).

Rhizob
The aquati flowering s techniques

Growth
Accordanc stagnated w experimen Linn.) gre constructed 105 days fo  and Leto et al. (2013) reported that the root growth of Canna with fibril roots was faster than Typha and Cyperus with rhizomatic roots due to fibril roots had higher root number than rhizomatic roots but rhizomatic roots showed a longer root lifespan than those with fibril roots.However, root biomass between the plants with rhizomatic roots and those with fibril roots were not significant.The ratio of shoot biomass to root biomass of Canna and Typha were about 2.94 and 3.10, respectively, which revealed that Canna had belowground yield greater than aboveground but Typha had aboveground yield greater than belowground.In addition, Typha colonized a larger surface area and produced significantly higher yields of aboveground and belowground biomass than Cyperus.Some previous studies reported that Typha in constructed wetlands for peatland restoration showed high biomass production because of the peatland as a sink in the nutrient cycle may be reactivated (Wild et al., 2001) and Canna can grew every well in constructed wetland condition (Konnerup et al., 2009).In the other hands, Typha biomass was probably less than Cyperus in stress condition as lack of water due to Typha needed very high water demand and also limited capacity to close stomata and reduce water loss by transpiration, but Cyperus also survived in drier sites that showed a higher capacity to tolerance water stress (Kantawanichkul et al., 2009).

Influences of Plant Species on Water Quality
After analysis of filtrated wastewater samples of those 9 main plots, the results found the averaged values as shown in Table 2.The BOD removal efficiencies of Typha angustifolia Linn., Cyperus corymbosus Rottb., and Canna indica Linn., were 88.47%, 82.16% , and 86.62%, respectively.The concentration of BOD were removed by Typha greater than Cyperus and Canna.For making clear understanding the function of the vertical flow on aquatic plant filtration plots under the concept of constructed wetland, the water quality indicators was taken an account with BOD as the representative.In principles, the organic matter has to be digested by aerobic and anaerobic processes at the top-layer wastewater and the middle-layer soil growing media during vertical flow into the bottom of constructed wetlands.
The results were related to Leto et al. (2013) who reported that Typha had a good level of BOD removal efficiency (72.4%) and higher BOD removal efficiency than Cyperus (64.8%), and Abou-Elela and Hellal (2012) reported that average BOD removal efficiency were 92% for Canna, Phragmites, and Cyperus with vertical flow constructed wetland(VFCW).The quality of treated effluent proved that the use of VFCW as a treatment step was an efficiency technology for small community wastewater treatment.The high removal efficiency of BOD was rapidly removed by deposition and filtration, while organic compounds were degraded both aerobic and anaerobically by the heterotrophic microorganism depending on oxygen concentration in the system.
Total suspended solid (TSS) removal efficiency of Cyperus (58.77%) was higher than Typha (48.47%), and Canna, (47.91%), respectively, while the efficiency of total nitrogen and total phosphorus removal were not significantly different among species.Although many reports demonstrated that Canna was high nutrient removal efficiency due to Canna were high growth rate (Konnerup et al., 2009) and Typha were plants that were able to establish successfully for high concentration of nutrient in wastewater treatment system (Calheiros et al., 2007), but differences in the removal of nitrate and BOD among plant species were due to differences in chlorophyll fluorescence, a photosynthetic characteristics, leading to different root lengths and total root biomass.Oxygen release to rhizosphere by wetland plant was directly governed by total root biomass and significantly influences the removal of ammonia and total dissolved phosphorus and chemical oxygen demand resulted from the filtration by root system.Nutrient uptake capacity was likely related to habitat preference and influenced by the structure of roots and rhizome.However, non-species-specific significant positive correlation was found between root oxygen release, root porosity, and radial oxygen loss rates were also positively correlated with plant tolerance to domestic wastewater and removal of total nitrogen and total phosphorus, hence nutrient removal might be not significantly different among species (Zhang et al., 2009;Li et al., 2013;Mei et al., 2014).Furthermore, the chosen species of aquatic plants were more efficient for the removal of pollutants in the long term.The different of pollutant removal efficiency among aquatic plant species were more not extremely great, especially in short period.The effect of aging on main parameters involved in pollutant removal in small constructed wetland such as temperature, pH, conductivity, dissolved oxygen concentration and redox potential (Hijosa-Valsero et al., 2012;Konnerup et al., 2009).

Influences of Rhizobacterium on Wastewater Treatment Efficiency
Typha angustifolia Linn., Cyperus corymbosus Rottb., and Canna indica Linn.were determined for the number of rhizobacterium in small constructed wetland system.Typha was found 8.27 x 10 6 CFU/g and 1.69 x 10 7 CFU/g in the first day and 71days of the experimental periods, respectively.Cyperus was found 6.49 x 10 6 CFU/g and 2.82 x 10 8 CFU/g in 57 days and very less in 71 days of the experimental period, respectively.The number of rhizobacterium in Canna was found about 3.97 x 10 6 CFU/g in the first day, 3.18 x 10 7 CFU/g in 43 days, and 1.37x10 7 CFU/g in 71 days of the experimental period, respectively (Table 3).The number of rhizobacterium were increased by period of plant growth, the highest number of rhizobacterium at the flowering stage, and decreased in the old stage because influences of exudates substrate from plant roots which were carbon and energy sources for bacteria growth (Sylvia et al., 1998;Gupta et al., 2000;Michael et al., 2000;Walker et al., 2003;Ibekwe & Grieve, 2004).The number of rhizobacterium in each stage of plant growth was significantly different at the level of 0.05.The report of Calheiros et al. (2009) showed that Bacillus sp. and Pseudomonas sp. were found in Typha latifolia in constructed wetland.The number of rhizobacterium affected to the efficiency of wastewater treatment, due to organic substrates from community wastewater, were also digested by most of these bacteria which were heterotrophic bacteria.Metabolic profiles of microbial community in wetland only depended on the presence of plants but did not depended on the plant functional group level.Diversity of microbial community all were not significantly affected by the plant functional group richness level, appearing that total shift in microbial community in the constructed wetland only depended on the presence of plant species.Increasing in plant species richness microbial biomass carbon and nitrogen and utilization of amino acids but limited the utilization of amine and amides (Zhang et al., 2010;Zhang et al., 2011).Furthermore, bacteria community change related to the type of substrate different hydraulic loading and constructed wetland operation.(Gupta et al., 2000;Misko & James, 2002;Dilfuza & Gisela, 2003;Janis et al., 2003)

Conclusion
The three aquatic plants were selected for 9-small experimental plots which were vertical-flow constructed wetland (VFCW).There were Typha angustifolia Linn., Cyperus corymbosus Rottb., and Canna indica Linn.All of plants were particular formed in tropical countries like as Thailand.The findings showed that the priority for plant selection depended on high efficiency of BOD removal, growth rate, biomass, and the number of rhizobacterium, which played important role to remove contaminants from wastewater.Typha was the first priority selection for small wetland domestic wastewater treatment system due to higher growth rate, biomass, and efficiency of BOD removal than other species.Although, the number of rhizobacterium of Typha was less than Cyperus and Canna, but the previous studies showed that microbial community were not significantly affected by the plant functional group richness level, drove the shift in microorganism for utility miscellaneous compound in constructed wetland system.Furthermore, Typha had been grown well, common occurred in everywhere, and cutting leaves of them could be made for handicrafts.Canna might be considered for small wetland domestic wastewater treatment system because of its flowers may be preferred in aesthetic condition.Hence, adaptability of a species to climatic conditions in order to ensure maximum results from the aquatic plants in wastewater treatment should be considered.
Figure 2 corymbosu . Many studies have Wenyin et al. (2007)atic plants were shown in Table1which indicated growth production of each plant.The total biomass (stems and rhizomes) after harvesting period, showed that wet weight and dry weight of Canna indica Linn.was greater than Typha angustifolia Linn.andCyperus corymbosus Rottb, respectively.Wenyin et al. (2007)

Table 2 .
Water quality indicators of vertical flow constructed wetland (VFCW) as collected at the inlet and outlet of constructed wetlands for community wastewater treatment in Phetchaburi province, Thailand

Table 3 .
The number of rhizobacterium in Typha angustifolia Linn., Cyperus corymbosus Rottb.and Canna indica Linn. in Constructed Wetland System for Phetchaburi Municipal Wastewater Treatment Isolation and identification of rhizobacterium were performed 73 isolate from root of three selected plants.Typha angustifolia Linn.was found 3 genus such as Bacillus sp., Enterobacter sp. and Flavobacterium sp.The 4 genus were found in Cyperus which were Bacillus sp., Pseudomonas sp., Micrococcus sp. and Aeromonas sp. and in Canna were found 5 genus as Bacillus sp., Xanthomonas sp., Corynebacterium sp., Azotobacter sp. and Pseudomonas sp.Bacillus sp were the most generally found in each species.Other bacteria species were found Arthrobacter sp., Pseudomonas sp., Azotobacter sp., Xanthomonas sp., Micrococcus sp., Corynebacterium sp. and Acinetobacter sp.