Bioremediation for water purification – A case study at St. Coombs Lake, Talawakelle

Phytoremediation is one of the most eco friendly and innovative techniques to remove pollutants from soil and water in agricultural areas. This study explored potentials of bioremediation for water purification at Tea Research Institute of Sri Lanka through monitoring water quality of St. Coombs lake and through several glasshouse and laboratory experiments for validating the results during the period of November 2004- February of 2005.

The water quality parameters such as pH, nitrate, phosphate, iron and total coliforms at 35 0C / 100 ml and Escherichia coli at 440 C / 100 ml were monitored during dry and rainy periods. The possible causes for water pollution of the lake were also monitored. Nitrate pollution was greater during rainy periods since higher contribution of erosion and runoff. Higher levels of total coliforms and Escherichia coli were observed in both seasons. Five plant species traditionally known to have phytoremedial properties i.e. Kang kong (Ipomea aquatica), Giant reed (Arundo donax), Water hyacinth (Eichhornia cracipes), Bulrush (Scirpus lacustris) and Kumbuk (Terminalia arjuna) were evaluated for nutrient absorption. The histology of Kumbuk and Tea roots were assessed for their anatomical attributes to the bioremediation properties.

The differences in root anatomical traits in different plant species lead to differences in nutrient and water absorption. Kang kong, Water hyacinth and Bulrush showed better performances in nutrient absorption. The results supported the potentials and technical attributes to common bioremediation plant species in purification of water. These attempts would be environmentally and user friendly, cost effective as well as aesthetic advantages and long-term applicability compared to chemical treatments.

P G D S Amarasena1, K M Mohotti2 and G Hitinayake1
Department of Crop Science, University of Peradeniya, Sri Lanka
Tea Reserch Institue of Sri Lanka, Sri Lanka

Effects of some water quality parameters and some metals on osmoregulation of Oreochromis mossambicus in Bolgoda lake

The present study was carried out in Bolgoda Lake at Attidiya, Borupona and Dampe from September 2005 to January 2006 with the objective of studying the effect of some water quality & some heavy metals on Osmoregulation of Oreochromis mossambicus. Only the Dissolved Oxygen and Transparency showed significant difference among measured water quality parameter within 3 sites. The highest value of Dissolved Oxygen (9.40 ± 1.56 mg/l) was recorded at Attidiya & lowest from Borupona (3.88 ± 1.1 mg/l). Dissolved Oxygen of Dampe was 6.44 ± 2.20 mg/l. Osmoregulatory Capacity of three sites were significantly different. Maximum Osmoregulatory Capacity (240.90 ± 2.01) was recorded in Borupona and minimum Osmoregulatory Capacity (126.30 ± 1.12) was recorded in Dampe station. Osmoregulatory Capacity of Attidiya was 168.70 ± 0.79. A significant negative correlation of Dissolved Oxygen was recorded with Osmoregulatory Capacity. Transparency also made great effect to the Osmoregulatory Capacity. Maximum Osmoregulatory Capacity value was recorded in Borupona that has high transparency (87 ± 1.1 cm) and with low Transparency (65 ± 0.71cm) minimum Osmoregulatory Capacity value was recorded. That was in Dampe station. Transparency of Attidiya was 80 ± 0.79 cm.

There was a significant difference (P<0.05) in the metal levels in a particular organs (gills, muscles) and between the three sites. Gills recorded highest values for all measured metals in three sites. Most abundant metal in three sites was Fe. The Highest value was recorded in Attidiya (2940 ± 27.3µg/g). The lowest Fe value was recorded in Borupona (1290 ± 31.5 µg/g). Next most abundant metal was Zn. The highest value of Zn (805 ± 7.43µg/g) was recorded in Dampe and lowest value was recorded in Borupona (382 ± 3.59µg/g). Cu was found only in Attidiya site, but it was very low, relative to the other elements. A significant negative correlation with Osmoregulatory Capacity was observed for Zn in gills & muscles.

K W M Irodanie and A G D H Senevitathne
Department of Zoology, University of Sri Jayewardenepura, Sri Lanka.

Status of heavy metal pollution in the Lunawa lagoon

Distribution of five types of heavy metals in the Lunawa Lagoon (Colombo District) was investigated from April to June 2006. Water and bottom sludge samples were obtained at fortnight intervals from nine sampling stations of the lagoon including three drains (Northern, Eastern and Uyana). Water samples were preserved by adding Conc. HNO3 (Analytical Grade) to adjust the pH to < 2 and bottom sludge samples were treated by ‘Wet Ashing Method’ before analysis. Concentrations of Cu,Zn, Pb, Cd and Cr were determined by Atomic Absorption Spectrophotometry. Cu, Zn, Pb and Cr were found both in water and bottom sludge samples of all sites, while Cd was not recorded from any of the sites. Significantly higher concentrations of heavy metals (Mean ± SEM: Cu 120.75 µg/g ± 8.43; Zn 570.98 µg/g ± 11.53; Pb 204.37 µg/g ± 7.50; Cr 52.50 µg/g ± 4.36: One- way ANOVA; P<0.01) were found in bottom sludge of the Southern lagoon than the Northern lagoon and the three drains. This is possible because the Southern lagoon is situated away from the sea outfall and the intensity of flushing by sea water is relatively less in this sector. Heavy metal concentrations in water in different sites did not differ significantly, however, water in the Southern lagoon contained a relatively higher concentrations of Cu (0.049 ppm ± 0.002) and Pb (0.096 ppm ± 0.006) while the highest level of Cr (0.035 ppm ± 0.020) and Zn (0.151 ppm ± 0.017) were recorded from the Eastern Drain. Bottom sludge contained significantly higher concentrations of all heavy metals than in water (P<0.001) indicating accumulation of metal ions in the sludge for a long period of time. Lagoon water could have been contaminated by point sources (such as Automotive Workshops and Textile Factories) and nonpoint sources (such as Service Stations along the Galle Road) of heavy metal pollutants.

W R M N K Wickramasinghe1, P N Dayawansa1 and M D P de Costa2
1Department of Zoology, University of Colombo, Sri Lanka.
2Department of Chemistry, University of Colombo, Sri Lanka.

Colour removal and its mechanisms in textile wastewater treatment by UASB reactor system with anaerobic granular sludge

Textile wastewaters generated from different stages of textile processing contain various toxicants or pollutants that are seriously harmful to natural aquatic environment when released without proper treatment. Although there are different methods, which can be adopted for the treatment of textile wastewater, biological approaches are considered as environmentally friendly, low cost and effective methods over other physico-chemical methods. In the present study, simulated textile wastewater (STW) prepared by mixing of three popular acid dyes (Acid blue 204, Acid red 131 and Acid yellow 79) in synthetic wastewater was studied for the decolourization and removal of degradable organic in the laboratory scale Upflow Anaerobic Sludge Blanket Reactor system with anaerobic granular sludge for about five months at different organic and dye loading rates. The colour removal mechanisms under anaerobic treatment were also examined since microbial colour removal occurs basically in two ways namely biological degradation, which is more important in textile wastewater treatment, and adsorption of dye molecules onto microbial biomass. Chemical oxygen demand (COD) removal of acid red 131 (AR131) containing STW was about 80% at 300 mg/l dye concentration and it was over 89% in acid yellow 79 (AY79) dye containing STW under studied conditions. Although acid blue 204 (AB204) showed a little inhibition over methanogenic consortia, about 93% of COD removal was observed at 100 mg/l dye concentration. Colour removal of AR131 dye containing STW was 95% and it was credited to biodegradation. Treatment of STW prepared using AY79 showed 95% colour removal owing to biodegradation while AB204 was quite resistant to biodegradation by anaerobic microorganisms. Observed colour removal was merely due to the adsorption of dyes onto microbial granules. Even though a little accumulation of volatile fatty acid (VFA) was observed in increased dye concentrations, the detected values of VFA, alkalinity and pH showed that those values were in the range of desirable limits of anaerobic process. It seems that AR131 and AY79 can be decolourized almost completely by UASB reactor system while AB204 cannot be decolourised since all colour removal attributed to adsorption of dye onto microbial granules. It can be concluded that anaerobic technology can be used for the treatment of textile wastewater containing different dyes as an alternative method over other methods. However, further study of UASB reactor for the treatment of real textile wastewater is suggested to find out matrix effect of other chemicals present in real textile wastewater before application to the real world situations.

W Somasiri, Li Xiufen, Wenquan Ruan and Jian Chen
Laboratory of Environmental Biotechnology, School of Biotechnology, Southern Yangtze University, Wuxi,
Jiangsu, PR China.

Assessment of the impact of diuron to water bodies in the Walawa area

Use of pesticides has significantly increased global food production and it is indispensable in modern agriculture to control weeds, insects, other pests and diseases. As the population increases the use of pesticides also increases. The impact of these pesticides to the environment is not well understood for Sri Lankan conditions. Hence the sorption pattern of a non ionic pesticide, diuron {3-(3,4- dichlorophenyl)-1,1-dimethylurea; C9H10Cl2N2O} which is used as a herbicide to control weeds and mosses mainly in sugarcane, was studied for 14 soil series in the right bank of the Walawa basin in Sri Lanka.

Information was collected from farmers in Walawa areas on crops, historical cropping patterns, type of pesticides used, pesticides handling knowledge etc. The survey revealed that pesticides use is malpracticed by farmers. The distribution of crop types in the area during last three years shows that Paddy, which is scattered through out the area, is the most prominent crop. The average area under paddy cultivation is approximately 9800 ha. Banana was the second highest grown crop that is in about 4200 ha. Sugarcane, which covers about 2500 ha, is the prominent monoculture in the Walawa basin.

Adsorption of diuron to the collected surface (0-10cm) soils of the 14 soil series in the Walawa basin were measured using High Performance Liquid Chromatographic method. The Moraketiya series showed the highest sorption among them. It also gives the highest Kd value of the selected soils and Siyambala series exhibited the lowest adsorption and Kd. The organic carbon content was highest in Kachigalara series and it was lowest in the Walawa series. The measured Kd values were used to predict the risk of this pesticide to ground and surface water in the Walawa area using a simple management model called Pesticide Impact Rating Index, PIRI which resulted a moderate risk for the contamination of water bodies in the area.

 R C Watawala2, S Liyanage2, J A Liyanage1 and A P Mallawatantri
1Department of Chemistry, University of Kelaniya, Sri Lanka
2Department of Chemistry, University of Sri Jayewardenepura

Heavy metals in substrates of a freshwater wetland at Kelaniyas

Many natural wetlands function as successful remediation systems for the environmental impact due to industrial effluents and domestic effluents from urban and semi-urban areas. However, this protective function of natural wetlands often comes at the cost of substantial environmental degradation. Hence, wetland sediment analysis is essential in the assessment of the impact of industrial effluent discharge and in the determination processes of remediation of metals. The important fraction played by the sediments of wetlands is the regulation of nutrients (N, P, K) and other trace elements essential for plants as most bio-geo-chemical processes occur in the substrate of wetland to release nutrients and heavy metals.

Iriyawetiya wetland at Kelaniya is closer to the Kiribathgoda Township and it receives many effluents from urban runoff and industry. The urban runoff into wetland may include pollutants such as nutrients, toxic substances, poly-aromatic hydrocarbons, heavy metals, oils, pathogens and particles. A preliminary study showed that this wastewater carries appreciable amounts of toxic metals, especially heavy metals and their concentrations vary from place to place in the wetland. To determine the heavy metal concentrations in sediments of Iriyawetiya wetland, samples were collected from the inlets, outlets and the middle part of the wetland using a HDPE grab and metal concentrations in aciddigested samples were measured separately using an atomic absorption spectrophotometer.

Among the tested heavy metals Al, Fe, Cr, Zn, Cd, Mn and Ni (except Cu, Pb, Sn) were found in higher amounts in sediments at the inlet 01 area than the outlet area. Al, Cu, Sn, Cr, Zn, Cd, Pb, Mn and Ni in sediment of inlet 2 area were recorded comparatively lower values than the outlet area due to lesser loading of effluents in that area. The middle area of the wetland recorded higher amounts of all measured ten heavy metals than inlet 02. Al, Fe, Cu, Sn, Mn gave the highest values in the middle open areas of the wetland. This shows that pollutants in urban waste, when dispersed in to the aquatic environment, they accumulate primarily in water and sediments which accelerates the contamination of other water sources including groundwater and drinking water. Further it provides the mechanisms needed to be used for remediation methods of waste water using natural wetlands.

K G S Nirbadha1, J A Liyanage2 and M D Amarasinghe1
1 Department of Botany, University of Kelaniya, Sri Lanka.
2 Department of Chemistry, University of Kelaniya, Sri Lanka.

Adsorption kinetics of sugarcane bagasse for selective removal of Cr (VI) and Cu (II) from aqueous solutions

The Adsorption Kinetics for the simultaneous and selective removal of Cr(VI) and Cu(II) ions from aqueous mixture was investigated using sugarcane bagasse. Equal volumes of the laboratory prepared metal ion solutions of Cr(VI) and that of Cu(II), having the same initial concentration were mixed and used as test samples. Batch studies were performed at room temperature at three different initial concentrations of each metal ion to be present in the test sample: 10ppm, 30ppm and 50ppm. The available literature for the removal of each of these heavy metal ions when present individually in aqueous solutions was applied in these studies. Accordingly, water washed and sun dried sugarcane bagasse retained on 200 micron-mesh, was used for the study at a dosage of 0.4g/l of the test sample. No attempt was made to maintain a fixed pH as this involved addition of more chemicals adding to more contamination. Instead, the pH and remaining concentrations of the ions in the mixture after adsorption were monitored at various pre-set time intervals till equilibrium condition was attained. The pH of the test samples varied from 7.05 initial values to 8.09 at equilibrium, during all the batch studies. The study has revealed that the adsorbent had higher selectivity to Cu(II) ions in comparison to the Cr(VI) ions at the study conditions. The removal was faster and higher at low initial concentrations. The experimental results fit well with linearized Freundlich Adsorption Isotherm Model.

N Prapurna1 and M Viswanatham2
1Department of Chemical Engineering, CBIT, Hyderabad, India
2 Department of Civil Engineering, JNTUCE, Hyderabad, India

Environmental impacts on waste and water disposal from abbatoirs and poultry processing units in Weligama area.

Selling of Meat is one of the popular businesses among the Muslim community in the Weligama area. Therefore, the objective of the present study was to collect baseline data on the waste and water disposal methods and sanitary measures in abattoirs and poultry farms in the area. Selected abattoirs and poultry farms were visited to monitor the prevailing conditions and advice abattoirs and poultry farmers how to improve the standards in their working places. The results of this study revealed that all the abattoirs possess experience but little skill, knowledge and technology. All the visited abattoirs are situated close to residential areas, especially close to water bodies such as wells and streams. The reason is that the abattoirs need lot of water for cleaning and other purposes. Animals were killed on the floor just after cleaning with water. Approximately 100-150 kg meat was processed daily. The carcass recovery percentage was 50%; thereby waste generated was also 50% of the live weight of the animal. Approximately half of the waste contained bones, buried and used as fertilizer at a latter stage. Inedible parts of the digestive track and undigested material also buried, however, very close to the proximity of residential areas. The amount of water used was around 80-100 l/day but no proper way of disposing polluted water as it directly goes to drains, streams and opened wells etc. It was also observed that all the poultry cages and processing units were located very close to residential areas. Around 300 kg of poultry meat was produced daily. The carcass recovery was around 70-75% while the amount of waste generated was 25-30% of the live weight of a bird. Average waste material generated from a processing unit was around 75 kg/day. The offal’s were properly disposed due to collection by the urban council for compost making. It prevents environmental pollution and health hazards due to accumulation of offal and other wastes. Some processors were not involved in above programme and buried their wastes but complained that they do not have enough area for waste disposal.It is concluded that poultry processing involve with proper waste disposal methods. However, abattoirs use very unhygienic methods for waste disposal while no attention was focused on water pollution as well. Therefore, it is utmost important to educate the abattoirs for proper waste and water management techniques in order to minimize the environmental hazards.

N D C Sirisena, P A B S Baduwasam, R A U J Marapana and T Seresinghe
Department of Animal Science, University of Ruhuna, Sri Lanka