In the last few decades pollution associated with point and non-point sources have been identified as serious threat to water quality around the world. The demand for water in Mangaluru city of Dakshina Kannada district is 162 MLD and the present supply is 140 MLD. There are a number of industries situated in the vicinity of the coastal areas that discharge the treated effluents into the Arabian Sea. At present the total effluents discharged is 80MLD which is expected to increase with more industries to be commissioned in the Special Economic Zone (SEZ) and the expansion of the existing industries. Fresh water is most precious commodity in the earth so to protect this either it should be reused or recycled. Industrial utilization of fresh water is very high compared to the domestic use thus it is time to think how to utilize the same water after repeated treatment and making the industry as zero discharge.
Phytoremediation techniques are a low-cost alternative for wastewater treatment and in many cases, it could be coupled with nutrient recovery and biomass production (Srivastava et al. 2008).M/s. Mangalore Refineries and Petrochemicals Limited (MRPL) has advanced waste water treatment facilities.Of the treated waste 70% of it is re-usedand remaining is discharged into sea at 650 m seaward at Surathkal and Chitrapur. The effluent quantity is 30.375MLD. The effort of our studies is to make it more environmentally friendly technology so that the whole water of the industry can be reused.
Eicchornia crassipes is a highly adaptive aquatic plant and recently it has been identified as a means of producing biofuel. It is resistant to pest and diseases and naturally grows in stagnant ponds and lakes. It has high cellulose and lignin content per unit volume of dry matter.
Trials were conducted by using this plant in treated effluent water of Mangalore Petrochemicals and refinery Ltd. Standard methods were used to estimate the reduction in nutrients and pollutants. There was reduction in phosphate, ammonia, cyanide and sulphide level in the treated water within 6 days of treatment. Atomic absorption spectrophotometer for heavy metal analysis of the leaves showed an increase of 40% and 55% in Cu and Cd uptake. It was evident that the plant is capable of absorbing heavy metals in addition to reduction of nutrients. This will help the industry to further reduce the available nutrient load and heavy metals from the treated effluent if passed through the Eicchornia bed so that it can be reused in the industry. More experimental trials need to be conducted with better facilities to standardize the method and design structures for large scale treatment for effluent of water.