Purification of pulp and paper mill effluent using Eichornia crassipes

Synthesis of high-length calcium sulfate whisker, an ideal substitute of the plant-based pulp fiber for papermaking

As a byproduct of the industrial synthesis of phosphoric acid, there was a large quantity of phosphor gypsum (PG) accumulation, which needs enormous storage space and endangers the environment. The preparation of calcium sulfate whisker (CSW) from waste PG could solve the large amounts of PG accumulation and substitute the plant-based pulp fiber, reducing the pollution of wastewater in paper and pulp industries. In this work, the CSW, which length could reach 230 μm, was fabricated from the PG in a glycerol-water solution. It could be found that the glycerol-water volume ratio of 4:6 was the best ratio that could reduce the water activity and accelerate the phase transition from calcium sulfate dihydrate (CSD) to CSW. Meanwhile, the CSW, after calcination, could prepare the anhydrous calcium sulfate whisker (ACSW) with low solubility in water; when the ACSW substitution rate reached 50%, the property of the complex paper could still satisfy the standard of mechanical and optical for offset book paper.

Phytoextraction of endosulfan a remediation technique

Endosulfan is a cyclodiene insecticide used all over the world for the control of various insect pests on variety of food and non crop products. Despite judicious use endosulfan has been detected in atmosphere, soil, water, sediment, surface water rain water and food stuffs, which is of concern. In view of the above the use of mustard and maize plants as potential phytoremediation inputs have been evaluated. The potential of mustard (brassica campestris Linn.) and maize (Zea Maize) to remove a organochlorine pesticide endosulfan was investigated. The disappearance rate constants of endosulfan from soil were 0.03684, 0.23490 and 0.17272 day(-1) for unplanted treatment, planted with mustard and maize, respectively, which implied that plant uptake and phytoextraction with maize and mustard contributed 47.2% and 34.5%, respectively and other degradation processes took up 38.7% and 35.9%, respectively to the removal of the applied endosulfan from soil. The accumulated endosulfan decreased by 55%-91% in soil after growing the crop plants in soil, suggesting that plant uptake and phytoextraction might be the dominant process for endosulfan removal by the plant. This plant might be utilized as an efficient, economical and ecological alternative to accelerate the removal and degradation of agro-industrial wastewater polluted with endosulfan.

Efficiency of combined process of ozone and bio-filtration in the treatment of secondary effluent

The present work was aimed at studying the efficiency of the combined process of biofiltration with ozonation to improve the quality of secondary effluent. The secondary effluent from the Dinapur Sewage Treatment Plant Varanasi, India was used in this work. The process of biofiltration with the plant species of Eichornia crassipes and Lemna minor, at a flow rate of 262 ml min(-1) and plant density of 30 mg L(-1) for 48 h, in combination with the process of ozonation with ozone dose of 10 mg L(-1) and contact time of 5 min was applied. Results revealed that combined process was statistically most suitable for the highest degradation of physico-chemical and microbial parameters with improving BDOC value. The biofiltration process is able to remove highest percentage of toxic heavy metals from the secondary effluent without production of toxicity. This technique is highly recommendable for tropical wastewater where sewage is mixed with industrial effluents.

Physicochemical characteristics of paper industry effluents--a case study of South India Paper Mill (SIPM)

Pulp and paper mills generate varieties of pollutants depending upon type of the pulping process being used. This paper presents the characteristics of wastewater from South India Paper Mill, Karnataka, India which is using recycled waste paper as a raw material. The raw wastewater consists of 80-90 mg L( - 1) suspended solid and 1,010-1,015 mg L( - 1) dissolved solid. However, pH varied from 5.5-6.8. The biochemical oxygen demand and chemical oxygen demand ranged from 200-210 and 1,120-1,160 mg L( - 1), respectively. Aerobic treatment of raw effluent attribute to significant reduction in suspended solid (range between 25 to 30 mg L( - 1)) and total dissolved solid (range between 360 to 390 mg L( - 1)). However, pH, temperature, and electrical conductivity were found superior after treatment. Copper, cadmium, iron, lead, nickel, and zinc were found in less quantity in raw effluent and were almost completely removed after treatment. The dendrogram of the effluent quality parameters clearly indicate that South India Paper Mill does not meet Minimal National Standard set by central Pollution Control Board to discharge in agricultural field.