High Rate Algal Pond (HRAP) was constructed and operated using a mixer device to investigate its capability in treating greywater for reuse in gardening. Physico-chemical and microbiological parameters were monitored....High Rate Algal Pond (HRAP) was constructed and operated using a mixer device to investigate its capability in treating greywater for reuse in gardening. Physico-chemical and microbiological parameters were monitored. With a hydraulic retention time of 7.5 days and a solid retention time of 20 days, the average removal efficiencies (ARE) were 69% and 62% for BOD5 and COD respectively. The ARE for , and were 23%, 52% and 43% respectively. The removal of suspended solids (SS) was unsatisfactory, which could be attributed to the low average algal settling efficiencies of 9.3% and 16.0% achieved after 30 and 60 minutes respectively. The ARE of fecal coliforms, Escherichia coli and enterococci were 2.65, 3.14 and 3.17 log units respectively. In view of the results, the HRAP technology could be adapted for greywater treatment in sahelian regions. However, further studies on the diversity of the algal species growing in the HRAP unit are necessary in order to increase the removal of SS. Hazards of a reuse of the effluents are discussed on the basis of the various qualitative parameters. The residual content of E. coli was varying from 4 CFU per 100 mL. Based on WHO guidelines for greywater reuse in irrigation, the effluents could be used for restricted irrigation (E. coli < 105 CFU per 100 mL). Furthermore, the reuse potential is discussed on the basis of FAO guidelines using SAR (3.03 to 4.11), electrical conductivity (482 to 4500 μS/cm) and pH values (6.45 to 8.6).展开更多
The feasibility of an inexpensive wastewater treatment system is evaluated in this study.The experiment was conducted in 3 phases with different treatment combinations for testing theirpurification efficiencies. The p...The feasibility of an inexpensive wastewater treatment system is evaluated in this study.The experiment was conducted in 3 phases with different treatment combinations for testing theirpurification efficiencies. The pond system was divided into 3 functional regions: influentpurification, efficient upgrading and multi-utilization. Various kinds of aquatic organisms, wereeffectively cooperated in this system. The system attained high reduction of BOD_5, COD, TSS, TN,TP and other pollutants. The mutagenic effect and number of bacteria and virus significantly de-clined during the process of purifieation. After the wastewater flowed through the upgrading zone,the concentrations of pollutants and algae evidently decreased. Plant harvesting did not yield drama-tic effects on reductions of the main pollutants, through it did affect remarkably the biomassproductivity of the macrophytes. The wastewater was reclaimed for various purposes.展开更多
Based on the experiments of utilization of garlic processing wastewater in a lotus pond, this study demonstrates that lotus pond wetlands have a remarkable ability to remove organic pollutants and decrease chemical ox...Based on the experiments of utilization of garlic processing wastewater in a lotus pond, this study demonstrates that lotus pond wetlands have a remarkable ability to remove organic pollutants and decrease chemical oxygen demand （CODCr）, biochemical oxygen demand （BOD5）, and suspended substances （SS） in garlic processing wastewater. Results also show evident effects of lotus roots on absorption of NH3-N. The pH value in a lotus pond with wastewater discharged was relatively stable. The water quality in the lotus pond reached the class Ⅱ emission standard, according to the Integrated Wastewater Discharge Standard （GB8978-1996）, seven days after pretreated garlic processing wastewater had been discharged into the lotus pond. Garlic processing wastewater irrigation does not produce pollution in the pond sediment and has no negative effect on the growth of lotus roots. Due to utilization of garlic processing wastewater, the output of lotus roots increased by 3.0% to 8.3%, and the quality of lotus roots was improved. Therefore, better purification and utilization results can be achieved.展开更多
Two kinetic models were established for conservative estimates of photodegradation rates of contaminants under sunlight irradiation,in particular for wastewater stabilisation ponds and clarifiers in conventional waste...Two kinetic models were established for conservative estimates of photodegradation rates of contaminants under sunlight irradiation,in particular for wastewater stabilisation ponds and clarifiers in conventional wastewater treatment plants.These two models were designated for(1)contaminants with high photolytic rates or high photolytic quantum yields,whose photodegradation is unlikely to be enhanced by aquatic photosensitisers;and(2)contaminants withstanding direct photolysis in sunlit waters but subjected to indirect photolysis.The effortlessly intelligible prediction procedure involves sampling and analysis of real water samples,simulated solar experiments in the laboratory,and transfer of the laboratory results to realise water treatment using the prediction models.Although similar models have been widely used for laboratory studies,this paper provides a preliminary example of translating laboratory results to the photochemical fate of contaminants in real waters.展开更多
Pesticides provide the primary means for controlling organisms that compete with man for food and fibre or cause injury to man, livestock and crops. They played a vital role in the economic production of wide ranges o...Pesticides provide the primary means for controlling organisms that compete with man for food and fibre or cause injury to man, livestock and crops. They played a vital role in the economic production of wide ranges of vegetable, fruit, cereal, forage, fibre and oil crops which now constitute a large part of successful agricultural industry in many countries. After application to the target areas, pesticide residues are removed from applicators by rinsing with water which results in the formation of a toxic wastewater that represents a disposal problem for many farmers. Pesticides can adversely affect people, pets, livestock and wildlife in addition to the pests they are intended to destroy. The phenomenon of biomagnification of some pesticides has resulted in reproductive failure of some fish species and egg shell thinning of birds such as peregrine falcons, sparrow hawk and eagle owls. Pesticide toxicity to humans include skin and eye irritation and skin cancer. Therefore, care must be exercised in the application, disposal and treatment of pesticides. Currently, disposal of pesticide wastewater is carried out by: 1) land cultivation, 2) dumping in soil pits, plastic pits and concrete pits or on land and in extreme cases in streams near the rinsing operation, 3) use of evaporation beds and 4) land filling. These methods of disposal are unsafe as the surface run off will reach streams, rivers and lakes and the infiltration of the wastewater into the local soil will eventually reach ground water. The treatment methods currently used for pesticide wastewater include: 1) incineration (incinerators and open burning), 2) chemical treatments (O3/UV, hydrolysis, Fenton oxidation and KPEG), 3) physical treatments (inorganic, organic absorbents and activated carbon) and 4) biological treatments (composting, bioaugmentation and phytoremediation). Therefore, the choice of safe, on farm disposal techniques for agricultural pesticides is very important. A comparative analysis was performed on 18 methods of pesticide disposal/treatment using six criteria: containment, detoxification ability, cost, time, suitability for on farm use, size and evaporation efficiency. The results indicated that of the 18 methods evaluated, 9 scored above 80/100 and can be used on farm. They were organic absorbents (97), composting (94), bioaugmentation (92), inorganic absorbents (90), Fenton oxidation (86), O3/UV (83), activated carbon (82), hydrolysis (82), and land cultivation (80). The other methods are not suitable for on farm use as they suffered from containment problems, high cost and variability of effectiveness.展开更多
文摘High Rate Algal Pond (HRAP) was constructed and operated using a mixer device to investigate its capability in treating greywater for reuse in gardening. Physico-chemical and microbiological parameters were monitored. With a hydraulic retention time of 7.5 days and a solid retention time of 20 days, the average removal efficiencies (ARE) were 69% and 62% for BOD5 and COD respectively. The ARE for , and were 23%, 52% and 43% respectively. The removal of suspended solids (SS) was unsatisfactory, which could be attributed to the low average algal settling efficiencies of 9.3% and 16.0% achieved after 30 and 60 minutes respectively. The ARE of fecal coliforms, Escherichia coli and enterococci were 2.65, 3.14 and 3.17 log units respectively. In view of the results, the HRAP technology could be adapted for greywater treatment in sahelian regions. However, further studies on the diversity of the algal species growing in the HRAP unit are necessary in order to increase the removal of SS. Hazards of a reuse of the effluents are discussed on the basis of the various qualitative parameters. The residual content of E. coli was varying from 4 CFU per 100 mL. Based on WHO guidelines for greywater reuse in irrigation, the effluents could be used for restricted irrigation (E. coli < 105 CFU per 100 mL). Furthermore, the reuse potential is discussed on the basis of FAO guidelines using SAR (3.03 to 4.11), electrical conductivity (482 to 4500 μS/cm) and pH values (6.45 to 8.6).
文摘The feasibility of an inexpensive wastewater treatment system is evaluated in this study.The experiment was conducted in 3 phases with different treatment combinations for testing theirpurification efficiencies. The pond system was divided into 3 functional regions: influentpurification, efficient upgrading and multi-utilization. Various kinds of aquatic organisms, wereeffectively cooperated in this system. The system attained high reduction of BOD_5, COD, TSS, TN,TP and other pollutants. The mutagenic effect and number of bacteria and virus significantly de-clined during the process of purifieation. After the wastewater flowed through the upgrading zone,the concentrations of pollutants and algae evidently decreased. Plant harvesting did not yield drama-tic effects on reductions of the main pollutants, through it did affect remarkably the biomassproductivity of the macrophytes. The wastewater was reclaimed for various purposes.
基金supported by the Key Project of Environmental Science and Technology of Shandong Province(Grant No.2006003-2)
文摘Based on the experiments of utilization of garlic processing wastewater in a lotus pond, this study demonstrates that lotus pond wetlands have a remarkable ability to remove organic pollutants and decrease chemical oxygen demand （CODCr）, biochemical oxygen demand （BOD5）, and suspended substances （SS） in garlic processing wastewater. Results also show evident effects of lotus roots on absorption of NH3-N. The pH value in a lotus pond with wastewater discharged was relatively stable. The water quality in the lotus pond reached the class Ⅱ emission standard, according to the Integrated Wastewater Discharge Standard （GB8978-1996）, seven days after pretreated garlic processing wastewater had been discharged into the lotus pond. Garlic processing wastewater irrigation does not produce pollution in the pond sediment and has no negative effect on the growth of lotus roots. Due to utilization of garlic processing wastewater, the output of lotus roots increased by 3.0% to 8.3%, and the quality of lotus roots was improved. Therefore, better purification and utilization results can be achieved.
文摘Two kinetic models were established for conservative estimates of photodegradation rates of contaminants under sunlight irradiation,in particular for wastewater stabilisation ponds and clarifiers in conventional wastewater treatment plants.These two models were designated for(1)contaminants with high photolytic rates or high photolytic quantum yields,whose photodegradation is unlikely to be enhanced by aquatic photosensitisers;and(2)contaminants withstanding direct photolysis in sunlit waters but subjected to indirect photolysis.The effortlessly intelligible prediction procedure involves sampling and analysis of real water samples,simulated solar experiments in the laboratory,and transfer of the laboratory results to realise water treatment using the prediction models.Although similar models have been widely used for laboratory studies,this paper provides a preliminary example of translating laboratory results to the photochemical fate of contaminants in real waters.
文摘Pesticides provide the primary means for controlling organisms that compete with man for food and fibre or cause injury to man, livestock and crops. They played a vital role in the economic production of wide ranges of vegetable, fruit, cereal, forage, fibre and oil crops which now constitute a large part of successful agricultural industry in many countries. After application to the target areas, pesticide residues are removed from applicators by rinsing with water which results in the formation of a toxic wastewater that represents a disposal problem for many farmers. Pesticides can adversely affect people, pets, livestock and wildlife in addition to the pests they are intended to destroy. The phenomenon of biomagnification of some pesticides has resulted in reproductive failure of some fish species and egg shell thinning of birds such as peregrine falcons, sparrow hawk and eagle owls. Pesticide toxicity to humans include skin and eye irritation and skin cancer. Therefore, care must be exercised in the application, disposal and treatment of pesticides. Currently, disposal of pesticide wastewater is carried out by: 1) land cultivation, 2) dumping in soil pits, plastic pits and concrete pits or on land and in extreme cases in streams near the rinsing operation, 3) use of evaporation beds and 4) land filling. These methods of disposal are unsafe as the surface run off will reach streams, rivers and lakes and the infiltration of the wastewater into the local soil will eventually reach ground water. The treatment methods currently used for pesticide wastewater include: 1) incineration (incinerators and open burning), 2) chemical treatments (O3/UV, hydrolysis, Fenton oxidation and KPEG), 3) physical treatments (inorganic, organic absorbents and activated carbon) and 4) biological treatments (composting, bioaugmentation and phytoremediation). Therefore, the choice of safe, on farm disposal techniques for agricultural pesticides is very important. A comparative analysis was performed on 18 methods of pesticide disposal/treatment using six criteria: containment, detoxification ability, cost, time, suitability for on farm use, size and evaporation efficiency. The results indicated that of the 18 methods evaluated, 9 scored above 80/100 and can be used on farm. They were organic absorbents (97), composting (94), bioaugmentation (92), inorganic absorbents (90), Fenton oxidation (86), O3/UV (83), activated carbon (82), hydrolysis (82), and land cultivation (80). The other methods are not suitable for on farm use as they suffered from containment problems, high cost and variability of effectiveness.
