Research on enhanced coagulation test for sludge water recycling in water treatment plant in Ganjiang River Nanchang Section

With raw water from Ganjiang River Nanchang Section as the research object and dosage, sludge water reflux ratio and reflux concentration as the control parameters, coagulation reflux and orthogonal test is designed to measure water quality indicators of the unfiltered water such as turbidity, chemical oxygen demand (CODMn), partial metal concentration and total bacterial count. The test demonstrates that: sludge water reflux may enhance the coagulation, promote the quality of the precipitated water and save dosage. Within a certain range, the lower the dosage, the more obvious the effect of enhanced coagulation; the best result was obtained under the low concentration mud water (turbidity of 40-50 NTU) reuse conditions, with the 10% return ratio and the dosing rate of 10 mg/L; there is a certain linear relationship between the sludge water concentration and the recycling amount, that is, the product of them is stable within a certain range; the analysis shows that CODMn, ammonia nitrogen, total phosphorus, partial metal concentration, the total bacterial count and fecal coliforms of the sedimentation basin effluent will not increase significantly by reasonable control of the reflux parameters when returning high concentration sludge water (turbidity is about 500 NTU), the overall risk of subsequent reuse is manageable and there are no safety issues. CODMn is the lowest when the reflux ratio is between 4% and 6%, ammonia nitrogen and total phosphorus are both at their lowest when the reflux ratio is between 2% and 4%, When the reflux ratio is controlled at 4%, the total bacterial and fecal coliform counts are prevented from increasing too rapidly and there is no significant accumulation of Al, Fe and Mn in the effluent. The orthogonal experiment shows that for turbidity removal, the dosage plays a major role, and the reuse of sludge water can further strengthen coagulation on this basis. The research results can provide certain theoretical and data references for the sludge water reflux system in water treatment plants in the Ganjiang River Nanchang Section.

Automated summary

By controlling the parameters and analyzing the test results, it can be determined that within a certain range, the lower the dosage, the better the effect; under conditions of low concentration sludge water reuse, the effect is even better; reasonable control of the reflux parameters can prevent significant increase of water quality indicators in the effluent of the sedimentation basin, making the risk controllable.