Hai-long Yin

Biological denitrification using corncobs as a carbon source and biofilm carrier.

In this research, agricultural waste--in particular, comcobs--was investigated for use as the sole carbon source and biofilm carrier to remove nitrate from wastewater in up-flow laboratory reactors. An artificial wastewater with a temperature range of 27 to 33 degrees C was used. Fast startup of the reactor and a high nitrate removal efficiency were observed. The highest denitrification rate of 0.203kg/(m3 x d) was achieved when flow rate and nitrate concentration were 153 L/d and 25.3 mgN/L, respectively. The accumulation of nitrite was not observed in this process. Moreover, flow rate and nitrate concentration of the influent were observed to have a significant effect on nitrate removal efficiency. A sharp decline of nitrate removal efficiency was observed when the flow rate was greater than 50 L/d. The reactor had the ability to accommodate a wide range of pH levels (6.5 to 8.5) and dissolved oxygen (1.5 mg/L to 4 mg/L). A time-dependent decrease in nitrate removal efficiency was observed after 67 days of operation. The addition of fresh corncobs brought about a rapid increase of nitrate removal efficiency. Results showed that corncobs could be used as an economical and effective carbon source for denitrification.

Study on improved BP artificial neural networks in eutrophication assessment of China eastern lakes

Abstract An improved back propagation artificial neural network model for eutrophication evaluation of China eastern was constructed, and a new approach producing training set data, testing set data and critical values set data distributed a normal distribution between the critical values was established. The model was applied to 4 eastern lakes and the results shows that the method is suitable for eutrophication assessment of lakes.

Numerical Modeling of Wastewater Transport and Degradation in Soil Aquifer

Modeling of wastewater transport and degradation in soil aquifer is a problem of concern with regard to the optimization of design and operation of the wastewater soil treatment system. To solve this problem, three-dimensional groundwater flow and wastewater transport and degradation model was developed using MODFLOW and MT3DMS modeling. The developed model was calibrated using the Soil Infiltration Treatment System (SITS) in the Chongming island of China after considering the river—groundwater interaction and the regional geological and hydrological conditions. Using the calibrated model, the following problems with regard to the design and operation of SITS were discussed: (1) Allowable hydraulic load. The hydraulic load increases with the drop in the water level of the adjoining river, the increase in the actual soil area under operation, and the increase in the distance among the individual operation units of SITS. (2) Optimized layout of the groundwater monitoring wells. The concentration contour of the simulated contaminants is very useful to depict the typical areas that are most severely polluted and very sensitive to the peripheral environment,, thus lesser number of monitoring wells can be set up based on the model, and the goal of the accurate assessment of the influence of soil-infiltrated wastewater on groundwater can be achieved.

The computation approach for water environmental capacity in tidal river network

Abstract Considering that the conventional systematical optimized method and the trail-and-error method are not efficient in computing water environment capacity of tidal river network, a new analytical computation approach to water environment capacity of tidal river network was presented. Furthermore, this new method was applied to estimate the water environment capacity of river network in Chongming Island after establishing hydrodynamic and water quality model, which shows the newly developed analytical computation approach efficient and reliable both in theory and in practice.

Development of integrated catchment and water quality model for urban rivers

This paper presents the development of an urban river water quality model which considers the physical-biochemical processes within rivers and the incorporated urban catchment rainfall-runoff process developed with the time–area method. Unlike other models that simulate the hydrological and receiving water quality processes in the rural areas of the watershed scale, the model developed here is typically efficient for simulating the water quality response to nonpoint loadings from urban drainage systems, where the hydrological process is disturbed by artificially pumped discharge in wet-weather periods. This model is employed to assess the river water quality restoration in Nanfei River in Hefei City, China, where the model is calibrated against the measured data (i.e., the COD, the BOD5, the NH3-N, and the DO) in 2010, and the model parameters are suggested. It is shown that the nonpoint pollutants from the urban catchments contribute 34%–47% of the total pollutant inputs (i.e., the COD, the BOD5, and the NH3-N), despite their low flow component of 13.4%. Apart from the improvement of the wastewater treatment plant effluent (i.e., Grade IV of the Surface Water Quality Standard), a nonpoint loading reduction of 27.2%, 25.1%, and 35.3% of the COD, the BOD5, and the NH3-N are anticipated to meet the designated surface water quality standards of Grade V.

OPTIMIZED DESIGN OF NATURAL ECOLOGICAL WASTEWATER TREATMENT SYSTEM BASED ON WATER ENVIRONMENT MODEL OF DYNAMIC MESH TECHNIQUE

A Natural Ecological Wastewater Treatment System (NEWTS) is usually built on natural terrain with necessary topography modification to improve water flowing route and pattern, and then the topography modified NEWTS should also have a reasonable water storage volume and hydraulic retention time so as to achieve the anticipated water purification effect. In this study, the dynamic mesh technique based on the finite element method and element storativity coefficients was presented to develop a two-dimensional hydrodynamic and water quality model, which was used to optimize the design of NEWTS under the dynamic land-water boundary due to various water storage volume. The models were employed in the optimized design of NEWTS from a large abandoned coal mine, which purifies the polluted water flowing into a large water storage lake, as part of the East Route South-to-North Water Transfer Project in China. Specifically, the natural topography modification scheme was presented, and further, a reasonable water storage volume and hydraulic residence time was obtained, based on the reasonable estimation of roughness coefficient and pollutant removal rate of the NEWTS with phragmites communis.

SIMULATION OF NON-POINT POLLUTANTS EVOLUTION IN COASTAL PLAIN ISLAND--A CASE STUDY OF CHONGMING ISLAND

The coastal plain region usually shows the agricultural dominated industry mode, so more and more attention is paid to non-point pollutants discharge. In this study, the method for assessing the influence of non-point pollutants discharge on river water quality is probed which is concluded as follows: (1) Considering the costal plain island is characterized as nearly even elevation, the conventional gravitational runoff confluence method based on eight-point gravitational flowing directions (D8) is unable to compute the runoff confluence received by the surrounding rivers, so a new method of triangular confluence based on three-points of grid center and the river segments is presented. Further the equations of non-point pollutants loads estimation and non-point pollutants confluence on rivers are presented. (2) The integration mode of non-point pollutants model and river water quality model is presented so as to further assess the non-point pollutants contribution to river water quality. (3) With the Chongming Island, the third largest island in China, as an example, the above-mentioned equations are specified. For this island, the non-point pollutants loads are estimated and linked to the developed water quality model of the river network in the island, and further the non-point pollution evolution in river network is simulated. In this scenario, the non-point pollution contribution to river water quality over the whole island is clearly displayed, and the area where the river water quality is seriously influenced by non-point pollutants discharge is distinctly depicted. This scenario also shows the water quality contribution ratio of non-point pollution to point pollution can be in the range of 55.5% to 44.5% which proves the importance of non-point pollution control in costal plain islands.

Transitional gravity flow of sewers inappropriate entry into storm drainage of a separate system

Transitional sewer flows into storm drainage were measured in Caohejing drainage system of Shanghai, a separate system with inappropriate sewage entry into storm drainage. Flowing measurement demonstrated the limitation of Hazzen-William equation on quantifying the gravity flows in sewers, so an empirical formula was established. The dimensionless coefficient ranges from 0.34 to 16.38, representing supercritical flow under river water surging into one underground sewer culvert, and subcritical flow under normal gravatational free fall. Based on field investigation, it was known that the dimensionless coefficient under normal free fall is in the range of 0.34–4.17, and correspondingly gravatational velocity of sewers inappropriate entry into storm drainage ranges from 0.06 m/s to 0.71 m/s under investigated sewer water depth 1–5 cm.

Eco-Hydraulics Techniques for Controlling Eutrophication of Small Scenery Lakes—A Case Study of Ludao Lake in Shanghai*

The Ludao Lake with an area of 0.86 km2 and 50% water surface ratio, was taken as an example to study the eco-hydraulics techniques for preventing lake eutrophication. Besides external water inflow and outflow, the term related to internal local flow circulation was added in the continuity equation of two-dimensional horizontal hydrodynamic model, and further the hydrodynamic model was calibrated by the scenario of no water exchange. The velocity of 0.2 m/s was suggested to be the critical velocity of controlling algal bloom. To achieve the critical velocity in the whole lake, three factors were analyzed, which are wind, artificial external inflow augmentation and internal local flow disturbance by pump circulation. It is found that the role of wind can be disregarded. For the eco-hydraulics technique of external lake water inflow augmentation, the water flowing route should be firstly optimized, further, the lake inflow has a critical value under specified water level due to the narrow inlets, so the whole lake is difficult to reach the critical velocity to prevent algal bloom, and a combination of external inflow augmentation and internal local flowing disturbance should be considered. Simulation results show that the combination of external water inflow augmentation and internal local flow disturbance requires less eco-flow to achieve the global critical velocity than the sole internal local flow disturbance, for the Ludao Lake, the former requires total eco-flow of 25 m3/s, which reduces by 50% than the latter requiring total eco-flow of 52 m3/s.

Identification of sewage markers to indicate sources of contamination: Low cost options for misconnected non-stormwater source tracking in stormwater systems

There has been increasing research focusing on the detection and occurrence of wastewater contamination in urban water systems. To find suitable markers to indicate industrial and domestic sewage flows inappropriately entering storm drains, this study investigated the occurrence and fate of 52 chemical markers through wastewater treatment facilities of manufacturers of agricultural and sideline products, beverage products, and pharmaceutical products, which are also consumed in our daily life. Of the 52 candidate markers, sodium, chloride, potassium, isomalto-oligosaccharide, acesulfame, theanine, glycerol, and clarithromycin were found to be conservative markers, with an average change in concentrations through the wastewater treatment processes of <30%. These markers are useful in identifying industrial and domestic sewage flow contamination in urban sewers. Specially, sodium, chloride, potassium, isomalto-oligosaccharide, acesulfame, and clarithromycin exhibited higher concentrations in blackwater than in greywater, with detected average concentrations of 43.8 mg/L, 189 mg/L, 37.3 mg/L, 123 μg/L, 37.2 μg/L, and 0.99 μg/L in blackwater, respectively. In contrast, theanine and glycerol were observed with higher concentrations in greywater than in blackwater (average 10.1 μg/L and 19.5 μg/L in greywater, respectively). The benchmark concentrations to discriminate between industrial and domestic sewage were also presented. A study in a storm drainage system of downstream Taihu catchment, China demonstrated the usefulness of the markers as low-cost options to trace and quantify misconnected wastewater entries into storm drains, while denoting priority areas for misconnected entries correction.