The importance of the treatment plant performance during rain to acute water pollution

1996 ◽  
Vol 34 (3-4) ◽  
pp. 1-8 ◽  
Author(s):  
W. Rauch ◽  
P. Harremoës

Rain causes not only pollution loads from combined sewer overflows but also from treatment plants. High hydraulic load conditions can affect the secondary clarifier performance, resulting in a massive loss of sludge from the plant. The consequence to the oxygen concentration in the recipient can be described by the same simplified mechanism, because the principle remains the same. The difference that has to be accounted for, is the different organic characteristics of the discharged water. The analysis of a hypothetical urban drainage system by means of a deterministic model reveals the importance of the treatment plant in this respect. Oxygen depletion in urban rivers is caused by intermittent discharges from both sewer system and wastewater treatment plant. Neglecting one of them in the evaluation of the environmental impact gives a wrong impression of total system behavior. Linear sensitivity analysis provides useful information for water quality management. The significant parameters in terms of acute water pollution are identified.

1997 ◽  
Vol 36 (8-9) ◽  
pp. 179-184 ◽  
Author(s):  
W. Rauch ◽  
P. Harremoës

Oxygen and ammonia concentration are key parameters of acute water pollution in urban rivers. These two abiotic parameters are statistically assessed for a historical rain series by means of a simplified deterministic model of the integrated drainage system. Continuous simulation of the system performance indicates that acute water pollution is caused by intermittent discharges from both sewer system and wastewater treatment plant. Neglecting one of them in the evaluation of the environmental impact gives a wrong impression of total system behavior. Detention basins and alternative operational modes in the treatment plant under wet weather loading have a limited positive effect for minimizing acute water pollution.


2002 ◽  
Vol 45 (3) ◽  
pp. 229-237 ◽  
Author(s):  
T. Frehmann ◽  
A. Niemann ◽  
P. Ustohal ◽  
W.F. Geiger

Four individual mathematical submodels simulating different subsystems of urban drainage were intercoupled to an integral model. The submodels (for surface runoff, flow in sewer system, wastewater treatment plant and receiving water) were calibrated on the basis of field data measured in an existing urban catchment investigation. Three different strategies for controlling the discharge in the sewer network were defined and implemented in the integral model. The impact of these control measures was quantified by representative immission state-parameters of the receiving water. The results reveal that the effect of a control measure may be ambivalent, depending on the referred component of a complex drainage system. Furthermore, it is demonstrated that the drainage system in the catchment investigation can be considerably optimised towards environmental protection and operation efficiency if an appropriate real time control on the integral scale is applied.


1998 ◽  
Vol 38 (11) ◽  
pp. 97-104 ◽  
Author(s):  
Wolfgang Rauch ◽  
Hans Aalderink ◽  
Peter Krebs ◽  
Wolfgang Schilling ◽  
Peter Vanrolleghem

The design of efficient technical measures for the abatement of water pollution requires that wastewater discharge regulations are driven by receiving water objectives. However, such integrated water quality management is only possible when the impact to the aquatic ecosystem can be predicted quantitatively by means of integrated wastewater models. Typically, only a few types of wastewater discharge impacts are relevant for the state of the receiving water and, consequently, the structure of the model can be kept relatively simple when focusing on one of these impacts. The procedure of problem-oriented model selection is illustrated for three typical examples of acute water pollution, that is toxicity from un-ionized ammonia, hygienic hazard from pathogenic micro-organisms and oxygen depletion.


2005 ◽  
Vol 52 (8) ◽  
pp. 273-278 ◽  
Author(s):  
O. Braga ◽  
G.A. Smythe ◽  
A.I. Schafer ◽  
A.J. Feitz

The concentrations of two natural estrogens (estrone (E1) and Estradiol (E2)) and one synthetic progestin (Ethinylestradiol (EE2)) were measured for different unit operations in an advanced sewage treatment plant and in a large coastal enhanced primary sewage treatment plant. The average influent concentration to both plants was similar: 55 and 53ng/L for E1 and 22 and 12ng/L for E2 for the advanced and enhanced primary STPs, respectively. The activated sludge process at the advanced STP removed up to 85% and 96% of E1 and E2, respectively. The enhanced primary sewage treatment plant was mostly ineffective at removing the steroids with only 14% of E1 and 5% of E2 being removed during the treatment process. EE2 was not been detected during the study period in the influent or effluent of either STP. The difference in the observed removal between the two plants is primarily linked to plant performance but the extent to which removal of steroid estrogens is due to bacterial metabolism (i.e. the advanced STP) rather than adsorption to the bacterial biomass remains unclear. The poor removal observed for the coastal enhanced primary STP may have implications for the receiving environment in terms of a greater potential for abnormal reproductive systems in marine animals, particularly if discharges are into large bays or harbours where flushing is limited.


1996 ◽  
Vol 31 (3) ◽  
pp. 453-472 ◽  
Author(s):  
M. Stirrup

Abstract The Regional Municipality of Hamilton-Wentworth operates a large combined sewer system which diverts excess combined sewage to local receiving waters at over 20 locations. On average, there are approximately 23 combined sewer overflows per year, per outfall. The region’s Pollution Control Plan, adopted by Regional Council in 1992, concluded that the only reasonable means of dealing with large volumes of combined sewer overflow in Hamilton was to intercept it at the outlets, detain it and convey it to the wastewater treatment plant after the storm events. The recommended control strategy relies heavily on off-line storage, with an associated expansion of the Woodward Avenue wastewater treatment plant to achieve target reductions of combined sewer overflows to 1–4 per year on average. The region has begun to implement this Pollution Control Plan in earnest. Three off-line detention storage tanks are already in operation, construction of a fourth facility is well underway, and conceptual design of a number of other proposed facilities has commenced. To make the best possible use of these facilities and existing in-line storage, the region is implementing a microcomputer-based real-time control system. A number of proposed Woodward Avenue wastewater treatment plant process upgrades and expansions have also been undertaken. This paper reviews the region's progress in implementing these control measures.


1990 ◽  
Vol 22 (10-11) ◽  
pp. 69-76 ◽  
Author(s):  
A. Durchschlag

As a result of urbanization, the pollutant discharges from sources such as treatment plant effluents and polluted stormwaters are responsible for an unacceptable water quality in the receiving waters.In particular, combined sewer system overflows may produce great damage due to a shock effect. To reduce these combined sewer overflow discharges, the most frequently used method is to build stormwater storage tanks. During storm water runoff, the hydraulic load of waste water treatment plants increases with additional retention storage. This might decrease the treatment efficiency and thereby decrease the benefit of stormwater storage tanks. The dynamic dependence between transport, storage and treatment is usually not taken into account. This dependence must be accounted for when planning treatment plants and calculating storage capacities in order to minimize the total pollution load to the receiving waters. A numerical model will be described that enables the BOD discharges to be continuously calculated. The pollutant transport process within the networks and the purification process within the treatment plants are simulated. The results of the simulation illustrate; a statistical balance of the efficiency of stormwater tanks with the treatment plant capacity and to optimize the volume of storm water tanks and the operation of combined sewer systems and treatment plants.


1991 ◽  
Vol 23 (1-3) ◽  
pp. 41-48
Author(s):  
Yin Jun

The paper takes the Second Songhua River as an object for research and selects Thomas's BOD-DO stable model as the initial structure on the basis of overall investigations and analyses on water pollution in every reach. In view of the characteristics of the river being located at the north, values k’1, k’2 and k’3 in dry season of winter were determined and calculated, and a series analyses have been made. The self-purification ability of the river and the total elimination amount of the main pollutants BOD5 were also calculated. In order to minimize the required cost, we distributed the cost to the main pollution sources, which are to be controlled. We firstly set a cost function of sewage treatment plant by series design and calculated the related cost parameters, then calculated two kinds of optimal distributing models of BOD5 elimination, which were a mathematical model of extreme value of conditions and a matrix mathematical model. Now they have been applied to the practical pollution control plan for the Second Songhua River.


1991 ◽  
Vol 23 (1-3) ◽  
pp. 29-39 ◽  
Author(s):  
Ken Murakami

Due to rapid industrialization and the concentration of the population shifting towards large cities starting from the 1950s, Japan experienced severe water pollution problems throughout the country. In order to cope with these problems, the legal system has been refined and various measures to control water pollution have been taken. This paper summarizes the current institutional structure, legal system, as well as plans and programs, for water pollution control and river basin management in Japan.


1991 ◽  
Vol 24 (5) ◽  
pp. 189-196 ◽  
Author(s):  
S. B. Guo ◽  
R. Z. Chen ◽  
G. Li ◽  
H. Y. Shoichi

In 1987 Guangzhou Liede Nightsoil Treatment Plant started commissioning. The purpose of the plant is to dispose of 400 tons of nightsoi1 from city public toilets per day. In the first year of the commissioning a biological process was basically used according to the original design made by a Danish company. Practically it has been proved that the design is effective. The process can reduce BOD from 3800 mg/l to about 133 mg/l, or by approximately 96.5 percent. The performance of the sludge digester system is satisfactory. Because the primary investigation on characteristics of the nightsoil was insufficient there were some problems raised during the commissioning. So in the first year the effluent failed to achieve the desired quality. After the analysis of the plant performance some necessary reforms have been carried out. Now the effluent quality can stably meet the national discharge limits and the treatment cost decreases.


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