Wiley Wastewater Quality Monitoring and Treatment_19 docx

Despite the fact that the Hazard Analysis and Critical Control Points HACCP concept is increasingly used to direct efforts in process control and monitoring to guarantee hygienically saf

The Water Reclamation Technology Involved 337

or without nutrient removal), tertiary (with attached bar for main tertiary treatment processes) or quaternary (multi-barrier systems including a double membrane unit) –

attached to them in different regions of the world (Bixio et al., 2005).

For each treatment process, there are typically well-defined standard Quality As-surance/Quality Control (QA/QC) practices to assure that the system is functioning

as designed (Bixio and Wintgens, 2006) While their description goes beyond the scope of this document, it is worth mentioning that on-line, real-time water quality monitoring is extensively used for this purpose and that the degree of satisfac-tion of the respondents of the Aquarec quessatisfac-tionnaire with on-line sensors is very high

Such indirect indicators that detect, on-line, possible integrity defects, are partic-ularly desired for those parameters that cannot be monitored directly on-line or in rapid repetition, e.g hygienic parameters

Moreover, some technologies can introduce additional water quality concerns For instance, by-products of disinfection processes (DBP) may yet prove to be among the greatest chemical concerns in reclaimed water In recent years atten-tion has been given to the detecatten-tion of the potent carcinogen, nitrosodimethylamine (NDMA) in chlorinated sewages intended for reuse Besides, we have seen that chloride levels can be of concern also for certain reuse application, for instance in irrigation because high levels are toxic to many plants Dechlorination is sometimes required

The type of distribution system also contributes to the setting of the appropri-ate monitoring strappropri-ategy For instance, long distribution systems may need a disin-fection residual, or contamination in the distribution system or cross-connections may negate any of the benefits of the water reclamation step Many respondents of the Aquarec questionnaire gave particular importance to the control of reticulation systems especially where reclaimed water is reticulated in close proximity to potable supplies

Several types of contractual agreements were identified to limit the liability of the water supplier on the one hand, and to ensure that operation and maintenance is practised in a safe and responsible manner, on the other The experience in Australia,

at Sydney Olympic Park (Listowski, 2004) and at Rouse Hill in Sydney (De Rooy and Engelbrecht, 2003) is to manage the system with comprehensive inspection during construction and with follow-up inspections and certification In Israel, in the case

of a pipe leakage the farmer is immediately notified and the water utility will have

to repair the leakage in a time delay of up to 24 h Water supply interruptions of 24 h can be sufficient for some crops to deteriorate

Despite the fact that the Hazard Analysis and Critical Control Points (HACCP) concept is increasingly used to direct efforts in process control and monitoring to guarantee hygienically safe reclaimed water, very few surveyed projects have used this approach to set up their monitoring programme Two examples are the multi-purpose NEWater scheme in Singapore (Leong Yin Hou, personal communication)

and the artificial aquifer recharge project in Wulpen, Belgium (Dewettinck et al.,

2001)

5.4.4 INHERENT CONSTRAINTS OF ANALYTICAL

PROCEDURES AND SENSORS

Several water quality indicators are difficult – and costly – to analyse and the time to conduct the analysis is too long (e.g several microbial parameters as well as chemical compounds such as copper, iron and manganese) to avert potential problems Because of the preventive measures that are generally in place (including a multi-barrier protection of the intended reclaimed water use), within the European Union monitoring of delivered water quality is simply verification that the preventative measures are effective, and often variables that can be monitored instantaneously can give a higher level of confidence in safety of supply and at less cost than analysing for an expanding number of chemicals

The monitoring of operating parameters continuously is a standard component

of all water reclamation schemes investigated Minimum instrumentation consisted

of alarms at critical treatment units to alert an operator of a malfunction Sensors that are available in almost all the water reclamation schemes in order to identify and halt the use of unacceptable reclaimed water quality are conductance meters and turbidometers (high levels of turbidity can protect micro-organisms from the effects of disinfection, stimulate the growth of bacteria, and exert a higher chlorine demand for disinfection) The disinfectant residual is also measured continuously and often the signal is used in automatic control systems Note that the consequences

of barrier failure were not considered by the operators to be of significance, either because there were multiple barriers in the schemes or because the end-user can tolerate some water quality that is below normal standards

The water quality parameters most commonly monitored in wastewater treatment plant effluent and water reuse schemes and their frequency for different types of end-uses are given in Table 5.4.3 (reference costs are based on Western European values)

Note that the frequency may be dependent on the size of the installation and that in some legislation defined frequencies may be reduced by demonstration of appropriate effluent quality

5.4.5 TRENDS

5.4.5.1 A More Varied List of Reclaimed Water Quality Indicators

The state of science is not yet reflected in water reuse guidelines or regulation and there is an open debate about the relevance of several additional water quality indicators for water reuse applications

In the first place, the debate is on the microbiological indicators Besides the tradi-tionally established indicator organisms for the potential occurrence of pathogenic

or-ganisms such as faecal coliforms or Escherichia coli, a range of emerging pathogens

has been discussed and investigated as well as new detection methods such as

H4

− 2 ,N

− 3 ,S

339

fluorescence in-situ hybridization (FISH) and polymerase chain reaction (PCR).

Some pathogens are already included in guidelines and legislation Florida for

in-stance recognizes that Giardia spp and Cryptosporidium spp are pathogens of

increasing importance to water reclamation and now requires monitoring for these pathogens Another increasing concern is caused by the still growing multiple an-tibiotic resistances of human pathogens (Mart´ınez and Baquero, 2002)

Second, an increasingly documented class of organic trace contaminants in wastewater is that of the ‘endocrine disrupting chemicals’ Much attention has been devoted to natural and synthetic steroidal hormones, which are shown to in-duce biological effects on some organisms at part per trillion concentrations Some steroidal hormones are poorly removed in conventional wastewater treatment

pro-cesses (Purdom et al., 1994) Other chemicals exhibiting similar effects at higher

concentrations that are known to be present in sewages include some plasticizers,

pesticides and degradation products of some detergents (K¨orner et al., 2000).

Third, there is also a broad range of pharmaceutically active compounds which have been detected in municipal wastewaters in many parts of the world (Heberer, 2002) At this point there are no indications for limitations to water reuse caused by these compounds, although their effect is largely unknown

There are currently no analytical standard procedures for a range of emerging pollutants such as endocrine disrupters and pharmaceuticals

There has been an extensive effort to investigate emerging organic trace contam-inants in wastewater streams and assess the removal capacity of both conventional and advanced wastewater treatment options (Poseidon, 2004) It is very obvious that sophisticated analytical techniques are required to measure most of the trace organic contaminants in realistic concentrations as found in wastewater treatment plant effluents (Kuch and Ballschmiter, 2000)

Apart from chemical analysis approaches to monitor emerging trace pollutants there have been many approaches to establish and apply biological effect assays, which do not look at the identification of single compounds but of cumulative effects

of a water sample on a test cell line (in vitro assay) or on complex organisms (in vivo tests) (Segner et al., 2003) Besides acute toxicity, chronic and sublethal aspects such

as genotoxicity and mutagenicity are of increasing importance as well as endocrine

disruption and immunotoxicity (P´erez et al., 2003) Bioassays can prove to be very

effective in the monitoring of both reclaimed water quality and water reuse impact

(Valat et al., 2004).

As part of the ongoing investigation of the behaviour of emerging contaminants in wastewater reclamation and reuse the Reclaim Water project applies a comprehen-sive analytical package for the monitoring of a number of water reuse case studies (www.reclaim-water.org) Within the project, standard analytical parameters (see Ta-ble 5.4.2) as well as emerging microbial and chemical contaminants are considered

in combination with biological effect assays (Table 5.4.4)

In some advanced wastewater reclamation schemes, particularly for indirect potable reuse, already very comprehensive monitoring campaigns are carried out The example of the Singaporean NeWater Project given in Table 5.4.5 shows the

Trends 341

Table 5.4.4 Intensified analysis program for water reuse sites which is being carried out in the

RECLAIM WATER project (www.reclaim-water.org)

Specific microbial contamination and antibiotic

Bacteria

Salmonella spp., Campylobacter jejuni,

Yersinia enterocolitica, Francisella tularensis,

Helicobacter pilori, Mycobacterium avium

Antibiotics e.g sulfamethoxazole, tetracycline

Protozoa

Cryptosporidium spp., Giardia spp.

Organic tracer compounds and endocrine disruptors

e.g iodated contrast media, adsorbable organic iodine, carbamazepine, benzotriazole, diclofenac Viruses

Enterovirus (Poliovirus, Echovirus,

Coxsackievirus), Hepatitis A virus, Rotavirus

Dissolved organic matter characterization e.g natural organic matter and effluent organic matter fractions

Helminth eggs

Ascaris lumbricoides, Trichurus trichiura,

Anclylostoma duodenale

Disinfection byproducts

e.g N-nitrosamines, trihalomethanes

Antibiotic resistance gene

Table 5.4.5 Number and nature of monitored parameters per sampling location at the NeWater

reclamation facility, Singapore (redrawn from Public Utilities Board, 2002)

Sample location

PUB

Inorganic Disinfection

byproducts

byproducts

Wastewater signature

compounds

Synthetic and

natural hormones

intensive monitoring efforts that have been made in the early phase of the project

to confirm that there is no concern with respect to residual levels of trace contam-inants Currently, for the routine operation an extensive sampling and monitoring programme, which includes 278 parameters, is in place (Leong Yin Hou, personal communication)

In summary, it can be noted that there is a clear trend for more comprehensive monitoring which is based on more powerful analytical techniques both in the mi-crobiological and chemical sector

A key recommendation for operators is to make use of specialized laboratories for a baseline assessment of emerging parameters without the necessity to include them in routine analysis at this stage

It is a research task to assess both the relevance and most efficient removal tech-niques for a wider range of emerging contaminants Instead of widely enlarged parameter catalogues an opportunity would be to establish advanced treatment stan-dards which provide some safeguard for the mitigation of emerging contaminants below effect levels The monitoring effort can then focus on the integrity control of those barriers for classes of compounds

5.4.5.2 Finding Key Parameters for the Aggregate Evaluation of

the Water Quality

The definition of easy-to-monitor and ‘fit-for-all-purposes’ parameters is certainly highly desirable from an operator’s point of view Nevertheless the different con-straints given by regulations and case-by-case permits cannot be overcome with respect to the demanded water quality parameters and sampling frequencies Water quality control might be appropriate on shorter intervals to improve process reliabil-ity, end-user satisfaction and simply to avoid technical problems in the longer run

A presupposition for a key parameter and the respective way to monitor it (mea-surement point in the process, frequency, sample processing, reporting, feedback possibilities) is that the parameter should be suitable as an early warning indicator which shows that the process performance is about to fluctuate either on the basis of input variations or technical malfunctions Hence, it is required to set up a system of control points which are able to observe input, functionality of the treatment process

as well as product quality

5.4.5.3 The Timescale of the Measurement

While analyses are becoming more complex, market pressures are also dictating that the results are available more quickly

There are a number of new emerging instruments and techniques, such as particle counters and gene probe technologies, which hold considerable promise as monitor-ing tools It is expected that these technologies may provide reliable and inexpensive

Case Examples 343

methods to conduct parameter testing Future research and lower instrument costs will be required before such technologies become widely available

Promising results are also coming from the latest development of early warning systems for microbiological contamination Two examples are the development of

protocols for the examination of E coli that allow results to be obtained in the range

of measurement 10–50 CFU (colony forming units)/100 ml within 1 h (Morikawa

et al., 2006) and in the range 50–400 CFU/100 ml within 10 h (Braathen et al., 2005)

5.4.6 CASE EXAMPLES

The next section will provide three examples representing applications requiring different extents of monitoring in the context of water reuse:

rlimited (industrial cooling): class 7 (out of 7) of Figure 5.4.1;

rmoderately extensive (unrestricted irrigation): class 3 of Figure 5.4.1;

rfull-fledged (aquifer recharge for indirect drinking water supply): class 1 of Figure 5.4.1

5.4.6.1 Monitoring Strategy to Deliver Cooling Water Make-up

in Tienen, Belgium

The Tienen (Belgium) water reuse scheme reclaims 2 000 000 m3per year in order

to reduce the extraction of natural groundwater for close-circuit cooling water

make-up at a nearby chemical company The requirements for this application are stable quality and quantity, low turbidity, conductivity, suspended solids and temperature The wastewater treatment plant (WWTP) consists of a low loaded activated sludge system (oxidation ditch) with enhanced biological phosphorus removal and com-plies with the European Urban Wastewater Treatment Directive for Sensitive Areas (91/271/EC) (European Union, 1991) To prevent microbiological growth in the ducts, the effluent is disinfected with ozone, to obtain an ozone concentration of 3–4 mg/l at the entry of the cooling water make-up storage facility Since the

start-up of the use of reclaimed water in 2003, no problems have occurred regarding regrowth in the cooling circuit, with the reclaimed water having a total cell count of 100–200 CFU/ml

To detect and retain reclaimed water of unacceptable quality, conductivity and turbidity are measured on-line Should the conductivity exceed 1700μS/cm or the

turbidity be higher than 3 NTU (nephelometric turbidity units), the reclaimed water would be diverted to the surface water body and the system be provided with an alternative water supply (groundwater) Temperature is also measured continuously Seasonal evolution of temperature implies that the reclaimed water cannot be used

during summer months (Thoeye et al., 2006).

5.4.6.2 Monitoring Strategy for Agricultural Irrigation

in the Dan Region, Israel

The Dan Region Reclamation Project treats around 140 million m3 per year (or

340 000 m3/day) from the Greater Tel-Aviv The effluent of the conventional acti-vated sludge plant (WWTP) is conveyed to a tertiary treatment composed of a soil aquifer treatment (SAT), from where it is recovered and distributed throughout a 100

km pipeline and seasonal reservoirs The project should ensure the distribution of effluents suitable for unrestricted irrigation quality, i.e enabling the irrigation of all kinds of crops

The monitoring programme includes analyses of physical, chemical and bio-logical parameters, at various sampling points (Figure 5.4.4) and time intervals (Table 5.4.6)

Besides sampling in different points, there is 24 h monitoring of the WWTP and SAT operation in a manned control room in the WWTP and also visual inspections are performed along the distribution line up to the end-user

N

1 Influent to WWTP

3 Ashdod junction:

2 WWTP effluent

Reclaimed water after SAT

4 Granot-reservoir

5 Lake Zohar-reservoir

4 Noga-reservoir

4 Zohar B-reservoir

4 Tkuma-reservoir

6 Urim junction − Third line

4 Lev Hanegev-reservoir

5 Habsor reservoirs-north and south

5 Nir- Am

reservoir

4

Magen-reservoir

6 Kerem shalom

junction-Third line

Blue − Operational reservoirs Red − Seasonal reservoirs

Figure 5.4.4 Scheme of Dan Region project with the critical control points for monitoring

(Cikurel and Aharoni, 2004)

Case Examples 345

Table 5.4.6 Monitoring practice at the Dan Region reclamation scheme

Distribution system: chlorine Pumping stations: sand detectors Infiltration fields (each basin): flow, water level and condition of the valve (opened/closed)

and alkalinity (2) Hardness , Ca, detergents , fats and oils, DO (1)

Ba, Zn, Cn , Se, Pb, Cu, Hg, Mo, Ni, Co, F,

Sr, Li, Al, Sn, Be, Va, Phenol, oil and

grease, Total bacteria, E coli, faecal coliforms, faecal streptococcus, colour

Intermediate reservoirs (monthly/twice a

month in the hot season)

Bacteriology, Ervinia, chlorophyll, alga, TSS, VSS, UV, DO, pH, temperature, turbidity

DO, dissolved oxygen; TSS, total suspended solids; vss, volatile suspended solids.

Along the distribution line there is different equipment to monitor the clogging capacity in the line At the exit of the seasonal reservoirs along the distribution system there are wire filters (80–120 mesh) to prevent algae and other clogging matter from the reservoirs to reach the pipe-lines The degree of clogging (mainly by algae) is also measured by means of a by-pass system which also consists of a wire filter The degree of clogging is indicated by the number of backwashes performed

in a given time interval

The monitoring practice implies:

1 The measurement of the infiltration velocity is conducted in an automatic way

2 Daily automatic measurement and recording of the water level in the basin, inte-grated with daily inspection performed on-site by an operator

3 Optimized cleaning routine, based on the infiltration velocity and assisted by the decision of the field operator

4 A preventive cleaning programme, applied every 15–30 days, depending on the clogging rate

5 Ploughing (by using disc or plough), chosen according to the field situation Sand removal is seldom practiced

5.4.6.3 Monitoring Strategy to Close the Water Cycle at the

Flemish Coast, Belgium

At the Belgian coast, the Intermunicipal Water Company of the Veurne region (IWVA) is responsible for the potable water production and supply in the area; the source for the potable water production was the sandy aquifer in the dunes near the coast Tourist activities in the area resulted in a largely varying water demand and saline intrusion, which was threatening the sustainability of the potable water production In 2002 the IWVA started artificial recharge of an unconfined aquifer

in its dune water catchment St Andr´e Wastewater effluent was used as the source for the production of infiltration water This plant, with a production capacity of

2 500 000 m3/year, combined membrane filtration techniques to achieve the strin-gent standards set for the quality of the infiltration water The whole project was developed to create a sustainable groundwater management; the natural groundwa-ter extraction was reduced from 3 700 000 m3/year to 2 700 000 m3/year By 2010 another 500 000 m3/year will be saved (Van Houtte and Verbauwhede, 2005) Saline intrusion was gradually prevented and the sustainability of the water production was increased The treatment scheme is presented in Figure 5.4.5

The regulatory water quality requirements for the water reclamation scheme be-fore infiltration are: temperature, pH, conductivity, chloride, sulfate, magnesium, sodium, total hardness, nitrate, nitrite, ammonia, aluminium, iron, manganese, cop-per, zinc, phosphorous, fluoride, cyanide, chrome, mercury, nickel, lead, antimony, selenium and trihalomethanes

The operational monitoring practice to prevent the infiltration of substandard water is summarized in Table 5.4.7

wastewater

effluent

prescreen

1560 m3

UF

RO

70 m 3

UV

concentrate

to canal

Cartridge filter

ZeeWeed® 14.040 m2

7.380 m2

7.380 m2

8" BW 30 LE - 440 DOW

to the dunes

20

20 10

10 WWTP

Figure 5.4.5 Tertiary treatment scheme of St Andr´e aquifer recharge project in Wulpen (IWVA)