By Stanley Wallulis - Professional Engineer

 

 

Reliability of Operation of Water Treatment Plants.

Historically there has been numerous failures of water treatment plants to be operated in compliance with the Safe Drinking Water Act Amendments of 1966. The following information for 1996, the most recent year of record, is derived from the December 1998 issue of WATER/Engineering & Management:

18,410 violations were for not meeting the Minimum Contaminant Level (MCL) and treatment technique requirements.

123,207 violations mostly for not meeting monitoring and reporting requirements.

How soon we forget that water that had been treated by a modern water treatment plant in Milwaukee, Wisconsin in 1993 permitted a Cryptosporidium outbreak resulting in making 400,000 people sick, 4,000 hospitalized, and caused more than 50 deaths.

In the operation of a water treatment plant treating highly polluted waters, there is a considerable time lag for several tests between the time some samples are collected and by the time they are analyzed. Consequently the water is already in the distribution system and delivered to customers before the results are known.

Also if the operators of a water treatment made an operational error, do you think they are likely to own up to it, and face the loss of their present job and place at risk their future employability?

The proponents of utilizing the Willamette River as a water source have stated that the proposed treatment process will remove all harmful contaminants and/or at least down to the current state and federal standards, with some "waffling" back on forth in response to questions.

Testing is needed to document that all the known and unknown contaminants (yet to be identified) will not be permitted to pass through harmful contaminants and endocrine disrupters into the treated water. As our technology and currently approved studies continues to advance our knowledge, several more harmful contaminants and complex synergistic combinations of harmful contaminants will be identified.

The quotation below is but one illustration of the inability of the proposed water treatment process of the Willamette to remove all harmful contaminants.

"A Penn State environmental engineer* has developed the first successful microbiological process for treating drinking water contaminated by perchlorate, …..

‘Recent improvements in the detection of perchlorate have shown that it has become a widespread contaminant of water in the western United States.’ Logan said. ‘The California Department of Health Services found 30 percent of 232 wells sampled were contaminated. The Southern Nevada Water Authority found perchlorate in its tap water in just under action level.’

 High doses of perchlorate interfere with the absorption of iodine by the thyroid and is a serious human health concern when present in drinking water. However, until Logan demonstrated his process, there was no proven removal technique available for the relatively low concentrations found in the water supply." *Dr. Bruce E. Logan.

 

The following excerpt is from this same publication:

"Citizens Know Little of Drinking Water Safety.

The amount of knowledge that representative citizens demonstrated on drinking water safety in recent discussions ranged from ‘little to none’ the EPA reports.….."^a1

 

The following has been excepted from page 16 of the November, 1998 issue of American Water Works Association Journal.

"USEPA has accepted final recommendations from the Endocrine Screening and Testing Advisory Committee for establishing a first-ever screening and testing program as required by the 1996 Food Quality Protection Act and Safe Drinking Water Act (SWDA) amendments. USEPA’s program proposal, due by year’s end, will focus on running about 15,000 suspect chemicals through prescreening assays that will identify those needing further analysis."

There are no plans by the City to have their consultants test for the 15,000 chemicals that may be present in the Willamette River.

There has been several published instances of fines being levied for pollutants being discharged into the Willamette River by public and private entities over the recent years. In addition on a broader basis the following:

"WASHINGTON, D.C. – In two separate actions, Fairfield, Conn. - based General Electric Co. (GE) and Russell, Ky. - based Ashland Inc. agreed to pay $200 million and $32.5 million, respectively, to settle allegations related to significant environmental contamination, said EPA and the U.S. Department of Justice.

…..GE will remove contaminants sediments from the area of the Housatonic River closest to the plant, said EPA, and will fund much of the cost of an additional Agency-conducted cleanup. In addition the company agreed to pay $15 million in damages for alleged river-damaging hazardous substance releases.

Ashland agreed to pay more than $5.8 million in civil penalties to settle allegations of illegal pollutant discharges and reporting violations at three company-owned petroleum refineries in Kentucky, Minnesota and Ohio, said EPA. The company also will spend $12 million to correct the violations and another $14.9 million to conduct supplemental environmental projects in these areas." ^a2

 

The following comments are by Janet Reno, U.S. Attorney, and Carol Browner, U.S. Environmental Protection (EPA) Administrator:

"Reno and Browner announced Shell Oil Co. agreed to pay $500,000 to improve water quality and protect wildlife in the Mississippi River Basin. The payment comes as part of an agreement to resolve allegations that the company violated environmental regulations."

"Chuck Grace, U.S. attorney for the Southern District of Illinois, said he and other U.S. attorneys have concluded that there are times when criminal action is the only action effective against polluters.

‘Large companies often build in huge fines as a cost of doing business, and the incentive for change is minimal,’ Grace said. ‘But when you look at whether corporate officers as individuals have been engaged in criminal activity …then you begin to catch people’s attention. The prospect of paying a huge fine by the corporation, and somebody going to jail, is certainly a wake-up-call.^a3

 

Reliability & Liability Possible with Willamette River as a Source.

From the December 1998 issue of the AWWA Mainstream Publication.

"The attorney defending Milwaukee against claims stemming from the city’s 1993 Cryptosporidium outbreak discussed emerging liability risks water suppliers may be facing and how to manage them.

Linda Hansen said the Milwaukee cases raises many unanswered questions about how product liability law may apply to tap water, noting that strict liability only requires the plantiff to show that the problem was connected to the product and that regulatory compliance is not a protection (although non-compliance spells certain defeat).

 

5. Operating Experiences at VOC Treatment Facilities (w/GAC).

From the January 1999 issue of the AWWA Optflow Publication.

"…GAC adsorption have demonstrated on a full-scale basis excellent performance in achieving high VOC-removal efficiencies. …..

….The presence of other synthetic or natural organics can also reduce the effectiveness of GAC in removing specific VOC’s.

 

The removal of VOC’s using adsorption typically is 100 percent effective when the activated carbon is initially placed in service. Over time and depending on the particular VOC or mix of VOC’s being removed, specific organics will break through the activated carbon and appear in the treated water.

While the GAC appeared to be effective for controlling more volatile compounds such as TCE and tetrachloroethene raw waters for most of the systems included one or more relatively less volatile compounds, such as methanes, propanes, and gasoline components such as MTBE.

Influent SOC concentrations were relatively low compared to those for the packed -column systems. Seven systems reported individual effluent SOC concentrations of less than 10 m g/L.

 

Operating Problems

high-rate backwashing caused movement of the GAC retaining screen, permitting a release of GAC to the distribution system.

occasional consumer complaints of black particles in the water. This problem was addressed by reviewing and improving backwash procedure."

 

From the January 1999 issue of Water Engineering and Management, page 22.

"The Rule also allows plants to find the point of diminishing return for TOC reduction, so enhanced coagulation operates most efficiently. This involves a lab study that identifies when an additional PPM of coagulant fails to remove 0.3 PPM of TOC. The study must account for pH depression and coagulant dosage. The Rule also defines the lowest pH at which a plant must look for the point of diminishing return (Table 3).

Visual and colorimetric tests can help set coagulant dosage if TOC shows up as color. Unfortunately, TOC can change without a noticeable effect on color, turbidity, pH or other raw water values. It includes many types of compounds having different charge demands, molecular weights,, hydrophilic/hydrophobic natures and other qualities that affect treatment, this means that raw water quality can shift as mixtures of problematic compounds change over time, even if the total TOC is almost steady.

…Lab tests for TOC, while the most direct, are too involved for operators to do while running a plant. In addition, outside labs are often of little help in making immediate treatment decisions because TOC results can take days to return.

The high coagulant levels used in enhanced coagulation raise realistic concerns about increases in turbidity. In this regard, the data showed that when the coagulant dose was raised to minimize DOC or SUVA, filtered water turbidity generally increased noticeably.

…..A switch to enhanced coagulation, if not done well, can raise costs and undermine goals involving such areas as sludge reduction, pH control, corrosion control, and finished water turbidity and metal residuals."

 

 

Filtration through GAC and Sand Filters.

The following is from the January issue of Water Engineering & Management, page, 16.

"This study revealed that chloramination in post GAC-filtered, chlorine depleted effluent water proceeds without interference to chloramine formation. However, it seems to produce an unknown agent during GAC filtration that induces the slow dissipation of disinfectants (chloramine). Formed chloramine was found to be very unstable in GAC filtered water as compared with the stability of the same disinfectant formed in the basin and filtered through sand media. Slow dissipation of formed chloramine begins almost as soon as chloramine is formed in the GAC effluent in the clear well.

 

NITRIFICATION

The new GAC installation met all expectations during the early months with respect to the removal of trihalomethane (THM), total organic carbon (TOC) and monochloramine. However, nitrification had developed as one of the problems associated with GAC filtration (e.g. desorption, bacterial growth, competitive effect and backwash effort on GAC performance).

 

Disinfectants Decay Mechanism

…….It would be interesting to isolate and identify the agents(s) responsible for disinfectant dissipation. There are three possibilities:

GAC particles are derived from GAC filter media,

Bacteria or algae attached to GAC particles, or

Metabolic product was released from bacteria in the biofilmed GAC and its interaction with disinfectant(s) caused the formation of GAC particles.

The GAC has a catalytic capacity to convert chloramine into ammonia and nitrogen. J. Skadson (1993) suggested that an increase in sporadic standard plate count in distribution systems may result from a lowered chloramine level due to the entry of GAC, GAC fine inactivate chloramine 5 mg/L to 2.5 with the concentration as low as 2.8 mg/L (AWWRF, 1992).

 

8. Strategies for Minimizing Ozonation By-Products in Drinking Water.

The following is from page 30 of the February 1998 issue of Water Engineering and Management.

"…However, ozonation can also lead to the formation of potentially harmful by-products inclusive of bromate ions (BrO₃), aldehydes and peroxides.

…Treatment facilities that achieve a specified percent removal of TOC prior to the application of a continuous disinfectant or that achieve a residual TOC concentration <2 mg/l prior to the application of a continuous disinfectant are considered to be in compliance.

….Further, conflicting data suggest the possibility that formaldehyde is carcinogenic at concentrations produced in drinking water during ozonation. Additionally, aldehydes may be viewed as surrogates for a large number of polar organics that are formed at low levels when ozone is used in the treatment of natural water. Of major concern regarding such polar by-products is their high biodegradability. High levels of these compounds in distribution systems can promote microbial regrowth leading to operational problems and the possible exposure of consumers to gastrointenstinal disease. Compounds having the potential of forming include peroxides that have more serious health effects than aldehydes themselves.

 

Although the use of O₃ as an alternative disinfectant to chlorine will not produce chlorinated trihalomethanes (THMs), haloacetic acids (HAAs) or chlorinated by-products, it can react with NOM to produce a variety of oxidation by-products that typically include aldehydes, aldo- and keto-acids, carboxylic acids and peroxides, NOM, a major component of TOC, is a complex matrix of organic chemicals that can be derived from partial bacterial degradation of soil, living organisms and plant detritus. Such oxidation by-products may form by the following reaction:

O₃ + NOM à Oxidation By-Products

…..Coagulation can be an effective pretreatment technique subsequent to GAC or membrane filtration in that it removes particles that might clog GAC beds, reducing the frequency of carbon regeneration and replacement, and it removes NOM, notorious for shortening membrane lives.

Further confirmation that O₃ dose affects the formation of by-products is provided from findings that the formation of low molecular weight aldehydes and carboxylic acids increases initially with the O₃ dose.