Thorkild Hvitved-Jacobsen

Measurement of Pools of Protein: Carbohydrate and Lipid in Domestic Wastewater

A more detailed characterization of organic matter in domestic wastewater than given by the bulk parameters BOD, COD and TOC is needed to increase the knowledge about transformations in sewer systems and the quality of wastewater as input to the wastewater treatment processes. In this paper results of various selected methods optimized for analysing pools of carbohydrate, protein and lipid in domestic wastewater were described and discussed. The most suitable method for measurement of protein was the method of Lowry et al. (1951), for carbohydrate it was the anthrone method originally introduced by Dreywood (1946) and for lipid it was an infrared method modified from Standard Methods (APHA et al., 1985). The modified methods showed high precision and compounds in the wastewater did not seem to interfere. The results of the methods were, however, slightly influenced by the choice of standard. A case study was performed using the methods for characterization of wastewater from catchment areas of different characteristics. The fractions of total protein, carbohydrate and lipid of total COD were, on average, 28, 18 and 31% with standard deviations of 4, 6 and 10%, respectively. The dissolved carbohydrate fraction varied considerably—10% as an average of dissolved COD, and 7% as standard deviation, presumably due to degradation in the sewers influenced by differences in residence times.

Corrosion of concrete sewers—The kinetics of hydrogen sulfide oxidation

Hydrogen sulfide absorption and oxidation by corroding concrete surfaces was quantified in a test rig consisting of 6 concrete pipes operated under sewer conditions. The test rig was placed in an underground sewer monitoring station with access to fresh wastewater. Hydrogen sulfide gas was injected into the pipe every 2nd hour to peak concentrations around 1000 ppm. After some months of operation, the hydrogen sulfide became rapidly oxidized by the corroding concrete surfaces. At hydrogen sulfide concentrations of 1000 ppm, oxidation rates as high as 1 mg S m(-2) s(-1) were observed. The oxidation process followed simple nth order kinetics with a process order of 0.45-0.75. Extrapolating the results to gravity sewer systems showed that hydrogen sulfide oxidation by corroding concrete is a fast process compared to the release of hydrogen sulfide from the bulk water, resulting in low gas concentrations compared with equilibrium. Balancing hydrogen sulfide release with hydrogen sulfide oxidation at steady state conditions demonstrated that significant corrosion rates--several millimeters of concrete per year--can potentially occur at hydrogen sulfide gas phase concentrations well below 5-10 ppm. The results obtained in the study advances the knowledge on prediction of sewer concrete corrosion and the extent of odor problems.

Highway Runoff and Potential for Removal of Heavy Metals in an Infiltration Pond in Portugal

Highway runoff from IP 4, a mountain road in the north-east of Portugal, has been monitored using a system integrating a raingauge, a flowmeter and an automatic water sampler. Average daily traffic (ADT) is 6000 and the study catchment has 5970 m2 of total area and 2500 m2 of road pavement. A single stormwater outlet discharges into an infiltration pond with overflow to a creek. Sampling was carried out before the runoff water entered the pond. Among the parameters analysed in the runoff water, the heavy metals cadmium (Cd), chromium (Cr), copper (Cu), lead (Pb) and zinc (Zn) were emphasised because of their toxicity. Concentrations of Cd and Cr were usually lower than the detection limit (1 microgram/l). Copper levels found were between 1 and 54 micrograms/l; lead from 1 to 200 micrograms/l and zinc from 50 to 1460 micrograms/l. A first flush effect was observed, meaning that the first 50% of the runoff volume for each event typically transported between 61 and 69% of the total suspended solids, Zn, Cu and Pb loads. Runoff water is totally infiltrated into the pond and heavy metals are being sorbed to the soil. Soils used in infiltration ponds should have specific characteristics in order to perform effectively and ensure groundwater protection. Not only well-known soil texture and composition characteristics are relevant: the soil sorption capacity--the extension and reversibility of the processes--is of main importance in this kind of highway runoff treatment. Experiments concerning the sorption of Zn, Cu and Pb to soils, followed by desorption at pH values of 2, 4 and 6 were conducted in the laboratory. These experiments were performed with the soil existing at the highway IP 4 infiltration pond and with two other common types of Portuguese soils. The three types of soil showed different behaviours, which must be related to their characteristics; the soil pH seemed to play a significant role in controlling the Zn, Cu and Pb sorption processes. As expected, as lowering of the pH value increased the desorption rate. The infiltration pond soil is the one with the lowest sorption capacity, however, it showed a relatively high sorption strength which means that it is considered reliable, concerning highway runoff treatment and groundwater protection.

Solids in Sewers: characteristics, effects and control of sewer solids and associated pollutants

This Report presents information on the current state of knowledge of the origins, occurrence, nature and effects of sewer solids for use by engineers, scientists, administrators and water quality planners for the planning, design and operation of sewerage systems. The report addresses both sewer maintenance requirements and environmental protection issues. Increasing environmental standards, coupled with public expectations, have led to stringent water quality standards. In response to this, it has been necessary to develop new methodologies and computer based analytical techniques to model and understand the performance of all aspects of waste water systems. Fundamental to these techniques is the understanding of the way in which sewer solids contribute to the poor performance of wastewater systems and consequential environmental damage. The information presented in this Report about the origins, nature, movement, hydraulic and polluting effects of solids in sewers has enabled strategies and rules to be developed for the management of sewerage systems to minimise the deleterious effects of these solids and associated pollutants. This title belongs to Scientific and Technical Report Series ISBN: 9781900222914 (Print) ISBN: 9781780402727 (eBook)

Urban Drainage Impacts on Receiving Waters

The paper deals with the causes and consequences of urban storm drainage impacts on receiving waters and discusses available methods and tools for implementation of structural as well as non-struct...

Treatment Systems for Urban and Highway Run-off in Denmark

To observe the required quality in Danish receiving water systems, pollution from urban and highway run-off is of importance in many cases. There is therefore a potential demand for treatment of the wet-weather flow. An evaluation of relevant treatment methods was carried out for the National Agency for Environmental Protection. The wet detention pond was considered the most efficient and suitable solution for removal of the most important pollutants, i.e. phosphorus and heavy metals, in the storm-water run-off from urban catchments and highways. Recommended design procedures are described and exemplified in this paper.

Influence of pipe material and surfaces on sulfide related odor and corrosion in sewers

Hydrogen sulfide oxidation on sewer pipe surfaces was investigated in a pilot scale experimental setup. The experiments were aimed at replicating conditions in a gravity sewer located immediately downstream of a force main where sulfide related concrete corrosion and odor is often observed. During the experiments, hydrogen sulfide gas was injected intermittently into the headspace of partially filled concrete and plastic (PVC and HDPE) sewer pipes in concentrations of approximately 1,000 ppm(v). Between each injection, the hydrogen sulfide concentration was monitored while it decreased because of adsorption and subsequent oxidation on the pipe surfaces. The experiments showed that the rate of hydrogen sulfide oxidation was approximately two orders of magnitude faster on the concrete pipe surfaces than on the plastic pipe surfaces. Removal of the layer of reaction (corrosion) products from the concrete pipes was found to reduce the rate of hydrogen sulfide oxidation significantly. However, the rate of sulfide oxidation was restored to its background level within 10-20 days. A similar treatment had no observable effect on hydrogen sulfide removal in the plastic pipe reactors. The experimental results were used to model hydrogen sulfide oxidation under field conditions. This showed that the gas-phase hydrogen sulfide concentration in concrete sewers would typically amount to a few percent of the equilibrium concentration calculated from Henrys law. In the plastic pipe sewers, significantly higher concentrations were predicted because of the slower adsorption and oxidation kinetics on such surfaces.

Removal of contaminants in highway runoff flowing through swales

Abstract Simulated highway runoff was pumped over a well established grassy swale at Maitland Interchange and a newly constructed swale at EPCOT Interchange, near Orlando, Florida to investigate mass transport and removal efficiencies for nutrients and heavy metal concentrations under controlled environments. Dissolved metal concentrations, particularly those existing in ionic species, were better removed than phosphorus and nitrogen. Nutrient concentrations in highway runoff flowing over roadside swales may increase. However percent mass removal of all pollutants were found to be higher than concentration removal due to infiltration.

The impact of combined sewer overflows on the dissolved oxygen concentration of a river

Abstract As described in the preceding paper by Harremoes (Harremoes, Water Res.16, 1093–1098, 1982) it is important to distinguish between removal and degradation of organic matter for non-steady-state discharges to rivers. These effects were investigated to determine the impact of combined sewer overflows on the dissolved oxygen concentration of a small river. Two different effects on the DO-concentration in the receiving river were observed during and after the passage of the bulk of combined sewage discharged at an existing outlet: 1. 1. An immediate effect caused mainly by degradation of the soluble BOD-fraction in the water body and by direct absorption and degradation of organic matter at the bottom. 2. 2. A delayed effect caused by degradation of adsorbed soluble, colloidal and fine particulate organic matter. After the passage of the bulk discharge a delayed effect on the DO-concentration in the river would be observed. This delayed effect lasted 12–24 hours after the discharge event. Only 4% of the discharged organic matter was degraded during passage of the investigated stretch of the river, approx. 4 km. On the other hand about 35% of the discharged organic matter was removed by transfer to the bottom sediments. The rest was carried past the stretch of river investigated. This results in a rate of adsorption from the water phase of k = 9 m day−1. The deposited organic matter was degraded with a first order reaction rate of K4 = 0.75 day−1.

Heavy metal accumulation and transport through detention ponds receiving highway runoff

Sediment accumulations and associated heavy metal concentrations into retention/detention ponds receiving highway runoff from several ponds and metal concentrations in various sediment layers were analyzed to determine the extent of vertical migration. Extraction of heavy metals had been evaluated using various solutions including the United States Environmental Protection Agency Toxicity Characteristics Leaching Procedures (TCLP). Also, sediments were incubated under various conditions of redox potential and pH to investigate the effects of changes in sediment conditions on the stability of metal-sediment associations.