Treatment of municipal wastewater UASB reactor effluent by unconventional flotation and UV disinfection.

Post-treatment of an UASB reactor effluent, fed with domestic sewage, was conducted using two-stage flotation and UV disinfection. Results were compared to those obtained in a parallel stabilisation pond. The first flotation stage employed 5 - 7.5 mg L(-1) cationic flocculant to separate off more than 99% of the suspended solids. Then, phosphate ions were completely recovered using carrier flotation with 5-25 mg L(-1) of Fe (FeCl3) at pH 6.3-7.0. This staged flotation led to high recoveries of water and allowed us to separate organic matter and phosphate bearing sludge. The water still contained about 1 x 10(2) NMP/100 mL total coliforms, which were removed using UV radiation to below detection levels. Final water turbidity was < 1.0 NTU, COD < 20 mg L(-1) O2 and 71 mNm(-1), the liquid/air interfacial tension. This flotation-UV flowsheet was found to be more efficient than the treatment in the stabilisation pond and appears to have some potential for water reuse. Results were discussed in terms of the biological, chemical and physicochemical mechanisms involved.     

Cooperative and noncooperative protection against transferable and filterable externalities

Given self-protection from an undesirable environmental externality, we examine, under several conditions, the efficiency properties of cooperative and noncooperative behavior. We demonstrate that if self-protection can transfer the externality to another agent, then noncooperative behavior will lead to overprotection. If self-protection filters or dilutes the externality, then noncooperation leads to underprotection. In addition, overprotection will worsen if an agent with more relative power is allowed a first-mover advantage or if the damage function is elastic and transferability is uncertain. Finally, a reduction in uncertainty about transferability will accentuate overprotection if the damage function is inelastic. Our results suggest that coordination of protection activities among agents will enhance the overall gains from environmental policy in the European Single Internal Market of 1992. Coordination minimizes the costs of environmental protection, thereby reducing the public credibility of its foes.     

Common Currencies vs. Monetary Independence

We study the optimal monetary policy in a two-country open-economy model under two monetary arrangements: (a) multiple currencies controlled by independent policy makers; (b) common currencies with a centralized policy maker.
Our findings suggest that: (i) monetary policy competition leads to higher long-term inflation and interest rates with large welfare losses; (ii) the inflation bias and the consequent losses are larger when countries are unable to commit to future policies; (iii) the welfare losses from higher long-term inflation dominates the welfare costs of losing the ability to react optimally to shocks.     

Trades and Quotes: A Bivariate Point Process

This article formulates a bivariate point process to jointlyanalyze trade and quote arrivals. In microstructure models,trades may reveal private information that is then incorporatedinto new price quotes. This article examines the speed of thisinformation flow and the circumstances that govern it. A jointlikelihood function for trade and quote arrivals is specifiedin a way that recognizes that an intervening trade sometimescensors the time between a trade and the subsequent quote. Modelsof trades and quotes are estimated for eight stocks using Tradeand Quote database (TAQ) data. The essential finding for thearrival of price quotes is that information flow variables,such as high trade arrival rates, large volume per trade, andwide bid–ask spreads, all predict more rapid price revisions.This means prices respond more quickly to trades when informationis flowing so that the price impacts of trades and ultimatelythe volatility of prices are high in such circumstances.     

Characteristics of particle-associated PAHs in a first flush of a highway runoff.

Runoff monitoring of six rainfall events was carried out in a highway, Winterthur, Switzerland focusing on first flush (runoff volume up to 2.88 mm). Six runoff events were used to investigate the characteristics of particle-associated PAHs in first flush. The fine fraction (< 45 microm) had a relatively higher contribution than the coarse fraction. A significant contribution of the coarse fraction was observed at some periods when the runoff flow rapidly increased. Fluctuation of PAH content during a runoff event was significant in the coarse fraction and, in contrast, the PAH content in the fine fraction was less fluctuating. The weighted average PAH content in each event ranged from 17 to 62 microg/g in total SS, from 23 to 54 microg/g in the fine fraction and from 16 to 84 microg/g in the coarse fraction. The loading of particle-associated PAHs from the first flush of highway runoff ranged from 0.06 to 0.22 g/ha in a total of 12 PAH species.